我正在開發一個應用程式，它將通過 MyPanel 類中的按鈕和文本框從用戶那里獲取資訊。到目前為止，這部分有效。現在我想顯示用戶在 DisplayTable 面板中輸入的課程資訊。我希望每次按下 MyPanel 類中的添加課程按鈕時它都會更新。我嘗試向 DisplayTable 添加一個函式，以便在每次按下按鈕時添加一個標簽，但我無法讓它作業，因為一個是靜態的，一個不是。關于如何做到這一點的任何想法？（或有關如何總體改進應用程式的任何提示:)）
主類
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();
}
}
類 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);
}
}
類主面板
import javax.swing.*;
public class MainPanel extends JPanel {
MyPanel myPanel = new MyPanel();
DisplayPanel displayPanel = new DisplayPanel();
MainPanel() {
this.add(myPanel);
this.add(displayPanel);
}
}
類 DisplayPanel
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("");
}
}
類 MyPanel
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);
}
}
}
uj5u.com熱心網友回復：
您似乎不需要使用靜態。
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
也使上述非靜態，重命名為 setLabelText
DisplayPanel displayPanel = new DisplayPanel();
MyPanel myPanel = new MyPanel(displayPanel);
如上所示，將 displayPanel 作為引數傳遞給 myPanel。顯然，在 MyPanel 中，您將擁有另外一個實體變數：
DisplayPanel displayPanel;
這將在建構式中初始化。
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呼叫 DisplayPanel#setLabelText 方法。
同時呼叫
最后，洗掉行：
addLabel.setText("");
如果你想要DisplayPanel，那為什么還要有以下呢？
public void createLabel(){
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