Stack copyInto() method in Java with Example

The java.util.Stack.copyInto() method is used to copy all of the components from this Stack to another Stack, having enough space to hold all of the components of the Stack. It is to be noted that the index of the elements remains unchanged. The elements present in the Stack are replaced by the elements of the Stack.

Syntax:

Stack.copyInto(Object Stack[])

Parameters: The parameter Stack[] is of the type of Stack. This is the Stack into which the elements of the Stack are to be copied.

Return Value: The method is of void type and does not return any values.

Exception: The method throws NullPointerException if the Stack is NULL.

Below programs illustrates the Java.util.Stack.copyInto() method:

Program 1:

// Java code to illustrate copyInto()
import java.util.*;

public class StackDemo {
    public static void main(String args[])
    {
        // Creating an empty Stack
        Stack<String> stack = new Stack<String>();

        // Use add() method to add elements into the Stack
        stack.add("Welcome");
        stack.add("To");
        stack.add("Geeks");
        stack.add("4");
        stack.add("Geeks");

        // Displaying the Stack
        System.out.println("Stack: " + stack);

        // Creating an Stack
        String arr[] = new String[6];

        arr[0] = "Hello";
        arr[1] = "World";

        // Displaying the initial Stack
        System.out.println("The initial Stack is: ");
        for (String str : arr)
            System.out.println(str);

        // Copying
        stack.copyInto(arr);

        // The final Stack
        System.out.println("The final Stack is: ");
        for (String str : arr)
            System.out.println(str);
    }
}

Output:

Stack: [Welcome, To, Geeks, 4, Geeks]
The initial Stack is: 
Hello
World
null
null
null
null
The final Stack is: 
Welcome
To
Geeks
4
Geeks
null

Program 2:

// Java code to illustrate copyInto()
import java.util.*;

public class StackDemo {
    public static void main(String args[])
    {
        // Creating an empty Stack
        Stack<Integer> stack = new Stack<Integer>();

        // Use add() method to add elements into the Stack
        stack.add(10);
        stack.add(20);
        stack.add(30);
        stack.add(40);
        stack.add(50);

        // Displaying the Stack
        System.out.println("Stack: " + stack);

        // Creating an Stack
        Integer arr[] = new Integer[6];

        arr[0] = 50;
        arr[1] = 60;
        arr[2] = 70;
        arr[3] = 80;
        arr[4] = 90;

        // Displaying the initial Stack
        System.out.println("The initial Stack is: ");
        for (Integer str : arr)
            System.out.println(str);

        // Copying
        stack.copyInto(arr);

        // The final Stack
        System.out.println("The final Stack is: ");
        for (Integer str : arr)
            System.out.println(str);
    }
}

Output:

Stack: [10, 20, 30, 40, 50]
The initial Stack is: 
50
60
70
80
90
null
The final Stack is: 
10
20
30
40
50
null