Swing-GUI GPA 計算器

Question

我正在開發一個應用程序，它將通過 MyPanel class 中的按鈕和文本框從用戶那里獲取信息。 到目前為止，這部分有效。 現在我想顯示用戶在 DisplayTable 面板中輸入的課程信息。 我希望每次按下 MyPanel class 中的添加課程按鈕時它都會更新。 我嘗試將 function 添加到 DisplayTable 以在每次按下按鈕時添加 label 但我無法讓它工作，因為一個是 static 而一個不是。 關於如何做到這一點的任何想法？（或者關於如何改進應用程序的任何提示：））

Class 主要

public class Main {
    //TODO
    // PREVENT TYPE MISMATCH IN TEXT FIELDS
    // DISPLAY A TABLE OF COURSE NAMES - COURSE CREDITS - COURSE NAME AND THE GPA
    public static void main(String[] args) {
        new MyFrame();
    }
}

Class MyFrame

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class MyFrame extends JFrame{

    MainPanel mainPanel;

    MyFrame(){
        mainPanel = new MainPanel();

        this.add(mainPanel);
        this.setTitle("GPA Calculator");
        this.setResizable(false);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setSize(500,500);
        this.pack();
        this.setLocationRelativeTo(null);

        this.setVisible(true);
    }

}

Class 主面板

import javax.swing.*;

public class MainPanel extends JPanel {

    MyPanel myPanel = new MyPanel();
    DisplayPanel displayPanel = new DisplayPanel();

    MainPanel() {
        this.add(myPanel);
        this.add(displayPanel);
    }
}

Class 顯示面板

import javax.swing.*;
import java.awt.*;

public class DisplayPanel extends JPanel {

    static JLabel addLabel = new JLabel();

    public DisplayPanel() {
        this.setPreferredSize(new Dimension(500, 500));
        this.setBackground(new Color(0xEED2CC));
        this.setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
    }

    public static void addElements(String courseName, int courseCredits, double courseGrade) {
        addLabel.setText(courseName + " " + courseCredits + " " + courseGrade);
        addLabel.setText("");
    }

}

Class 我的面板

import javax.swing.*;
import javax.swing.Timer;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.*;
import java.util.List;

public class MyPanel extends JPanel implements ActionListener{

    List<String> courseNames;
    List<Integer> courseCredits;
    List<Double> courseGrades;
    Thread thread;
    JLabel nameLabel;
    JLabel creditLabel;
    JLabel gradeLabel;
    JTextField nameField;
    JTextField creditField;
    JTextField gradeField;
    JButton calculateButton;
    JButton addCourseButton;
    JButton resetButton;
    JLabel message;


    double result = 0;
    int tempInt = 0;
    double tempDouble = 0;

    MyPanel() {

        message = new JLabel();
        message.setHorizontalAlignment(JLabel.CENTER);
        message.setFont(new Font("Helvetica Neue", Font.PLAIN, 35));
        message.setForeground(new Color(0xA1683A));
        message.setAlignmentX(JLabel.CENTER_ALIGNMENT);

        courseNames = new ArrayList();
        courseCredits = new ArrayList();
        courseGrades = new ArrayList();

        nameLabel = new JLabel();
        nameLabel.setHorizontalAlignment(JLabel.CENTER);
        nameLabel.setText("Course Name");
        nameLabel.setFont(new Font("Helvetica Neue", Font.PLAIN, 25));
        nameLabel.setForeground(new Color(0xA1683A));
        nameLabel.setAlignmentX(JLabel.CENTER_ALIGNMENT);

        nameField = new JTextField();
        nameField.setPreferredSize(new Dimension(300,30));
        nameField.setMaximumSize(nameField.getPreferredSize());

        creditLabel = new JLabel();
        creditLabel.setHorizontalAlignment(JLabel.CENTER);
        creditLabel.setText("Course Credits(ECTS)");
        creditLabel.setFont(new Font("Helvetica Neue", Font.PLAIN, 25));
        creditLabel.setForeground(new Color(0xA1683A));
        creditLabel.setAlignmentX(JLabel.CENTER_ALIGNMENT);

        creditField = new JTextField();
        creditField.setPreferredSize(new Dimension(300,30));
        creditField.setMaximumSize(creditField.getPreferredSize());

        gradeLabel = new JLabel();
        gradeLabel.setHorizontalAlignment(JLabel.CENTER);
        gradeLabel.setText("Your Grade");
        gradeLabel.setFont(new Font("Helvetica Neue", Font.PLAIN, 25));
        gradeLabel.setForeground(new Color(0xA1683A));
        gradeLabel.setAlignmentX(JLabel.CENTER_ALIGNMENT);

        gradeField = new JTextField();
        gradeField.setPreferredSize(new Dimension(300,30));
        gradeField.setMaximumSize(gradeField.getPreferredSize());


        resetButton = new JButton("Reset");
        resetButton.setAlignmentX(JLabel.CENTER_ALIGNMENT);
        resetButton.addActionListener(this);
        addCourseButton = new JButton("Add Course");
        addCourseButton.setAlignmentX(JLabel.CENTER_ALIGNMENT);
        addCourseButton.addActionListener(this);
        calculateButton = new JButton("Calculate GPA");
        calculateButton.setAlignmentX(JLabel.CENTER_ALIGNMENT);
        calculateButton.addActionListener(this);

