Java Program to Check if two Arrays are Equal or not
In Java, comparing two arrays means checking if they have the same length and identical elements. This checking process ensures that both arrays are equivalent in terms of content and structure.
Example:
In Java, the simplest way to check if two arrays are equal in Java is by using the built-in Arrays.equals() method.
import java.util.Arrays;
public class GFG {
public static void main(String[] args) {
int a[] = {10, 20, 30};
int b[] = {10, 20, 30};
// Using Arrays.equals() to check
// if two arrays are equal
boolean r = Arrays.equals(a, b);
if (r) {
System.out.println("Equal");
} else {
System.out.println("Not Equal");
}
}
}
Output
Equal
Note: If there are repetitions, then counts of repeated elements should be the same for two arrays to be equal.
Other Methods to Check Arrays are Equal or Not
Using Arrays.deepEquals() method
In this example, we will use Arrays.deepEquals() to compare two nested arrays, including multi-dimensional elements. The method checks complete content along with structural equality of both arrays.
import java.util.Arrays;
public class ArraysDeepEquals {
// Function to check if nested arrays are equal
private static void check(Integer[][] a, Integer[][] b) {
// Using Arrays.deepEquals() to check if two nested arrays are equal
boolean res = Arrays.deepEquals(a, b);
// Printing the result directly
if (res) {
System.out.println("Equal");
} else {
System.out.println("Not Equal");
}
}
public static void main(String[] args) {
Integer[][] arr1 = { {10, 20, 30}, {40, 50} };
Integer[][] arr2 = { {10, 20, 30}, {40, 50} };
check(arr1, arr2);
Integer[][] arr3 = { {10, 20, 30}, {40, 50} };
Integer[][] arr4 = { {30, 25, 40}, {50, 61} };
check(arr3, arr4);
}
}
Output
Equal Not Equal
Explanation: First we initialize two nested arrays and insert elements in each array. Then Arrays.deepEquals() method is called to check if the nested arrays are equal with the result stored in a boolean variable res. At last, the result is printed and indicates whether the arrays are "Equal" or "Not Equal."
Without Using pre-defined Function
In this example, we check manually two arrays, if they are equal or not. We check it by comparing their lengths and individual elements. A loop iterates through each element of both arrays and if all elements match, the arrays are considered "Equal" otherwise, they are "Not Equal".
import java.util.Arrays;
public class ArrayEquals {
// Function to check if arrays are equal
private static void check(int a[], int b[]) {
// Initialize result to true
boolean res = true;
// Check if length of the two arrays are equal
if (a.length == b.length) {
// Loop through elements to compare them
for (int i = 0; i < a.length; i++) {
if (a[i] != b[i]) {
// Set false if any element differs
res = false;
break;
}
}
} else {
// Set false if lengths differ
res = false;
}
if (res) {
System.out.println("Equal");
} else {
System.out.println("Not Equal");
}
}
public static void main(String[] args) {
int a[] = { 10, 20, 30 };
int b[] = { 10, 20, 30 };
check(a, b);
int c[] = { 10, 20, 30 };
int d[] = { 45, 50, 55, 60, 65 };
check(c, d);
}
}
Output
Equal Not Equal
When to Use Which Method
- Using
Arrays.equals(): When we need to compare one-dimensional arrays, we should use this method as it checks if both arrays have the same elements in the same order. - Using
Arrays.deepEquals(): When we need to compare multi-dimensional or nested arrays, we can use this method as it checks structural and element equality across all nested levels. - Without Pre-defined Methods: When we need custom comparison logic or we want to avoid library methods, we can use a manual loop comparison.
