Question

所以基本上我有一个程序，我将pc添加到数组列表中，并且必须选择其中最好的一个（取决于分数/价格数学运算），这意味着得分为10的PC和价格5分比10分和10分的分数要好。问题是布尔（isBetterThan）方法必须实现，并以某种方式用于比较它们，我无法弄清楚究竟如何）。这是迄今为止的代码：

    package filipapp;

public interface Better {
    public double getPrice();
    public void setPrice(double price);
    public int getScore();
    public void setScore(int score);
    public boolean isBetterThan(Object obj);
}

类

    package filipapp;

public class Computer implements Better {
    private String model;
    private double price;
    private int score;
    public Computer (String model,double price,int score){
        this.model = model;
        this.price = price;
        this.score = score;
    }
    @Override 
    public double getPrice(){
        return price;
    }
    @Override
    public void setPrice(double price){
        this.price = price;
    }
    @Override 
    public int getScore(){
        return score;
    }
    @Override
    public void setScore(int score){
        this.score = score;
    }
    @Override 
    public boolean isBetterThan(Object obj){
        obj = getScore()/getPrice();
        return true;
    }
    @Override
    public String toString(){
        return ("Model "+model+" at price: "+price+" with score: "+score);
    }
}

GUI

 package filipapp;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class FilipApp extends JFrame implements ActionListener {
    private JLabel l1,l2,l3;
    private JTextField t1,t2,t3;
    private JPanel p1,p2,p3;
    private JButton b1,b2;
    private JTextArea area;
    private JScrollPane scroll;
    public Computer p;
    ArrayList <Computer> pc = null;

    public static void main(String[] args) {
         EventQueue.invokeLater(new Runnable(){
           @Override
           public void run(){
               new FilipApp().setVisible(true);
           }
       });
    }
    public FilipApp(){
        super("The best PC");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(600,400);
        Container container = this.getContentPane();

        p1 = new JPanel();
        p1.setLayout(new GridLayout(3,2));
        l1 = new JLabel("Model",JLabel.CENTER);
        p1.add(l1);
        t1 = new JTextField(15);
        p1.add(t1);
        l2 = new JLabel("Price",JLabel.CENTER);
        p1.add(l2);
        t2 = new JTextField(15);
        p1.add(t2);
        l3 = new JLabel("Score",JLabel.CENTER);
        p1.add(l3);
        t3 = new JTextField(15);
        p1.add(t3);
        container.add(p1,BorderLayout.PAGE_START);

        p2 = new JPanel();
        b1 = new JButton("Add");
        b1.addActionListener(this);
        p2.add(b1);
        b2 = new JButton("Best");
        b2.addActionListener(this);
        p2.add(b2);
        container.add(p2,BorderLayout.CENTER);

        p3 = new JPanel();
        area = new JTextArea(15,35);
        scroll = new JScrollPane(area ,JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
        p3.add(scroll);
        container.add(p3,BorderLayout.PAGE_END);

        pc = new ArrayList <>();
    }
    @Override
    public void actionPerformed(ActionEvent e){
        try{
            Object source = e.getSource();
            if (source == b1){
                p = new Computer(t1.getText(),Double.parseDouble(t2.getText()),Integer.parseInt(t3.getText()));
                pc.add(p);
                area.append("Added PC  \n"+p.toString()+"\n");
                t1.setText("");t2.setText("");t3.setText("");
            }
            else if (source == b2 && pc.isEmpty()){
                area.append("Empty List \n");
            }
            else if (source == b2){
              for (Computer element : pc){

                  element.isBetterThan(element);
                  area.append("Best PC: "+element.toString()); 
              }
            }
        }catch(NumberFormatException ex){
             System.out.println("Error in input data");
        }
    }
}

Answer 1

在yout循环中，您应该使用速度变量作为最佳项目。

       else if (source == b2){
          Computer best = pc.get(0); // Depend on your logic, you should verify if the pc list is empty or not before get(0)
          for (int i = 1; i < pc.size(); i++){
              Computer element = pc.get(i);
              if (element.isBetterThan(best)) {
                   best = element;
              }
          }
          // When loop exits, you have access to the best pc
          area.append("Best PC: "+best.toString()); 
        }

Answer 2

首先，如果它是更好的＆＃34;而另一个是主观的，我发现你使用getScore()/getPrice()进行判断，所以我会继续假设没问题。

首先要理解的是isBetterThan正在将this Computer对象与另一个计算机对象进行比较。所以启动界面应该看起来像

public boolean isBetterThan(Computer comp);

然后用你的除法逻辑来表示它看起来像

public boolean isBetterThan(Computer comp){
    if((this.getScore()/this.getPrice()) <
             comp.getScore()/comp.getPrice()) {
        return false;
    }
    return true;
}

Java - 比较ArrayList中对象的值

2 个答案: