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Java Scanner Class
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Java Expressions, Statements and Blocks

Java if...else Statement

In programming, we use the if..else statement to run a block of code among more than one alternatives.

For example, assigning grades (A, B, C) based on the percentage obtained by a student.

if the percentage is above 90 , assign grade A
if the percentage is above 75 , assign grade B
if the percentage is above 65 , assign grade C

1. Java if (if-then) Statement

The syntax of an if-then statement is:

Here, condition is a boolean expression such as age >= 18 .

if condition evaluates to true , statements are executed
if condition evaluates to false , statements are skipped

Working of if Statement

if the number is greater than 0, code inside if block is executed, otherwise code inside if block is skipped

Example 1: Java if Statement

In the program, number < 0 is false . Hence, the code inside the body of the if statement is skipped .

Note: If you want to learn more about about test conditions, visit Java Relational Operators and Java Logical Operators .

We can also use Java Strings as the test condition.

Example 2: Java if with String

In the above example, we are comparing two strings in the if block.

2. Java if...else (if-then-else) Statement

The if statement executes a certain section of code if the test expression is evaluated to true . However, if the test expression is evaluated to false , it does nothing.

In this case, we can use an optional else block. Statements inside the body of else block are executed if the test expression is evaluated to false . This is known as the if-...else statement in Java.

The syntax of the if...else statement is:

Here, the program will do one task (codes inside if block) if the condition is true and another task (codes inside else block) if the condition is false .

How the if...else statement works?

If the condition is true, the code inside the if block is executed, otherwise, code inside the else block is executed

Example 3: Java if...else Statement

In the above example, we have a variable named number . Here, the test expression number > 0 checks if number is greater than 0.

Since the value of the number is 10 , the test expression evaluates to true . Hence code inside the body of if is executed.

Now, change the value of the number to a negative integer. Let's say -5 .

If we run the program with the new value of number , the output will be:

Here, the value of number is -5 . So the test expression evaluates to false . Hence code inside the body of else is executed.

3. Java if...else...if Statement

In Java, we have an if...else...if ladder, that can be used to execute one block of code among multiple other blocks.

Here, if statements are executed from the top towards the bottom. When the test condition is true , codes inside the body of that if block is executed. And, program control jumps outside the if...else...if ladder.

If all test expressions are false , codes inside the body of else are executed.

How the if...else...if ladder works?

If the first test condition if true, code inside first if block is executed, if the second condition is true, block inside second if is executed, and if all conditions are false, the else block is executed

Example 4: Java if...else...if Statement

In the above example, we are checking whether number is positive, negative, or zero . Here, we have two condition expressions:

number > 0 - checks if number is greater than 0
number < 0 - checks if number is less than 0

Here, the value of number is 0 . So both the conditions evaluate to false . Hence the statement inside the body of else is executed.

Note : Java provides a special operator called ternary operator , which is a kind of shorthand notation of if...else...if statement. To learn about the ternary operator, visit Java Ternary Operator .

4. Java Nested if..else Statement

In Java, it is also possible to use if..else statements inside an if...else statement. It's called the nested if...else statement.

Here's a program to find the largest of 3 numbers using the nested if...else statement.

Example 5: Nested if...else Statement

In the above programs, we have assigned the value of variables ourselves to make this easier.

However, in real-world applications, these values may come from user input data, log files, form submission, etc.

Introduction
Java if (if-then) Statement
Example: Java if Statement
Java if...else (if-then-else) Statement
Example: Java if else Statement
Java if..else..if Statement
Example: Java if..else..if Statement
Java Nested if..else Statement

Sorry about that.

Assignment, Arithmetic, and Unary Operators

The simple assignment operator.

One of the most common operators that you'll encounter is the simple assignment operator " = ". You saw this operator in the Bicycle class; it assigns the value on its right to the operand on its left:

This operator can also be used on objects to assign object references , as discussed in Creating Objects .

The Arithmetic Operators

The Java programming language provides operators that perform addition, subtraction, multiplication, and division. There's a good chance you'll recognize them by their counterparts in basic mathematics. The only symbol that might look new to you is " % ", which divides one operand by another and returns the remainder as its result.

