按 int 变量对对象列表进行排序

Question

我有一个类 (ClassOne)，它有一个实例类 (Process) 的列表，我试图弄清楚如何根据它们的优先级对它们进行排序。

public class ClassOne
{
    static List<Process> processList = new ArrayList<Process>();

    public static void main(String[] args)
    {
        //hardcoded for example
        processList.add(new Process(3));
        processList.add(new Process(1));
        processList.add(new Process(2));
        
        The processes are current not ordered in the List by priority, so I call insertion sort
    }

    //Im pretty sure this is changing their priority instead of where they are in the List, but i dont know how to change it
    public static void InsertionSort()
    {
        int n = processList.size(); 
        for (int i = 1; i < n; ++i) 
        { 
            int key = processList.get(i).priority; 
            int j = i - 1; 
 
            /* Move elements of processList.get(0..i-1]).priority, that are 
               greater than key, to one position ahead 
               of their current position */
            while (j >= 0 && processList.get(j).priority > key)
            {
                processList.get(j+1).priority = processList.get(j).priority; 
                j = j - 1; 
            } 
            processList.get(j + 1).priority = key; 
        }

}

public class Process
{
    int priority;
    public Process(int tempPriority)
    {
        priority = tempPriority;
    }
}

任何排序方法都可以，我想按优先级从最小到最大对 processList 中的每个 Process 对象进行排序。

尝试第一个解决方案后的代码：

public static void InsertionSort()
    {
         System.out.println(processList.get(0).name);
         System.out.println(processList.get(1).name);
        int n = processList.size(); 
        for (int i = 1; i < n; ++i) 
        { 
            int key = processList.get(i).priority; 
            int j = i - 1; 
            //The method set(int, Process) in the type List<Process> is not applicable for the arguments (int, int)
            /* Move elements of processList.get(0..i-1]).priority, that are 
               greater than key, to one position ahead 
               of their current position */
            while (j >= 0 && processList.get(j).priority > key)
            {
                processList.set(j + 1, processList.get(j));
                j = j - 1; 
            } 
            processList.set(j + 1, processList.get(i));
            System.out.println("Queue Sorted");
            System.out.println(processList.get(0).name);
            System.out.println(processList.get(1).name);
            
        } 

Answer 1

使用 java 8+ 你可以试试下面的代码：

import java.util.*;
import java.util.stream.Collectors;
public static void InsertionSort()
{
    System.out.println(processList.get(0).name);
    System.out.println(processList.get(1).name);
    System.out.println(processList.get(2).name);
    
    processList=processList.stream()
    .sorted((o1,o2)->{return o1.priority-o2.priority;})
    .collect(Collectors.toList());
    
    System.out.println(processList.get(0).name);
    System.out.println(processList.get(1).name);
    System.out.println(processList.get(2).name);
}

Answer 2

使用List#set 在索引处设置元素。

processList.get(j+1).priority = processList.get(j).priority; 

变成

 processList.set(j+1, processList.get(j));

和

processList.get(j + 1).priority = key; 

变成

processList.set(j+1, processList.get(i));