Question

How to implement array push and pop in Java

Answer 1

import java.util.ArrayList;
import java.util.Arrays;

public class Program {
    static ArrayList<Integer> array = new ArrayList<>(Arrays.asList(1, 2, 3, 4));
    
    public static void push(int n) {
        array.add(n);
    }
    
    public static void pop() {
        array.remove(array.size() - 1);
    }
    
    public static void main(String[] args) {
        push(23);
        push(78);
        push(99);

        System.out.println(array);

        pop();
        pop();

        System.out.println(array);
    }
}
 
  
  
/*
run:
  
[1, 2, 3, 4, 23, 78, 99]
[1, 2, 3, 4, 23]
  
*/

 

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Answer 2

import java.util.ArrayList;
import java.util.Arrays;

public class Program {
    static ArrayList<Integer> array = new ArrayList<>();
    
    public static void push(int n) {
        array.add(n);
    }
    
    public static void pop() {
        array.remove(array.size() - 1);
    }
    
    public static void main(String[] args) {
        push(23);
        push(78);
        push(99);

        System.out.println(array);

        pop();
        pop();

        System.out.println(array);
    }
}
 
  
  
/*
run:
  
[23, 78, 99]
[23]
  
*/

 

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