The following program, ArithmeticDemo , tests the arithmetic operators.

This program prints the following:

You can also combine the arithmetic operators with the simple assignment operator to create compound assignments . For example, x+=1; and x=x+1; both increment the value of x by 1.

The + operator can also be used for concatenating (joining) two strings together, as shown in the following ConcatDemo program:

By the end of this program, the variable thirdString contains "This is a concatenated string.", which gets printed to standard output.

The Unary Operators

The unary operators require only one operand; they perform various operations such as incrementing/decrementing a value by one, negating an expression, or inverting the value of a boolean.

The following program, UnaryDemo , tests the unary operators:

The increment/decrement operators can be applied before (prefix) or after (postfix) the operand. The code result++; and ++result; will both end in result being incremented by one. The only difference is that the prefix version ( ++result ) evaluates to the incremented value, whereas the postfix version ( result++ ) evaluates to the original value. If you are just performing a simple increment/decrement, it doesn't really matter which version you choose. But if you use this operator in part of a larger expression, the one that you choose may make a significant difference.

The following program, PrePostDemo , illustrates the prefix/postfix unary increment operator:

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Java Tutorial

Java methods, java classes, java file handling, java how to, java reference, java examples, java if ... else, java conditions and if statements.

You already know that Java supports the usual logical conditions from mathematics:

Less than: a < b
Less than or equal to: a <= b
Greater than: a > b
Greater than or equal to: a >= b
Equal to a == b
Not Equal to: a != b

You can use these conditions to perform different actions for different decisions.

Java has the following conditional statements:

Use if to specify a block of code to be executed, if a specified condition is true
Use else to specify a block of code to be executed, if the same condition is false
Use else if to specify a new condition to test, if the first condition is false
Use switch to specify many alternative blocks of code to be executed

The if Statement

Use the if statement to specify a block of Java code to be executed if a condition is true .

Note that if is in lowercase letters. Uppercase letters (If or IF) will generate an error.

In the example below, we test two values to find out if 20 is greater than 18. If the condition is true , print some text:

Try it Yourself »

We can also test variables:

Example explained

In the example above we use two variables, x and y , to test whether x is greater than y (using the > operator). As x is 20, and y is 18, and we know that 20 is greater than 18, we print to the screen that "x is greater than y".

The else Statement

Use the else statement to specify a block of code to be executed if the condition is false .

In the example above, time (20) is greater than 18, so the condition is false . Because of this, we move on to the else condition and print to the screen "Good evening". If the time was less than 18, the program would print "Good day".

The else if Statement

Use the else if statement to specify a new condition if the first condition is false .

In the example above, time (22) is greater than 10, so the first condition is false . The next condition, in the else if statement, is also false , so we move on to the else condition since condition1 and condition2 is both false - and print to the screen "Good evening".

However, if the time was 14, our program would print "Good day."

Test Yourself With Exercises

Print "Hello World" if x is greater than y .

Start the Exercise

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1.4. Expressions and Assignment Statements ¶

In this lesson, you will learn about assignment statements and expressions that contain math operators and variables.

1.4.1. Assignment Statements ¶

Remember that a variable holds a value that can change or vary. Assignment statements initialize or change the value stored in a variable using the assignment operator = . An assignment statement always has a single variable on the left hand side of the = sign. The value of the expression on the right hand side of the = sign (which can contain math operators and other variables) is copied into the memory location of the variable on the left hand side.

Figure 1: Assignment Statement (variable = expression) ¶

Instead of saying equals for the = operator in an assignment statement, say “gets” or “is assigned” to remember that the variable on the left hand side gets or is assigned the value on the right. In the figure above, score is assigned the value of 10 times points (which is another variable) plus 5.

The following video by Dr. Colleen Lewis shows how variables can change values in memory using assignment statements.

As we saw in the video, we can set one variable to a copy of the value of another variable like y = x;. This won’t change the value of the variable that you are copying from.

Click on the Show CodeLens button to step through the code and see how the values of the variables change.

The program is supposed to figure out the total money value given the number of dimes, quarters and nickels. There is an error in the calculation of the total. Fix the error to compute the correct amount.

