/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		 int[] arr = {1, 2, 3};
        int n = arr.length;
 
        List<List<Integer>> arrOutside = new ArrayList<>();
 
        for (int i = 0; i < n; i++) {
            for (int j = 0; j <=i ; j++) {
                List<Integer> arrInside = new ArrayList<>();
                for (int k = j; k<=i; k++) {
                    arrInside.add(arr[k]);
                }
                arrOutside.add(arrInside);
            }
        }
 
        System.out.println(arrOutside);
    }
 
}

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