在 Java 中设置框架

Question

我是 Java 的新手，我一直在尝试设置一个框架，但我的代码不起作用，要么是因为代码有误，要么是因为我的软件有问题。我正在使用 Eclipse。

所以这是我的代码：

package Frame;

import javax.swing.JFrame;


public class App {


 class FrameApp extends JFrame {

     public static void main(String[] args) {

        JFrame frame = new JFrame("FirstFrame");
        frame.setTitle("MFF");
        frame.setSize(300, 700);
        frame.setVisible(true);

     }  
  }

}

它returns

The method main cannot be declared static; static methods can only be declared in a static or top level type

Answer 1

问题是您在内部 class 中声明了 main 方法。这就是抛出的异常的意思。这对你有用。

package Frame;

import javax.swing.JFrame;

class FrameApp extends JFrame{
public FrameApp(String name){
super(name);
}
} 


public class App {


 public static void main(String[] args) {

    FrameApp frame = new FrameApp("FirstFrame");
    frame.setTitle("MFF");
    frame.setSize(300, 700);
    frame.setVisible(true);

 }  

}

尽情享受吧！ :)

Answer 2

你可以这样做，这不是扩展JFrame。

import javax.swing.JFrame;

public class App{
    public App() {
        JFrame frame = new JFrame("FirstFrame"); // This sets the title
        frame.setTitle("MFF"); // Then you're resetting the title
        frame.setSize(300, 700);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 }
    public static void main(String[] args) {
        new App();
    }

}

Or you can extend it

import javax.swing.JFrame;

public class App extends JFrame{
    public App() {
        // When you extend JFrame you're essentially creating a JFrame
        // This gets into OOP (which you of course need to learn)
        // Since you've extended the JFrame you can directly access its methods 
        // like setTitle, setSize....
        setTitle("MFF"); 
        setSize(300, 700);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 }
    public static void main(String[] args) {
        new App();
    }

}

I'm definitely not very experienced with Swing, but when choosing one approach over the other. I choose not to extend the Frame. And to answer your question, there's no reason to put another class within the App class when just creating this simple JFramethat is why I changed to the above.

在 Java 中设置框架

Setting up a frame in Java

java

frame