The Java.util.Stack.indexOf(Object element) method is used to check and find the occurrence of a particular element in the Stack. If the element is present then the index of the first occurrence of the element is returned otherwise -1 is returned if the Stack does not contain the element.
Syntax:
Stack.indexOf(Object element)
Parameters: This method accepts a mandatory parameter element of the type of Stack. It specifies the element whose occurrence is needed to be checked in the Stack.
Return Value: This method returns the index or position of the first occurrence of the element in the Stack. Else it returns -1 if the element is not present in the Stack. The returned value is of integer type.
Below programs illustrate the Java.util.Stack.indexOf() method:
Program 1:
// Java code to illustrate indexOf()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 in the Stack stack.add("Geeks"); stack.add("for"); stack.add("Geeks"); stack.add("10"); stack.add("20"); // Displaying the Stack System.out.println("Stack: " + stack); // The first position of an element // is returned System.out.println("The first occurrence" + " of Geeks is at index:" + stack.indexOf("Geeks")); System.out.println("The first occurrence" + " of 10 is at index: " + stack.indexOf("10")); }} |
Stack: [Geeks, for, Geeks, 10, 20] The first occurrence of Geeks is at index:0 The first occurrence of 10 is at index: 3
Program 2:
// Java code to illustrate indexOf()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 in the Stack stack.add(1); stack.add(2); stack.add(3); stack.add(10); stack.add(20); // Displaying the Stack System.out.println("Stack: " + stack); // The first position of an element // is returned System.out.println("The first occurrence" + " of Geeks is at index:" + stack.indexOf(2)); System.out.println("The first occurrence" + " of 10 is at index: " + stack.indexOf(20)); }} |
Stack: [1, 2, 3, 10, 20] The first occurrence of Geeks is at index:1 The first occurrence of 10 is at index: 4