Calculate and print the total pay given the weekly salary and the number of weeks worked. Use string concatenation with the totalPay variable to produce the output Total Pay = $3000 . Don’t hardcode the number 3000 in your print statement.

Assume you have a package with a given height 3 inches and width 5 inches. If the package is rotated 90 degrees, you should swap the values for the height and width. The code below makes an attempt to swap the values stored in two variables h and w, which represent height and width. Variable h should end up with w’s initial value of 5 and w should get h’s initial value of 3. Unfortunately this code has an error and does not work. Use the CodeLens to step through the code to understand why it fails to swap the values in h and w.

1-4-7: Explain in your own words why the ErrorSwap program code does not swap the values stored in h and w.

Swapping two variables requires a third variable. Before assigning h = w , you need to store the original value of h in the temporary variable. In the mixed up programs below, drag the blocks to the right to put them in the right order.

The following has the correct code that uses a third variable named “temp” to swap the values in h and w.

The code is mixed up and contains one extra block which is not needed in a correct solution. Drag the needed blocks from the left into the correct order on the right, then check your solution. You will be told if any of the blocks are in the wrong order or if you need to remove one or more blocks.

After three incorrect attempts you will be able to use the Help Me button to make the problem easier.

Fix the code below to perform a correct swap of h and w. You need to add a new variable named temp to use for the swap.

1.4.2. Incrementing the value of a variable ¶

If you use a variable to keep score you would probably increment it (add one to the current value) whenever score should go up. You can do this by setting the variable to the current value of the variable plus one (score = score + 1) as shown below. The formula looks a little crazy in math class, but it makes sense in coding because the variable on the left is set to the value of the arithmetic expression on the right. So, the score variable is set to the previous value of score + 1.

Click on the Show CodeLens button to step through the code and see how the score value changes.

1-4-11: What is the value of b after the following code executes?

It sets the value for the variable on the left to the value from evaluating the right side. What is 5 * 2?
Correct. 5 * 2 is 10.

1-4-12: What are the values of x, y, and z after the following code executes?

x = 0, y = 1, z = 2
These are the initial values in the variable, but the values are changed.
x = 1, y = 2, z = 3
x changes to y's initial value, y's value is doubled, and z is set to 3
x = 2, y = 2, z = 3
Remember that the equal sign doesn't mean that the two sides are equal. It sets the value for the variable on the left to the value from evaluating the right side.
x = 1, y = 0, z = 3

1.4.3. Operators ¶

Java uses the standard mathematical operators for addition ( + ), subtraction ( - ), multiplication ( * ), and division ( / ). Arithmetic expressions can be of type int or double. An arithmetic operation that uses two int values will evaluate to an int value. An arithmetic operation that uses at least one double value will evaluate to a double value. (You may have noticed that + was also used to put text together in the input program above – more on this when we talk about strings.)

Java uses the operator == to test if the value on the left is equal to the value on the right and != to test if two items are not equal. Don’t get one equal sign = confused with two equal signs == ! They mean different things in Java. One equal sign is used to assign a value to a variable. Two equal signs are used to test a variable to see if it is a certain value and that returns true or false as you’ll see below. Use == and != only with int values and not doubles because double values are an approximation and 3.3333 will not equal 3.3334 even though they are very close.

Run the code below to see all the operators in action. Do all of those operators do what you expected? What about 2 / 3 ? Isn’t surprising that it prints 0 ? See the note below.

When Java sees you doing integer division (or any operation with integers) it assumes you want an integer result so it throws away anything after the decimal point in the answer, essentially rounding down the answer to a whole number. If you need a double answer, you should make at least one of the values in the expression a double like 2.0.

With division, another thing to watch out for is dividing by 0. An attempt to divide an integer by zero will result in an ArithmeticException error message. Try it in one of the active code windows above.

Operators can be used to create compound expressions with more than one operator. You can either use a literal value which is a fixed value like 2, or variables in them. When compound expressions are evaluated, operator precedence rules are used, so that *, /, and % are done before + and -. However, anything in parentheses is done first. It doesn’t hurt to put in extra parentheses if you are unsure as to what will be done first.

In the example below, try to guess what it will print out and then run it to see if you are right. Remember to consider operator precedence .

