Java griddbaglayout组件没有全屏显示

Question

我是Java的新手，并试图用griddbaglayout生成我的第一个GUI。下面的代码，我得到我的全屏，但组件"label_url_eingabe"one_answers"url_eingabe"没有显示(空窗口)。当我最小化窗口时，它们就会显示出来!当我将窗口大小设置为特定值时，我得到了相同的行为。因此，这些组件在程序的初始开始时没有显示。

package ofb_reader_package;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
public class OFB_Reader_GUI extends JFrame {
// Definition der GUI Komponenten
    // Eingabefeld URL
    JLabel label_url_eingabe;
    JTextField url_eingabe;
    //this.OFB_Reader_GUI();
// Eigenschaften Hauptfenster "OFB_Reader_GUI"  
    public OFB_Reader_GUI() {
        // Eigenschaften Hauptfenster   
        setVisible(true);
        setSize(500, 300);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setTitle("Mark's OFB Reader");
        setResizable(true);
        setExtendedState(JFrame.MAXIMIZED_BOTH); 
        setLayout(null);


        this.label_url_eingabe = new JLabel("URL:");
        this.url_eingabe = new JTextField(10);
        this.getContentPane().setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();

        // POSITIONIERUNGEN MIT GRIDBAGLAYOUT
        // URL Eingabe Label und Einghabefeld 
        c.fill = GridBagConstraints.HORIZONTAL;
        c.gridx = 0;
        c.gridy = 0;
        c.ipadx = 35;
        c.weightx = 1.0;
        c.weighty = 1.0;
        c.anchor = GridBagConstraints.NORTHWEST;
        this.getContentPane().add(this.label_url_eingabe, c);

        c.fill = GridBagConstraints.HORIZONTAL;
        c.gridx = 1;
        c.gridy = 0;
        c.ipadx = 35;
        c.weightx = 1.0;
        c.weighty = 1.0;
        c.anchor = GridBagConstraints.NORTHWEST;
        add(this.url_eingabe, c);
    }   
}

this is the main:

package ofb_reader_package;
import javax.swing.*;

public class OFB_Reader_main_class {
    public static void main(String[] args){
        new OFB_Reader_GUI();
        new OFB_Reader_main_class();
    }
}

Answer 1

非常感谢您的帮助!!我想我现在明白了:

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

public class OFB_Reader_GUI_and_Main  {


    public static void addComponentsToPane(Container pane) {
        JLabel label_url_eingabe;
        JTextField url_eingabe;
        pane.setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();        
        label_url_eingabe = new JLabel("URL:");
        c.fill = GridBagConstraints.HORIZONTAL;
        c.gridx = 0;
        c.gridy = 0;
        pane.add(label_url_eingabe, c);
        url_eingabe = url_eingabe = new JTextField(10);
        c.fill = GridBagConstraints.HORIZONTAL;
        c.gridx = 1;
        c.gridy = 0;
        pane.add(url_eingabe, c);
    }
     private static void createAndShowGUI() {
        //Create and set up the window.
        JFrame frame = new JFrame("GridBagLayoutDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //Set up the content pane.
        addComponentsToPane(frame.getContentPane());
        //Display the window.
        frame.pack();
        frame.setVisible(true);
        }   



public static void main(String[] args){
    //Schedule a job for the event-dispatching thread:
    //creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            createAndShowGUI();
        }
    });
}
}