CODEWITHSUNDEEP
javalistloopsmatrixarraylist
user3752566
user3752566

Reputation: 105

How to create dynamic matrix 2d in java?

I want to create dynamic matrix 2d using loop in java. My code is

class Mat {
   public static void main (String[] args) throws java.lang.Exception {
        List<List<Integer>> group = new ArrayList<>();
        List<Integer> single = new ArrayList<>();
        for (int i=0; i < 3; i++){
            for (int j=0; j < 3; j++){
            single.add(i);
            }
            group.add(single);
        }
        group.remove(3);
        System.out.println(group);
   }
}

First question, how to create dynamic matrix 2D with loop? I want an output like [[0,1,2], [0,1,2], [0,1,2]] and the matrix value saved in the variable group.

Second question, after being saved in the variable group, how about if I want to remove list (number 3) in the variable? So, output is [[0,1,2], [0,1,2]].

Thanks.

Upvotes: 0

Views: 266

Answers (1)

Naman
Naman

Reputation: 31868

For the rest of your code creates a list List<List<Integer>> by changing

single.add(i);

to 

single = new ArrayList<>(); // reset every iteration
for (int j=0; j < 3; j++) {
   single.add(j); // add 0,1,2
}

how if i want remove list (number 3) in the variable?

group.remove(2); //removes the element at index 2

Upvotes: 1

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