1-4-15: Consider the following code segment. Be careful about integer division.

What is printed when the code segment is executed?

0.666666666666667
Don't forget that division and multiplication will be done first due to operator precedence.
Yes, this is equivalent to (5 + ((a/b)*c) - 1).
Don't forget that division and multiplication will be done first due to operator precedence, and that an int/int gives an int result where it is rounded down to the nearest int.

1-4-16: Consider the following code segment.

What is the value of the expression?

Dividing an integer by an integer results in an integer
Correct. Dividing an integer by an integer results in an integer
The value 5.5 will be rounded down to 5

1-4-17: Consider the following code segment.

Correct. Dividing a double by an integer results in a double
Dividing a double by an integer results in a double

1-4-18: Consider the following code segment.

Correct. Dividing an integer by an double results in a double
Dividing an integer by an double results in a double

1.4.4. The Modulo Operator ¶

The percent sign operator ( % ) is the mod (modulo) or remainder operator. The mod operator ( x % y ) returns the remainder after you divide x (first number) by y (second number) so 5 % 2 will return 1 since 2 goes into 5 two times with a remainder of 1. Remember long division when you had to specify how many times one number went into another evenly and the remainder? That remainder is what is returned by the modulo operator.

Figure 2: Long division showing the whole number result and the remainder ¶

In the example below, try to guess what it will print out and then run it to see if you are right.

The result of x % y when x is smaller than y is always x . The value y can’t go into x at all (goes in 0 times), since x is smaller than y , so the result is just x . So if you see 2 % 3 the result is 2 .

1-4-21: What is the result of 158 % 10?

This would be the result of 158 divided by 10. modulo gives you the remainder.
modulo gives you the remainder after the division.
When you divide 158 by 10 you get a remainder of 8.

1-4-22: What is the result of 3 % 8?

8 goes into 3 no times so the remainder is 3. The remainder of a smaller number divided by a larger number is always the smaller number!
This would be the remainder if the question was 8 % 3 but here we are asking for the reminder after we divide 3 by 8.
What is the remainder after you divide 3 by 8?

1.4.5. FlowCharting ¶

Assume you have 16 pieces of pizza and 5 people. If everyone gets the same number of slices, how many slices does each person get? Are there any leftover pieces?

In industry, a flowchart is used to describe a process through symbols and text. A flowchart usually does not show variable declarations, but it can show assignment statements (drawn as rectangle) and output statements (drawn as rhomboid).

The flowchart in figure 3 shows a process to compute the fair distribution of pizza slices among a number of people. The process relies on integer division to determine slices per person, and the mod operator to determine remaining slices.

Figure 3: Example Flow Chart ¶

A flowchart shows pseudo-code, which is like Java but not exactly the same. Syntactic details like semi-colons are omitted, and input and output is described in abstract terms.

Complete the program based on the process shown in the Figure 3 flowchart. Note the first line of code declares all 4 variables as type int. Add assignment statements and print statements to compute and print the slices per person and leftover slices. Use System.out.println for output.

1.4.6. Storing User Input in Variables ¶

Variables are a powerful abstraction in programming because the same algorithm can be used with different input values saved in variables.

Figure 4: Program input and output ¶

A Java program can ask the user to type in one or more values. The Java class Scanner is used to read from the keyboard input stream, which is referenced by System.in . Normally the keyboard input is typed into a console window, but since this is running in a browser you will type in a small textbox window displayed below the code. The code below shows an example of prompting the user to enter a name and then printing a greeting. The code String name = scan.nextLine() gets the string value you enter as program input and then stores the value in a variable.

Run the program a few times, typing in a different name. The code works for any name: behold, the power of variables!

Run this program to read in a name from the input stream. You can type a different name in the input window shown below the code.

Try stepping through the code with the CodeLens tool to see how the name variable is assigned to the value read by the scanner. You will have to click “Hide CodeLens” and then “Show in CodeLens” to enter a different name for input.

The Scanner class has several useful methods for reading user input. A token is a sequence of characters separated by white space.

Run this program to read in an integer from the input stream. You can type a different integer value in the input window shown below the code.

