How to use size method in java

import java.util.*;

public class size {

    public static void main(String[] args) {

        ArrayList a1 = new ArrayList();

        a1.add("1");

        a1.add("2");

        a1.add("3");

        System.out.println("\n ArrayList size is "+a1.size());

    }

}

Answer

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ArrayList size is 3