Java If Else
Java If-Else statement is used to execute on of the two code blocks based on a given condition.
In this tutorial, we will learn the syntax and examples for if else statement.
Syntax
The syntax of if else statement is
if(condition) { //if code block } else { //else code block }
If the condition
evaluates to true
, if code block is executed.
If the condition
evaluates to false
, else code block is executed.
Flow Diagram of if else statement
The following flow diagram depicts the execution flow of an if-else statement in Java.
Examples for if else statement in Java
1 Check if given number is positive using If Else statement in Java
In the following example, we are checking the condition that if x
is a positive number of not. We also have an else block accompanying if block. The condition in the if else statement would be x > 0
. The if block executes if the condition is true, or else, the else block executes.
Main.java
public class Main { public static void main(String[] args) { int x = -2; if(x > 0){ System.out.println("x is positive."); } else { System.out.println("x is not positive."); } } }
Output
x is not positive.
2 Check if given string contains World using If Else statement in Java
In the following example, we will check if given string contains “World” as substring, using if-else statement. If x is the given string, then the condition for if else statement is x.contains("World")
.
Main.java
public class Main { public static void main(String[] args) { String x = "Hello World"; if(x.contains("World")) { System.out.println("x contains \"World\"."); } else { System.out.println("x does not contain \"World\"."); } } }
Output
x contains "World".
Nested If-Else Statement
Since If-Else is just another statement in Java, we can write an If-Else statement inside another If-Else statement. Since an If-Else statement is nested in another If-Else, we may call this as Nested If-Else statement.
In the following example, we have written a Nested If-Else statement.
Main.java
public class Main { public static void main(String[] args) { int a = 3; if(a % 2 == 1) { System.out.println("a is odd number."); if(a<10) { System.out.println("a is less than 10."); } else { System.out.println("a is not less than 10."); } } else { System.out.println("a is even number."); } } }
Run the program and you will get the following output in console.
Output
a is odd number. a is less than 10.
Conclusion
In this Java Tutorial, we learned how to write an If-Else statement, nested if-else statement, and presented some Java examples.