A Developer Gateway To IT World...

Techie Uncle Software Testing Core Java Java Spring C Programming Operating System HTML 5 Java 8 ES6 Project

LinkedList in Java

Add() method:-
Appends the specified element to the end of this list.
This method is equivalent to addLast.
Specified by: add(...) in List, add(...) in Deque, Overrides: add(...) in AbstractList
Parameters:
e element to be appended to this list
Returns:
true (as specified by Collection.add)

Example:-
import java.util.LinkedList;

public class TestLinkedListClass {

       public static void main(String[] args) {
      
             LinkedList<String> llist = new LinkedList<>();
             llist.add("programming");
             llist.add("shifts");
            
              System.out.println(llist);
            
       }
}

Sample Output

[programming, shifts]

Size() Method
Returns the number of elements in this list.
Specified by: size() in List, size() in Deque, Overrides: size() in AbstractCollection
Returns:
the number of elements in this list

import java.util.LinkedList;

public class TestLinkedListClass {

       public static void main(String[] args) {
      
             LinkedList<String> llist = new LinkedList<>();
             llist.add("programming");
             llist.add("shifts");
            
             int s=llist.size();
             System.out.println(s);
       }
}

SampleOut:
2

toArray() method:
Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array. If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this list.
If the list fits in the specified array with room to spare (i.e., the array has more elements than the list), the element in the array immediately following the end of the list is set to null. (This is useful in determining the length of the list only if the caller knows that the list does not contain any null elements.)
Like the toArray() method, this method acts as bridge between array-based and collection-based APIs.
Further, this method allows precise control over the runtime type of the output array, and may, under certain circumstances, be used to save allocation costs.
Suppose x is a list known to contain only strings. The following code can be used to dump the list into a newly allocated array of String:
     String[] y = x.toArray(new String[0]);
Note that toArray(new Object[0]) is identical in function to toArray().
Type Parameters:
<T> the runtime type of the array to contain the collection
Parameters:
a the array into which the elements of the list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.
Returns:
an array containing the elements of the list
Throws:
ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this list
NullPointerException - if the specified array is null

import java.util.LinkedList;

public class TestLinkedListClass {

       public static void main(String[] args) {
      
             LinkedList<String> llist = new LinkedList<>();
             llist.add("programming");
             llist.add("shifts");
            
             // create an array and copy the list to it
             Object[] array = llist.toArray(new Object[4]);

             // print the array
             for (int i = 0; i < llist.size(); i++) {
                System.out.println("Array:" + array[i]);
             }
       }
}

Sample Out:
Array:programming

Array:shifts



Traversing the list of elements in reverse order



import java.util.Iterator;
import java.util.LinkedList;

public class TestLinkedListClass {

       public static void main(String[] args) {
      
             LinkedList<String> llist = new LinkedList<>();
             llist.add("programming");
             llist.add("shifts");
            
              //Traversing the list of elements in reverse order 
        Iterator i=llist.descendingIterator(); 
        while(i.hasNext()) 
        { 
            System.out.println(i.next()); 
        } 
       }
}

Sampleoutput:
shifts

programming




addFirst Method:

Inserts the specified element at the beginning of this list.
Specified by: addFirst(...) in Deque
Parameters:
e the element to add

addLast Method
Appends the specified element to the end of this list.
This method is equivalent to add.
Specified by: addLast(...) in Deque
Parameters:
e the element to add

import java.util.Iterator;
import java.util.LinkedList;

public class TestLinkedListClass {

       public static void main(String[] args) {
      
             LinkedList<String> llist = new LinkedList<>();
             llist.add("programming");
             llist.add("shifts");
            
        llist.addFirst("www.");
        llist.addLast(".com");
       
        System.out.print(llist);
       }
}

SampleOutput
[www., programming, shifts, .com]













LEARN TUTORIALS

.

.