Question

好吧，看，我知道这个问题已经一次又一次得到回答但是我真的无法弄清楚我做错了什么。

请帮忙。

我有两节课。 Machine.java是对象类，InventoryTest.java类包含主语句。

我读到的任何地方都说这应该有用。

这是在Machine.java类

中

public static Comparator<Machine> machineIdNumberComparator = new Comparator<Machine>() {

    @Override
public int compare(Machine s1, Machine s2) {
   String MachineID1 = s1.getMachineIdNumber();
   String MachineID2 = s2.getMachineIdNumber();

   //ascending order
   return MachineID1.compareTo(MachineID2);
}};

这是在InventoryTest

中

        Collections.sort(arraylist, inventoryArray.machineIdNumberComparator);

这一行出现了问题。 arraylist找不到符号错误，machineIdNumberComparator也是如此。

我需要能够通过3种不同的方法进行排序。

编辑：这是我添加和创建我的arrayList

的方法

public List<Machine> inventoryArray = new ArrayList<>();

inventoryArray.add(new Machine(strMachineIdNumber, strManufacturer, strType, dblPowerOrCapacity, dblPrice));

arraylist在公共类的开头声明，你声明所有的变量。

/**
*
* @author stephankranenfeld
*/
import java.awt.*;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Collections;
import java.util.Comparator;
import java.util.NoSuchElementException;
import java.util.Scanner;
import java.util.StringTokenizer;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.*;
import javax.swing.JButton;
import javax.swing.JTextArea;

public class InventoryTest extends JFrame {

private static final int FRAME_WIDTH = 800;
private static final int FRAME_HEIGHT = 1500;
private final JTextArea textArea;
private final JButton addMachine;
private final JButton removeMachine;
private final JButton exitButton;
private final JButton sortButton;
final String START_TEXT = String.format("%-20s %-20s %-10s %15s %10s %n", "Machine ID Number:", "Manufacturer:", "Type:", "Power/Capacity:", "Price:"); // starting line of texted used in both display all and entre data buttons.
final String DEVIDER = "-------------------------------------------------------------------------------------\n";// a devider used multple times
public List<Machine> inventoryArray = new ArrayList<>();

 /*
junk that isn't needed i think
*/

private void sort() {
    JComboBox sortBy = new JComboBox();
    sortBy.addItem("ID Number");
    sortBy.addItem("Manufacturer");
    sortBy.addItem("Type");

    int option = JOptionPane.showConfirmDialog(null, sortBy, "Sort by?", JOptionPane.OK_CANCEL_OPTION);
    if (option == JOptionPane.OK_OPTION) 
    {
        //if id is selected sort by id
        //if manufacturer is selected sor by manufacturer
        //if type is selected sort by type
        Collections.sort(inventoryArray, Machine.machineIdNumberComparator);
    }
}
}


 public class Machine{
/*
* all the get and set methods
*/
    public static Comparator<Machine> machineIdNumberComparator = new Comparator<Machine>() {

    @Override
public int compare(Machine s1, Machine s2) {
   String MachineID1 = s1.getMachineIdNumber();
   String MachineID2 = s2.getMachineIdNumber();

   //ascending order
   return MachineID1.compareTo(MachineID2);
}};

Answer 1

Collections.sort()的第二个参数应为Machine.machineIdNumberComparator

用比较器排序Java

1 个答案: