Stack indexOf() method in Java with Example

24 Dec, 2018
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

Java - util package
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