LinkedList search

In this chapter you will learn:

What are the methods from LinkedList we can use to do a search
How to use the return value from indexOf and lastIndexof
If contain a certain element

Methods to do the search

int indexOf(Object o)
Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
int lastIndexOf(Object o)
Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.

import java.util.LinkedList;
/*from   j ava2s. c  om*/
public class Main{
    public static void main(String args[]) {
        LinkedList<String> ll = new LinkedList<String>();

        ll.add("A");
        ll.add("java2s.com");
        ll.add("B");
        ll.add("C");
        ll.add("java2s.com");


        System.out.println(ll.indexOf("java2s.com"));
        System.out.println(ll.lastIndexOf("java2s.com"));

    }
}

The output:

Return value from indexOf and lastIndexof

The following code uses indexOf and lastIndexOf to search elements in a LinkedList and check the return value.

import java.util.LinkedList;
/*  j av a2 s  .co m*/
public class Main {
  public static void main(String[] args) {
    LinkedList lList = new LinkedList();
    lList.add("1");
    lList.add("2");
    lList.add("3");
    lList.add("4");
    lList.add("5");
    lList.add("java2s.com");
    int index = lList.indexOf("2");
    if (index != -1) {
      System.out.println("First index of 2: " + index);
    } else {
      System.out.println("LinkedList does not contain 2");
    }
    index = lList.lastIndexOf("2");
    if (index != -1) {
      System.out.println("Last index of 2: " + index);
    } else {
      System.out.println("LinkedList does not contain 2");
    }
  }
}

The output:

If contain a certain element

boolean contains(Object o) Returns true if this list contains the specified element.

import java.util.LinkedList;
//  j av a2s  .  c  o m
public class Main{
    public static void main(String args[]) {

        LinkedList<String> ll = new LinkedList<String>();


        ll.add("B");
        ll.add("ja v a2s.com");
        ll.addLast("E");
        ll.add("F");


        boolean b = ll.contains("ja v a2s.com");
        System.out.println(b);
    }
}