Java LinkedList programs and expected output

Last updated: 28 Sept 20263 min read

tutorial

A complete LinkedList program makes mutation order visible through its printed results.

Endpoint queue

import java.util.LinkedList;

public class TaskQueueDemo {
    public static void main(String[] args) {
        LinkedList<String> pendingTasks = new LinkedList<>();
        pendingTasks.addLast("Validate invoice");
        pendingTasks.addLast("Send receipt");
        pendingTasks.addFirst("Check account");
        System.out.println(pendingTasks);
        System.out.println(pendingTasks.pollFirst());
        System.out.println(pendingTasks.peekFirst());
        System.out.println(pendingTasks.size());
    }
}

[Check account, Validate invoice, Send receipt]
Check account
Validate invoice
2

Insertion after a matching stage

import java.util.Arrays;
import java.util.LinkedList;
import java.util.ListIterator;

public class ListEditDemo {
    public static void main(String[] args) {
        LinkedList<String> stages = new LinkedList<>(
            Arrays.asList("Received", "Packed", "Dispatched"));
        ListIterator<String> cursor = stages.listIterator();
        while (cursor.hasNext()) {
            if ("Packed".equals(cursor.next())) {
                cursor.add("Quality checked");
                break;
            }
        }
        System.out.println(stages);
    }
}

[Received, Packed, Quality checked, Dispatched]

The queue uses endpoints. The stage editor locates a matching value before it inserts. Both return an ordered sequence, but their costs differ because the second program searches.

Connected lessons

Continue with Java LinkedList: operations, internals and failure cases, Java LinkedList quiz.

Common Mistakes

Compile each public class in a file of the same name. These examples are single-threaded. Do not mistake printed output for a persistence or delivery guarantee.

java

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