A rhomboid (slanted rectangle) is used in a flowchart to depict data flowing into and out of a program. The previous flowchart in Figure 3 used a rhomboid to indicate program output. A rhomboid is also used to denote reading a value from the input stream.

Figure 5: Flow Chart Reading User Input ¶

Figure 5 contains an updated version of the pizza calculator process. The first two steps have been altered to initialize the pizzaSlices and numPeople variables by reading two values from the input stream. In Java this will be done using a Scanner object and reading from System.in.

Complete the program based on the process shown in the Figure 5 flowchart. The program should scan two integer values to initialize pizzaSlices and numPeople. Run the program a few times to experiment with different values for input. What happens if you enter 0 for the number of people? The program will bomb due to division by zero! We will see how to prevent this in a later lesson.

The program below reads two integer values from the input stream and attempts to print the sum. Unfortunately there is a problem with the last line of code that prints the sum.

Run the program and look at the result. When the input is 5 and 7 , the output is Sum is 57 . Both of the + operators in the print statement are performing string concatenation. While the first + operator should perform string concatenation, the second + operator should perform addition. You can force the second + operator to perform addition by putting the arithmetic expression in parentheses ( num1 + num2 ) .

More information on using the Scanner class can be found here https://www.w3schools.com/java/java_user_input.asp

1.4.7. Programming Challenge : Dog Years ¶

In this programming challenge, you will calculate your age, and your pet’s age from your birthdates, and your pet’s age in dog years. In the code below, type in the current year, the year you were born, the year your dog or cat was born (if you don’t have one, make one up!) in the variables below. Then write formulas in assignment statements to calculate how old you are, how old your dog or cat is, and how old they are in dog years which is 7 times a human year. Finally, print it all out.

Calculate your age and your pet’s age from the birthdates, and then your pet’s age in dog years. If you want an extra challenge, try reading the values using a Scanner.

1.4.8. Summary ¶

Arithmetic expressions include expressions of type int and double.

The arithmetic operators consist of +, -, * , /, and % (modulo for the remainder in division).

An arithmetic operation that uses two int values will evaluate to an int value. With integer division, any decimal part in the result will be thrown away, essentially rounding down the answer to a whole number.

An arithmetic operation that uses at least one double value will evaluate to a double value.

Operators can be used to construct compound expressions.

During evaluation, operands are associated with operators according to operator precedence to determine how they are grouped. (*, /, % have precedence over + and -, unless parentheses are used to group those.)

An attempt to divide an integer by zero will result in an ArithmeticException to occur.

The assignment operator (=) allows a program to initialize or change the value stored in a variable. The value of the expression on the right is stored in the variable on the left.

During execution, expressions are evaluated to produce a single value.

The value of an expression has a type based on the evaluation of the expression.

clear sunny desert yellow sand with celestial snow bridge

1.7 Java | Assignment Statements & Expressions

An assignment statement designates a value for a variable. An assignment statement can be used as an expression in Java.

After a variable is declared, you can assign a value to it by using an assignment statement . In Java, the equal sign = is used as the assignment operator . The syntax for assignment statements is as follows:

An expression represents a computation involving values, variables, and operators that, when taking them together, evaluates to a value. For example, consider the following code:

You can use a variable in an expression. A variable can also be used on both sides of the = operator. For example:

In the above assignment statement, the result of x + 1 is assigned to the variable x . Let’s say that x is 1 before the statement is executed, and so becomes 2 after the statement execution.

To assign a value to a variable, you must place the variable name to the left of the assignment operator. Thus the following statement is wrong:

Note that the math equation x = 2 * x + 1 ≠ the Java expression x = 2 * x + 1

Java Assignment Statement vs Assignment Expression

Which is equivalent to:

And this statement

is equivalent to:

Note: The data type of a variable on the left must be compatible with the data type of a value on the right. For example, int x = 1.0 would be illegal, because the data type of x is int (integer) and does not accept the double value 1.0 without Type Casting .

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Overview of Java

Introduction to Java
The Complete History of Java Programming Language
C++ vs Java vs Python
How to Download and Install Java for 64 bit machine?
Setting up the environment in Java
How to Download and Install Eclipse on Windows?
JDK in Java
How JVM Works - JVM Architecture?
Differences between JDK, JRE and JVM
Just In Time Compiler
Difference between JIT and JVM in Java
Difference between Byte Code and Machine Code
How is Java platform independent?

