java - 错误: Main method not found in class mainGUI,请将main方法定义为:public static void main(String[] args)

Question

我正在用 java 创建 GUI 并收到以下错误:

Error: Main method not found in class mainGUI, please define the main method as:
public static void main(String[] args)

考虑到我的代码中确实有一个 main 方法并且它确实包含一些代码，我无法弄清楚为什么会发生这种情况。我的GUI代码如下:

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;


public class mainGUI extends JFrame {

/**
 * 
 */
private static final long serialVersionUID = 1L;

private static final int WIDTH = 400;
private static final int HEIGHT = 300;

private JLabel lengthL, widthL, areaL, perimeterL;
private JTextField lengthTF, widthTF, areaTF, perimeterTF;
private JButton calculateB, exitB;

private CalculateButtonHandler cbHandler;
private ExitButtonHandler ebHandler;

public mainGUI() {

    lengthL = new JLabel("Enter the length: ", SwingConstants.RIGHT);
    widthL = new JLabel("Enter the width: ", SwingConstants.RIGHT);
    areaL = new JLabel("Area: ", SwingConstants.RIGHT);
    perimeterL = new JLabel("Perimeter: ", SwingConstants.RIGHT);

    lengthTF = new JTextField(10);
    widthTF = new JTextField(10);
    areaTF = new JTextField(10);
    calculateB = new JButton("Calculate");
    cbHandler = new CalculateButtonHandler();
    calculateB.addActionListener(cbHandler);
    exitB = new JButton("Exit");
    ebHandler = new ExitButtonHandler();
    exitB.addActionListener(ebHandler);

    lengthTF = new JTextField(10);
    widthTF = new JTextField(10);
    areaTF = new JTextField(10);
    perimeterTF = new JTextField(10);

    calculateB = new JButton("Calculate");
    exitB = new JButton("Exit");
    Container pane = getContentPane();
    pane.setLayout(new GridLayout(5, 2));

    pane.add(lengthL);
    pane.add(lengthTF);
    pane.add(widthL);
    pane.add(widthTF);
    pane.add(areaL);
    pane.add(areaTF);
    pane.add(calculateB);
    pane.add(exitB);

    setTitle("Main Menu");
    setSize(WIDTH, HEIGHT);
    setVisible(true);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
}

private class CalculateButtonHandler implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            double width, length, area;
            length = Double.parseDouble(lengthTF.getText()); //We use the     getText & setText methods to manipulate the data entered into those fields.
            width = Double.parseDouble(widthTF.getText());
            area = length * width;           
            areaTF.setText("" + area);
        }
    }

public class ExitButtonHandler implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            System.exit(0);
        }
}

public static void main(String[] args) {
        mainGUI rectObj = new mainGUI();
}     
}

有人能解释一下为什么会发生这种情况吗？

非常感谢:)

Answer 1

你的代码工作正常，尝试从命令行运行它，或者尝试重新安装 eclipse，因为它不是代码错误，而是环境错误。

如果这不起作用，请尝试重新创建它，从 main 开始，然后向上走，它应该查明 eclipse 发生故障的位置。

祝你好运!