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# Method swap in Java – Algorithms for interview

Often in the process of solving a particular problem, two variables must exchange values. There are two options for implementing value exchange:

## Option 1: Swap Values ​​Using a Temporary Variable

We introduce a temporary variable that will temporarily hold the value from one variable:

``````int tmp = a;
a = b;
b = tmp;
``````

For example:

``````public class ChangeValues1 {
public static void main(String[] args) {
int a = 3;
int b = 5;

int tmp = a;
a = b;
b = tmp;

System.out.println("a = " + a);
System.out.println("b = " + b);
}
}
``````

## Option 2: Swap Values ​​without a Temporary Variable

The 3rd variable is not introduced, the exchange is achieved by addition and subtraction:

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``````a = a + b;
b = a - b;
a = a - b
``````

For example:

``````public class ChangeValues2 {
public static void main(String[] args) {
int a = 3;
int b = 5;

a = a + b; // a = 8, b = 5
b = a - b; // a = 8, b = 3
a = a - b; // a = 5, b = 3

System.out.println("a = " + a);
System.out.println("b = " + b);
}
}
``````
By Alex Kara on Apr 01, 2022