Java LinkedList removeFirstOccurrence() Method

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Description

The Java LinkedList removeFirstOccurrence(Object) method removes the first occurrence of the specified element in this linkedList. This operation modifies the LinkedList instance.

Declaration

Following is the declaration for java.util.LinkedList.removeFirstOccurrence(o) method

public boolean removeFirstOccurrence(Object o)

Parameters

o − The element whose first occurrence is to be removed from this linkedList, if present.

Return Value

This method returns true if the linkedList contains the specified element.

Exception

NA

Removing First Occurence of Element from a LinkedList of Integers Example

The following example shows the usage of Java LinkedList removeFirstOccurrence() method with Integers. We're creating an LinkedList of Integers, adding some elements, print it and then use removeFirstOccurrence() method to remove first occurence of an element. As LinkedList is modified it is printed to check if first occurence of that element is removed or not.

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {
      
      // create an empty linkedList
      LinkedList<Integer> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add(25);
      linkedList.add(30);
      linkedList.add(20);
      linkedList.add(18);  
      linkedList.add(20);      

      // let us print all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);

      // it will remove first occurrence of element
      System.out.println("Element removed : " + linkedList.removeFirstOccurrence(20));
	  
      // let us print all the elements available in linkedList again
      System.out.println("LinkedList = " + linkedList);
   }
}

Output

Let us compile and run the above program, this will produce the following result −

LinkedList = [25, 30, 20, 18, 20]
Element removed : true
LinkedList = [25, 30, 18, 20]

Removing First Occurence of an Element from a LinkedList of Strings Example

The following example shows the usage of Java LinkedList removeFirstOccurrence() method with Strings. We're creating an LinkedList of Strings, adding some elements, print it and then use removeFirstOccurrence() method to remove first occurence of an element. As LinkedList is modified it is printed to check if first occurence of that element is removed or not.

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {
      
      // create an empty linkedList
      LinkedList<String> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add("A");
      linkedList.add("B");
      linkedList.add("C");
      linkedList.add("D");   
      linkedList.add("C");	  

      // let us print all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);

      // it will remove first occurrence of element
      System.out.println("Element removed : " + linkedList.removeFirstOccurrence("C"));
	  
      // let us print all the elements available in linkedList again
      System.out.println("LinkedList = " + linkedList);
   }
}

Output

Let us compile and run the above program, this will produce the following result −

LinkedList = [A, B, C, D, C]
Element removed : true
LinkedList = [A, B, D, C]

Removing First Occurence of an Element from a LinkedList of Objects Example

The following example shows the usage of Java LinkedList removeFirstOccurrence() method with Student objects. We're creating an LinkedList of Student objects, adding some elements, print it and then use removeFirstOccurrence() method to remove first occurence of an element. As LinkedList is modified it is printed to check if first occurence of that element is removed or not.

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {
      
      // create an empty linkedList
      LinkedList<Student> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add(new Student(1, "Julie"));
      linkedList.add(new Student(2, "Robert"));
      linkedList.add(new Student(3, "Adam"));       
      linkedList.add(new Student(2, "Robert"));
	  
      // let us print all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);

      // it will remove first occurrence of element
      System.out.println("Element removed : " + linkedList.removeFirstOccurrence(new Student(2, "Robert")));
	  
      // let us print all the elements available in linkedList again
      System.out.println("LinkedList = " + linkedList);
   }
}
class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
   
   @Override
   public boolean equals(Object obj) {
      Student s = (Student)obj;
      return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name);
   }
}

Output

Let us compile and run the above program, this will produce the following result −

LinkedList = [[ 1, Julie ], [ 2, Robert ], [ 3, Adam ], [ 2, Robert ]]
Element removed : true
LinkedList = [[ 1, Julie ], [ 3, Adam ], [ 2, Robert ]]