# How to Get the Opposite of a Number in Java

## The challenge

Given a number, find its opposite.

Examples:

```.wp-block-code{border:0;padding:0}.wp-block-code>div{overflow:auto}.shcb-language{border:0;clip:rect(1px,1px,1px,1px);-webkit-clip-path:inset(50%);clip-path:inset(50%);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px;word-wrap:normal;word-break:normal}.hljs{box-sizing:border-box}.hljs.shcb-code-table{display:table;width:100%}.hljs.shcb-code-table>.shcb-loc{color:inherit;display:table-row;width:100%}.hljs.shcb-code-table .shcb-loc>span{display:table-cell}.wp-block-code code.hljs:not(.shcb-wrap-lines){white-space:pre}.wp-block-code code.hljs.shcb-wrap-lines{white-space:pre-wrap}.hljs.shcb-line-numbers{border-spacing:0;counter-reset:line}.hljs.shcb-line-numbers>.shcb-loc{counter-increment:line}.hljs.shcb-line-numbers .shcb-loc>span{padding-left:.75em}.hljs.shcb-line-numbers .shcb-loc::before{border-right:1px solid #ddd;content:counter(line);display:table-cell;padding:0 .75em;text-align:right;-webkit-user-select:none;-moz-user-select:none;-ms-user-select:none;user-select:none;white-space:nowrap;width:1%}```1: -1
14: -14
-34: 34``````

## The solution in Java

We return the number itself multiplied by a negative 1.

``````public class Solution {
public static int opposite(int number) {
return number *= -1;
}
}
```Code language: Java (java)```

This can be simplified further as:

``````public class Solution {
public static int opposite(int number) {
return -number;
}
}
```Code language: Java (java)```

There is also a built in method to help with this if you prefer, called `Math.negateExact()`:

``````public class Solution {
public static int opposite(int number) {
return Math.negateExact(number);
}
}
```Code language: Java (java)```

## Test cases to validate our solution

``````import org.junit.Test;
import static org.junit.Assert.assertEquals;

public class OppositeExampleTests {
@Test
public void tests() {
assertEquals(-1, Solution.opposite(1));
assertEquals(0, Solution.opposite(0));
assertEquals(25, Solution.opposite(-25));
}
}
```Code language: Java (java)```
Tags:
Subscribe
Notify of