Java ArrayList indexOf example

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Methods:

ArrayList indexOf Example:

ArrayList‘s indexOf method is used to find out first index of object in arraylist.

indexOf method takes object as argument and returns first occurrence of specified element.

Methods:

public int indexOf(Object o)
returns index of first occurrence of element in the ArrayList.

indexOf method return -1 if object is not present in the ArrayList

ArrayList indexOf Example:

import java.util.ArrayList;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.*;
class IndexOfArrayListMain {
 /*
  * @author : Arpit Mandliya
  */
 public static void main(String[] args) {
  ArrayList employeeNameList = new ArrayList();
  employeeNameList.add("John");
  employeeNameList.add("Ankit");
  employeeNameList.add("Rohan");
  employeeNameList.add("Amit");

  System.out.println("Index of Ankit: "+employeeNameList.indexOf("Ankit"));
  System.out.println("*******************************");

  System.out.println("Index of John: "+employeeNameList.indexOf("John"));
  System.out.println("*******************************");
 // Arpit is not present in the list
  System.out.println("Index of Arpit: "+employeeNameList.indexOf("Arpit"));
 }
}

import java.util.ArrayList;

import java.util.HashSet;

import java.util.LinkedHashSet;

import java.util.*;

class IndexOfArrayListMain {

* @author : Arpit Mandliya

public static void main(String[] args) {

ArrayList employeeNameList = new ArrayList();

employeeNameList.add("John");

employeeNameList.add("Ankit");

employeeNameList.add("Rohan");

employeeNameList.add("Amit");

System.out.println("Index of Ankit: "+employeeNameList.indexOf("Ankit"));

System.out.println("*******************************");

System.out.println("Index of John: "+employeeNameList.indexOf("John"));

System.out.println("*******************************");

// Arpit is not present in the list

System.out.println("Index of Arpit: "+employeeNameList.indexOf("Arpit"));

}

When you run above program, you will get below output

Index of Ankit: 1
*******************************
Index of John: 0
*******************************
Index of Arpit: -1

Index of Ankit: 1

*******************************

Index of John: 0

*******************************

Index of Arpit: -1

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Java ArrayList indexOf example

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ArrayList indexOf Example:

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