Java Swing Jcombobox/按钮编辑参数

Question

我对与Java的GUI合作是新手。例如，我正在尝试几件事，例如，使用运行方法中的以下命令添加新条目或更改JButtons字幕：

pwselection.additem("名称1"(;

dec_btn.setText(" example"(;

受保护的jcombobox pwselection =新的jcombobox(内容(;

不幸的是，一旦我启动该程序，它都没有显示出任何效果。布局是由Intellij GUI表单创建者制成的。如果您能给我任何提示或替代方法，那就太好了。

package PackMain;
import javax.swing.*;
public class Password {
    String[] contents = {"Name 1", "Name 2"};
    protected JTextField newAdress;
    protected JPanel panel1;
    protected JComboBox pwSelection = new JComboBox(contents); // ?
    protected JLabel title;
    protected JTextField pwOutput;
    protected JButton enc_btn;
    protected JButton dec_btn;
    public JFrame run(){
        JFrame mainFrame= new JFrame ("Password");
        mainFrame.setContentPane(new Password().panel1);
        mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        mainFrame.pack();
        mainFrame.setLocationRelativeTo(null);
        mainFrame.setSize(400, 200);
        mainFrame.setResizable(false);
        mainFrame.setVisible(true);
        pwSelection.addItem("Name 1");
        dec_btn.setText("Example");
        return mainFrame;
    }

    public static void main(String[] args){
        new Password().run();
    }

}

Answer 1

您没有在框架中添加任何面板，也没有初始化任何属性...

package password;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import javax.swing.*;
public class Password extends JFrame{
String[] contents = {"Name 1", "Name 2"};
protected JTextField newAdress;
protected JPanel panel1, panel2; //2 panels for a more organized approach...
protected JComboBox  pwSelection;// ?
protected JTextField pwOutput;
protected JButton enc_btn;
protected JButton dec_btn;
public Password(){          //Constructor of the class, initialize stuff here...
    super("Shinny title");
    //1. Initialize all your atributtes...
    newAdress = new JTextField();
    panel1 = new JPanel();
    panel2 = new JPanel();
    pwSelection = new JComboBox(contents);
    pwOutput= new JTextField();
    enc_btn = new JButton("First button");
    dec_btn = new JButton("Second Button");
    //Set layouts..
    panel1.setLayout(new GridLayout(3,1));          
panel2.setLayout(new FlowLayout());
    //Add items to panel 1...
    panel1.add(new JLabel("Adress:"));  //A more simple aproach for creating a label...
    panel1.add(newAdress);
    panel1.add(pwSelection);
    panel1.add(enc_btn);
    panel1.add(dec_btn);
    panel1.add(pwOutput);
    //Add items of panel 1 to panel 2...
    panel2.add(panel1);
    add(panel2);
    setSize(300,300);
    setVisible(true);
    //Proper way of stop the application at closing...
    this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
}
//This is not necessary as everything should be implemented in the constructor.
/*
public JFrame run(){
    JFrame mainFrame= new JFrame ("Password");
    mainFrame.setContentPane(new Password().panel1);
    mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    mainFrame.pack();
    mainFrame.setLocationRelativeTo(null);
    mainFrame.setSize(400, 200);
    mainFrame.setResizable(false);
    mainFrame.setVisible(true);
    pwSelection.addItem("Name 1");
    dec_btn.setText("Example");
    setVisible(true);
    return mainFrame;
}

*/

public static void main(String[] args){
    //Initialize the constructor...
    Password ps = new Password();
}

}

这将使您了解如何实现Java上的GUI。

Answer 2

panel1从未将其定义为新的jpanel((，因此它为null，并且您的所有其他组件 - pwselection，title等 - 从未添加到panel1。/p>