        //spacing and adding the elements
        this.add(Box.createRigidArea(new Dimension(0,20)));
        this.add(nameLabel);
        this.add(Box.createRigidArea(new Dimension(0,10)));
        this.add(nameField);
        this.add(Box.createRigidArea(new Dimension(0,20)));
        this.add(creditLabel);
        this.add(Box.createRigidArea(new Dimension(0,10)));
        this.add(creditField);
        this.add(Box.createRigidArea(new Dimension(0,20)));
        this.add(gradeLabel);
        this.add(Box.createRigidArea(new Dimension(0,10)));
        this.add(gradeField);
        this.add(Box.createRigidArea(new Dimension(0,20)));
        this.add(addCourseButton);
        this.add(Box.createRigidArea(new Dimension(0,5)));
        this.add(calculateButton);
        this.add(Box.createRigidArea(new Dimension(0,5)));
        this.add(resetButton);
        this.add(Box.createRigidArea(new Dimension(0,30)));
        this.add(message);
        this.setPreferredSize(new Dimension(500, 500));
        this.setBackground(new Color(0xEED2CC));
        this.setLayout(new BoxLayout(this,BoxLayout.Y_AXIS));
    }

    //calculate the GPA
    public double calculateGPA(){
        for (Integer courseCredit : courseCredits) {
            tempInt += courseCredit;
        }
        for(int i = 0; i<courseGrades.size();i++){
            tempDouble += courseGrades.get(i) * courseCredits.get(i);
        }
        return tempDouble/tempInt;
    }

    //create labels to display on the table
    public void createLabel(){

    }

    @Override
    public void actionPerformed(ActionEvent e) throws NumberFormatException {

        if(e.getSource().equals(addCourseButton)){

            //add items from the textFields to lists
            String tempText = nameField.getText();
            int tempCredit = Integer.parseInt(creditField.getText());
            double tempGrade = Double.parseDouble(gradeField.getText());
            courseNames.add(tempText);
            courseCredits.add(tempCredit);
            courseGrades.add(tempGrade);

            //set textFields to empty
            nameField.setText("");
            creditField.setText("");
            gradeField.setText("");

            //display a message for 3 seconds
            thread = new Thread();
            thread.start();
            message.setText("Course Added Successfully!");
            Timer timer = new Timer(3000, a -> message.setText(null));
            timer.setRepeats(false);
            timer.start();

            //add to table panel
            DisplayPanel.addElements(){

            }

        }

        //calculate the GPA, initialize the display panel
        //to display the courses names-credits-results and the gpa
        //as a table
        if(e.getSource().equals(calculateButton)){
            result = calculateGPA();
            message.setText(result + "");
        }

        //clear the lists,text fields and the message
        //get rid of the table panel
        if(e.getSource().equals(resetButton)){
            courseNames.clear();
            courseGrades.clear();
            courseCredits.clear();
            nameField.setText("");
            creditField.setText("");
            gradeField.setText("");
            message.setText(null);
        }
    }
}

Answer 1

您似乎在不需要的情況下使用了 static。

static JLabel addLabel = new JLabel();

使上述非靜態，（理想情況下也設為私有）

public static void addElements

使上述非 static 也，重命名為 setLabelText

DisplayPanel displayPanel = new DisplayPanel();
MyPanel myPanel = new MyPanel(displayPanel);

如上所示，將 displayPanel 作為參數傳遞給 myPanel。 顯然，在 MyPanel 中，您將擁有另外一個實例變量：

DisplayPanel displayPanel;

這將在構造函數中初始化。

在 MyPanel#actionPerformed 中，而不是：

//add to table panel
DisplayPanel.addElements(){
}

做：

displayPanel.addElements(....);

更確切地說

displayPanel.setLabelText(...);

在成績計算和重置時調用 DisplayPanel#setLabelText 方法。

同時調用

最后，刪除行：

addLabel.setText("");

如果你想要DisplayPanel，那為什么還要有以下呢？

public void createLabel(){