Basics of Java

Java Basic Syntax
Java Hello World Program
Java Data Types
Primitive data type vs. Object data type in Java with Examples
Java Identifiers

Operators in Java

Java Variables
Scope of Variables In Java

Wrapper Classes in Java

Input/output in java.

How to Take Input From User in Java?
Scanner Class in Java
Java.io.BufferedReader Class in Java
Difference Between Scanner and BufferedReader Class in Java
Ways to read input from console in Java
System.out.println in Java
Difference between print() and println() in Java
Formatted Output in Java using printf()
Fast I/O in Java in Competitive Programming

Flow Control in Java

Decision making in java (if, if-else, switch, break, continue, jump).

Java if statement with Examples
Java if-else
Java if-else-if ladder with Examples
Loops in Java
For Loop in Java
Java while loop with Examples
Java do-while loop with Examples
For-each loop in Java
Continue Statement in Java
Break statement in Java
Usage of Break keyword in Java
return keyword in Java
Java Arithmetic Operators with Examples
Java Unary Operator with Examples
Java Assignment Operators with Examples
Java Relational Operators with Examples
Java Logical Operators with Examples
Java Ternary Operator with Examples
Bitwise Operators in Java
Strings in Java
String class in Java
Java.lang.String class in Java | Set 2
Why Java Strings are Immutable?
StringBuffer class in Java
StringBuilder Class in Java with Examples
String vs StringBuilder vs StringBuffer in Java
StringTokenizer Class in Java
StringTokenizer Methods in Java with Examples | Set 2
StringJoiner Class in Java
Arrays in Java
Arrays class in Java
Multidimensional Arrays in Java
Different Ways To Declare And Initialize 2-D Array in Java
Jagged Array in Java
Final Arrays in Java
Reflection Array Class in Java
util.Arrays vs reflect.Array in Java with Examples

OOPS in Java

Object Oriented Programming (OOPs) Concept in Java
Why Java is not a purely Object-Oriented Language?
Classes and Objects in Java
Naming Conventions in Java
Java Methods

Access Modifiers in Java

Java Constructors
Four Main Object Oriented Programming Concepts of Java

Inheritance in Java

Abstraction in java, encapsulation in java, polymorphism in java, interfaces in java.

'this' reference in Java
Inheritance and Constructors in Java
Java and Multiple Inheritance
Interfaces and Inheritance in Java
Association, Composition and Aggregation in Java
Comparison of Inheritance in C++ and Java
abstract keyword in java
Abstract Class in Java
Difference between Abstract Class and Interface in Java
Control Abstraction in Java with Examples
Difference Between Data Hiding and Abstraction in Java
Difference between Abstraction and Encapsulation in Java with Examples
Difference between Inheritance and Polymorphism
Dynamic Method Dispatch or Runtime Polymorphism in Java
Difference between Compile-time and Run-time Polymorphism in Java

Constructors in Java

Copy Constructor in Java
Constructor Overloading in Java
Constructor Chaining In Java with Examples
Private Constructors and Singleton Classes in Java

Methods in Java

Static methods vs Instance methods in Java
Abstract Method in Java with Examples
Overriding in Java
Method Overloading in Java
Difference Between Method Overloading and Method Overriding in Java
Differences between Interface and Class in Java
Functional Interfaces in Java
Nested Interface in Java
Marker interface in Java
Comparator Interface in Java with Examples
Need of Wrapper Classes in Java
Different Ways to Create the Instances of Wrapper Classes in Java
Character Class in Java
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Java Keywords
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Java Memory Management
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Garbage Collection in Java
Types of JVM Garbage Collectors in Java with implementation details
Memory leaks in Java
Java Virtual Machine (JVM) Stack Area

Classes of Java

Understanding Classes and Objects in Java
Singleton Method Design Pattern in Java
Object Class in Java
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Throwable Class in Java with Examples

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Packages In Java
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Java.util Package in Java
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Exceptions in Java
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Difference Between Atomic, Volatile and Synchronized in Java
Deadlock in Java Multithreading
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Difference Between Lock and Monitor in Java Concurrency
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Java.io.File Class in Java
Java Program to Create a New File
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Java.io.RandomAccessFile Class Method | Set 1
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Regex Tutorial - How to write Regular Expressions?
Matcher pattern() method in Java with Examples
Pattern pattern() method in Java with Examples
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java.lang.Character class methods | Set 1
Java IO : Input-output in Java with Examples
Java.io.Reader class in Java
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java.net.ServerSocket Class in Java
URL Class in Java with Examples

JDBC - Java Database Connectivity

Introduction to JDBC (Java Database Connectivity)
JDBC Drivers
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Types of Statements in JDBC
JDBC Tutorial
Java 8 Features - Complete Tutorial

Decision Making in programming is similar to decision-making in real life. In programming also face some situations where we want a certain block of code to be executed when some condition is fulfilled.

A programming language uses control statements to control the flow of execution of a program based on certain conditions. These are used to cause the flow of execution to advance and branch based on changes to the state of a program.

Java’s Selection statements:

switch-case
jump – break, continue, return

1. if: if statement is the most simple decision-making statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statements is executed otherwise not.

Syntax :

Here, the condition after evaluation will be either true or false. if statement accepts boolean values – if the value is true then it will execute the block of statements under it. If we do not provide the curly braces ‘{‘ and ‘}’ after if( condition ) then by default if statement will consider the immediate one statement to be inside its block. For example,

Time Complexity: O(1) Auxiliary Space : O(1)

2. if-else : The if statement alone tells us that if a condition is true it will execute a block of statements and if the condition is false it won’t. But what if we want to do something else if the condition is false? Here comes the else statement. We can use the else statement with the if statement to execute a block of code when the condition is false.

3. nested-if: A nested if is an if statement that is the target of another if or else. Nested if statements mean an if statement inside an if statement. Yes, java allows us to nest if statements within if statements. i.e, we can place an if statement inside another if statement.

Syntax:

Time Complexity: O(1) Auxiliary Space: O(1)

4. if-else-if ladder: Here, a user can decide among multiple options.The if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that ‘if’ is executed, and the rest of the ladder is bypassed. If none of the conditions is true, then the final else statement will be executed. There can be as many as ‘else if’ blocks associated with one ‘if’ block but only one ‘else’ block is allowed with one ‘if’ block.

5. switch-case: The switch statement is a multiway branch statement. It provides an easy way to dispatch execution to different parts of code based on the value of the expression.

Time Complexity : O(1)

Space Complexity : O(1)

The expression can be of type byte, short, int char, or an enumeration. Beginning with JDK7, the expression can also be of type String.
Duplicate case values are not allowed.
The default statement is optional.
The break statement is used inside the switch to terminate a statement sequence.
The break statements are necessary without the break keyword, statements in switch blocks fall through.
If the break keyword is omitted, execution will continue to the next case.

6. jump: Java supports three jump statements: break, continue and return . These three statements transfer control to another part of the program.

Terminate a sequence in a switch statement (discussed above).
To exit a loop.
Used as a “civilized” form of goto.
Continue: Sometimes it is useful to force an early iteration of a loop. That is, you might want to continue running the loop but stop processing the remainder of the code in its body for this particular iteration. This is, in effect, a goto just past the body of the loop, to the loop’s end. The continue statement performs such an action.

Return: The return statement is used to explicitly return from a method. That is, it causes program control to transfer back to the caller of the method.

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@rmalchow Correction, you don't necessarily have to initialize variable, it depends on what if statement does. If it returns out, for instance, then there is no need for initialization. - randomUser56789
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Note: The compound assignment operator in Java performs implicit type casting. Let's consider a scenario where x is an int variable with a value of 5. int x = 5; If you want to add the double value 4.5 to the integer variable x and print its value, there are two methods to achieve this: Method 1: x = x + 4.5. Method 2: x += 4.5.
Java if statement with Examples
Decision Making in Java helps to write decision-driven statements and execute a particular set of code based on certain conditions. The Java if statement is the most simple decision-making statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed otherwise not.
The if-then and if-then-else Statements (The Java™ Tutorials > Learning
The if-then Statement. The if-then statement is the most basic of all the control flow statements. It tells your program to execute a certain section of code only if a particular test evaluates to true.For example, the Bicycle class could allow the brakes to decrease the bicycle's speed only if the bicycle is already in motion. One possible implementation of the applyBrakes method could be as ...
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The if-else statement is the most basic of all control structures, and it's likely also the most common decision-making statement in programming. It allows us to execute a certain code section only if a specific condition is met. 2. Syntax of If-Else. The if statement always needs a boolean expression as its parameter.
Java if...else (With Examples)
Output. The number is positive. Statement outside if...else block. In the above example, we have a variable named number.Here, the test expression number > 0 checks if number is greater than 0.. Since the value of the number is 10, the test expression evaluates to true.Hence code inside the body of if is executed.. Now, change the value of the number to a negative integer.
Java if statements
Java if statements. The Java if statement enables your Java programs to make decisions about what code to execute depending on the state of variables, or values returned from methods. Here is a simple Java if example: System.out.println("it is valid"); System.out.println("it is not valid"); The if statement in this example tests the boolean ...
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You can also combine the arithmetic operators with the simple assignment operator to create compound assignments. For example, x+=1; and x=x+1; both increment the value of x by 1. The + operator can also be used for concatenating (joining) two strings together, as shown in the following ConcatDemo program:
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Java if-else. Decision-making in Java helps to write decision-driven statements and execute a particular set of code based on certain conditions. The if statement alone tells us that if a condition is true it will execute a block of statements and if the condition is false it won't. In this article, we will learn about Java if-else.
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15. You can use java ternary operator, this statement can be read as, If testCondition is true, assign the value of value1 to result; otherwise, assign the value of value2 to result. simple example would be, In above code, if the variable a is less than b, minVal is assigned the value of a; otherwise, minVal is assigned the value of b.
Assigning variables in if statements : r/javahelp
to make it more clear you can do: int x = 0; int y = 0; Example: int a; // This is a declaration. a = 0; // This is an initialization. int a = 1; // This is a declaration and initialization. which will avoid any compile time errors about x or y not being assigned like: variable x might not have been initialized.
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Java Conditions and If Statements. You already know that Java supports the usual logical conditions from mathematics: Less than: a < b Less than or equal to: a <= b Greater than: a > b Greater than or equal to: a >= b Equal to a == b; Not Equal to: a != b You can use these conditions to perform different actions for different decisions.
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The reason is: Performance improvement (sometimes) Less code (always) Take an example: There is a method someMethod() and in an if condition you want to check whether the return value of the method is null. If not, you are going to use the return value again. If(null != someMethod()){. String s = someMethod();
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An assignment statement designates a value for a variable. An assignment statement can be used as an expression in Java. After a variable is declared, you can assign a value to it by using an assignment statement. In Java, the equal sign = is used as the assignment operator. The syntax for assignment statements is as follows: variable ...
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Nested if in Java. Generally, if condition works like yes or no type. If the condition satisfies, it executes some block of code. Otherwise, it doesn't execute the code. Let us see the syntax of the simple if condition. Syntax : statements ; Nested means within. Nested if condition means if-within-if.
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The rule is not that "assignment can't be used in an if statement", but that "the condition in an if statement must be of type boolean". An assignment expression produces a value of the type being assigned, so Java only permits assignment in an if statement if you're assigning a boolean value.
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Java Conditional Statement Exercises [32 exercises with solution] [ An editor is available at the bottom of the page to write and execute the scripts. Go to the editor] 1. Write a Java program to get a number from the user and print whether it is positive or negative. Test Data Input number: 35 Expected Output : Number is positive Click me to ...
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This is the assigment. I believe I am only allowed to use If and else statements. The following algorith yields the season (Spring, Summer, Fall, or Winter) for a given month of the day. IF month is 1,2, or 3, season = "Winter. Else if month is 4, 5, or 6, season = "Spring". Else if month is 7,8, 9, season = "Summer".
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These are used to cause the flow of execution to advance and branch based on changes to the state of a program. Java's Selection statements: if. if-else. nested-if. if-else-if. switch-case. jump - break, continue, return. 1. if: if statement is the most simple decision-making statement.

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