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
