在 Java 中使用按 ID 编号的链表升序

Question

So I have a list of items, with random ID numbers assigned to them. Those items then print out in a list. I need to able to print them out in ascending order. The constructor in the LinkedList class should call a method to build a list of test data. These should be added to the LinkedList in sorted order. Below is the code I need to edit to make this work:

public boolean decideToInsert (Makeup ee) {
boolean decision = false;
//code goes here
return decision;

Here is my linked list code:

package model;
import java.util.LinkedList;
import java.util.ListIterator;

public class MakeupList {

private LinkedList <Makeup> makeList = new LinkedList<>();
public MakeupList(){
    this.createMakeList();
    this.printMakeList();
}
public void createMakeList(){
    makeList.add(new Makeup("Natural Face", "Too Face"));

    for (int i = 0; i<10; i++){
        addMakeup (new Makeup ("Matte Lipstick", "MAC"));
}
}

public void addMakeup (Makeup newMake){
    boolean makeupAdded = false;
    boolean insertDecision = false;
    ListIterator<Makeup> makeIterator = makeList.listIterator();
    while (makeIterator.hasNext()){
        insertDecision = makeIterator.next().decideToInsert(newMake);
        if (insertDecision == true){
            makeList.add(makeIterator.previousIndex(), newMake);
            makeupAdded = true;
            break;
        } 
    }
    if(!makeupAdded){
        makeList.add(newMake);
    }
}
public void printMakeList(){
    ListIterator<Makeup> makeIterator = makeList.listIterator();
    while(makeIterator.hasNext()){
        System.out.println(makeIterator.next().toString());
        }
    }
}

Here is an example of what it is currently printing out: Makeup: Natural Face Too Face ID: 1

Makeup: Matte Lipstick MAC ID: 1

Makeup: Matte Lipstick MAC ID: 0

Makeup: Matte Lipstick MAC ID: 2

Makeup: Matte Lipstick MAC ID: 37

Makeup: Matte Lipstick MAC ID: 10

Makeup: Matte Lipstick MAC ID: 21

Makeup: Matte Lipstick MAC ID: 34

Makeup: Matte Lipstick MAC ID: 8

Makeup: Matte Lipstick MAC ID: 33

Makeup: Matte Lipstick MAC ID: 19

Answer 1

Your code is very complicated. You just add an id into your Makeup model and do a java stream sorting by comparator. More details are here: java 8, Sort list of objects by attribute without custom comparator

Answer 2

Try using:

Collections.sort(linkedlistVAR);

before you print it out. :-)

Answer 3

I don't quite understood your question. If Makeup has an id atribute and you wanna sort by it try sorting with the Comparator interface on the start of you print method.

Example: makeList.sort(Comparator.nullsFirst(Comparator.comparing(Makeup::getId, Comparator.nullsFirst(naturalOrder()))));