The Difference Between the != and =! Operator in Java

1. Java != Operator Example
2. Java =! Operator Example

This tutorial introduces the difference between the != and =! operators with examples in Java.

The != operator is an equality operator that is used to check whether two operands are equal or not. The =! operator is a combination of two operators, one is an assignment, and the second is a negation operator that works on boolean value. And it is used to invert a boolean value.

There is no comparison between these as both are used for different purposes. Let’s start with some examples to understand the uses.

Java != Operator Example

The != operator, also known as not equal to, is an equality operator and is used to check the equality of two operands. It returns a boolean value that is either true or false. If the two operands are equal, then it returns false, true otherwise.

public class SimpleTesting{
	public static void main(String[] args){
		int a = 10,b = 10;
		System.out.println("a = "+a);
		System.out.println("b = "+b);
		boolean result = a!=b;
		System.out.println(result);
		a = 20;
		System.out.println("a = "+a);
		result = a!=b;
		System.out.println(result);
	}
}

Output:

a = 10
b = 10
false
a = 20
true

The expression (a != b) means ! (a == b): the opposite of a == b can also be written as !(a==b). See the example below.

public class SimpleTesting{
	public static void main(String[] args){
		int a = 10,b = 10;
		System.out.println("a = "+a);
		System.out.println("b = "+b);
		boolean result = !(a==b);
		System.out.println(result);
		a = 20;
		System.out.println("a = "+a);
		result = !(a==b);
		System.out.println(result);
	}
}

Output:

a = 10
b = 10
false
a = 20
true

Java =! Operator Example

The =! operator is used to assign the opposite boolean value to a variable. The expression a=!b is actually a= !b. It first inverts the b and then assigns it to a. See the example below.

public class SimpleTesting{
	public static void main(String[] args){
		boolean a = true, b = true;
		System.out.println("a = "+a);
		System.out.println("b = "+b);
		a= !b;
		System.out.println(a);
		b = false;
		System.out.println("b = "+b);
		a= !b;
		System.out.println(a);
	}
}

Output:

a = true
b = true
false
b = false
true

You can also use the =! operator with a conditional statement to make a code conditional, as we did in the below code. See the example below.

public class SimpleTesting{
	public static void main(String[] args){
		boolean a = true, b = true;
		System.out.println("a = "+a);
		System.out.println("b = "+b);
		if(a= !b) {
			System.out.println(a);  // does not execute
		}
		b = false;
		System.out.println("b = "+b);
		if(a= !b) {
			System.out.println(a);
		}
	}
}

Output:

a = true
b = true
b = false
true