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