Java CopyOnWriteArrayList indexOf() Method

The indexOf() method of java CopyOnWriteArrayList class returns the index of the first occurrence of the specified element in this list at position index or later in the list. If the element is not found, this method will return -1.

Syntax:

Parameters:

e ? It is the element to search

index ? It is the index to start searching

Returns:

This method returns the index of the first occurrence of the element in this list at position index. If the element is not found, this method will return -1.

Example 1

import java.util.concurrent.CopyOnWriteArrayList;

public class CopyOnWriteArrayListIndexOfExample1{
	
	public static void main(String[] args) {
		//Initializing CopyOnWriteArrayList of Integers
		CopyOnWriteArrayList<Integer>numbers = new CopyOnWriteArrayList<>(new Integer[] {1,2,1,4,5,3,3,3});
		//Prints index of the first occurrence of the element in this list at position index or later in the list and  -1 if the element is not found.
		System.out.println("Index of 3 is : " + numbers.indexOf(3, 1));
		
			}	
	}

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Output:

Index of 3 is : 5

Example 2

import java.util.concurrent.CopyOnWriteArrayList;

public class CopyOnWriteArrayListIndexOfExample2{
	
	public static void main(String[] args) {
		//Initializing CopyOnWriteArrayList of Integers
		CopyOnWriteArrayList<Integer>numbers = new CopyOnWriteArrayList<>(new Integer[] {1,2,1,4,5,3,3,3});
		//Prints index of the first occurrence of the element in this list at position index or later in the list and  -1 if the element is not found.
		System.out.println("Index of 9 is : " + numbers.indexOf(9, 1));
				}
		}

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Output:

Index of 9 is : -1

Example 3

import java.util.concurrent.CopyOnWriteArrayList;

public class CopyOnWriteArrayListIndexOfExample3{
	
	public static void main(String[] args) {
		//Initializing CopyOnWriteArrayList of Strings
		CopyOnWriteArrayList<String>listOfNames = new CopyOnWriteArrayList<>(new String[] {"Tom","Harry","John","John"});
		//Prints index of the first occurrence of the element in this list at position index or later in the list and  -1 if the element is not found.
		System.out.println("Index of John is : " + listOfNames.indexOf("John", 1));
		
			}
		}

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Output:

Index of John is : 2

Example 4

import java.util.concurrent.CopyOnWriteArrayList;

public class CopyOnWriteArrayListIndexOfExample4{
	
	public static void main(String[] args) {
		//Initializing CopyOnWriteArrayList of Strings
		CopyOnWriteArrayList<String>listOfNames = new CopyOnWriteArrayList<>(new String[] {"Tom","Harry","John","John"});
		//Prints index of the first occurrence of the element in this list at position index or later in the list and  -1 if the element is not found.
		System.out.println("Index of Jerry is : " + listOfNames.indexOf("Jerry", 1));
		
			}
	}

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Output: