Find the maximum products of any 2 numbers in the array

MaximumProduct.Java

package javaproblems;

public class MaximumProduct {
    public static void main(String[] args){
        int[] arr = {1,2,-3,4,5};
        getMaximumNumbers(arr);
    }
    
    public static void getMaximumNumbers(int[] arr){    
        int len = arr.length;
        
        if(len<2){
            System.out.println("Invalid Entry");
            return;
        }
        
        int firstNum = arr[0];
        int secondNum = arr[1];
        
        for(int i= 0; i<len; i++){
            for(int j=i+1; j<len; j++){
                if(arr[i]*arr[j]>firstNum*secondNum){
                    firstNum = arr[i];
                    secondNum = arr[j];
                }
            }
        }
        System.out.println("Maximum product number is "+firstNum*secondNum);
    }
}