我试图为游戏创建一个启动器，让我们说PowerTown。但是当我尝试为按钮创建一个ActionListener时，它表示无法从静态上下文引用非静态变量。我该如何解决这个问题？
package powertown;
import java.io.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class PowerTown {
/**
* @param args the command line arguments
*/
public static void main(String[] args)
implements ActionListener; {
//Start Varibles
String path = ClassLoader.getSystemClassLoader().getResource(".").getPath();
if (!new File(path + "PowerTownSave.txt").exists()) {
System.out.println("Creating save file...");
File f = new File(path + "PowerTownSave.txt");
f.getParentFile().mkdirs();
try {
f.createNewFile();
try {
BufferedWriter out = new BufferedWriter(new FileWriter(path + "PowerTownSave.txt"));
out.write("Coals \n");
out.newLine();
out.write("1 \n");
out.newLine();
out.write("Oils \n");
out.newLine();
out.write("0 \n");
out.newLine();
out.write("Bios \n");
out.newLine();
out.write("0 \n");
out.newLine();
out.write("Winds \n");
out.newLine();
out.write("0 \n");
out.newLine();
out.write("Sols \n");
out.newLine();
out.write("0 \n");
out.newLine();
out.write("Nukes \n");
out.newLine();
out.write("0 \n");
out.newLine();
out.write("Money \n");
out.newLine();
out.write("50 \n");
out.newLine();
out.write("Power \n");
out.newLine();
out.write("0 \n");
out.newLine();
out.write("Customers \n");
out.newLine();
out.write("5 \n");
out.newLine();
out.write("Storage \n");
out.newLine();
out.write("10 \n");
out.newLine();
out.write("AvgUse \n");
out.newLine();
out.write("1 \n");
out.newLine();
out.write("Time \n");
out.newLine();
out.write("0 \n");
out.newLine();
out.write("Reputation \n");
out.newLine();
out.write("0 \n");
out.newLine();
out.write("Protests \n");
out.newLine();
out.write("0 \n");
out.newLine();
out.write("Coal Supply \n");
out.newLine();
out.write("800 \n");
out.newLine();
out.write("Coal Demand \n");
out.newLine();
out.write("30 \n");
out.newLine();
out.write("Oil Supply \n");
out.newLine();
out.write("100 \n");
out.newLine();
out.write("Oil Demand \n");
out.newLine();
out.write("9 \n");
out.newLine();
out.write("Bio Supply \n");
out.newLine();
out.write("7 \n");
out.newLine();
out.write("Bio Demand \n");
out.newLine();
out.write("3 \n");
out.newLine();
out.write("Nukes Supply \n");
out.newLine();
out.write("5 \n");
out.newLine();
out.write("Nukes Demand \n");
out.newLine();
out.write("3 \n");
out.newLine();
out.write("Disaster probrobility \n");
out.newLine();
out.write("0");
out.newLine();
out.close();
} catch (IOException e) {
System.out.println("Failed to create save file, check your permisions. Are you admin? Are you root?");
}
} catch (IOException e) {
System.out.println("Failed to create save file, check your permisions. Are you admin? Are you root?");
return;
}
} else {
System.out.println("Save file found!");
}
System.out.println("Current readout of file will proceed, if file is empty, go to " + path + " , and then delete that file. After that, rerun the program.");
try (BufferedReader br = new BufferedReader(new FileReader(path + "PowerTownSave.txt"))) {
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
sb.append(line);
sb.append(System.lineSeparator());
line = br.readLine();
}
String fileReadout = sb.toString();
System.out.println(fileReadout);
} catch (IOException e) {
}
System.out.println("Startup save pickup has finished.");
System.out.println("Attemptng to create a launch window... Please wait.");
JFrame frame = new JFrame("PwrTwn Launcher");
System.out.println("Created new frame!");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
System.out.println("Set to terminate when closed...");
JButton startButton = new JButton("Launch");
startButton.addActionListener(this);
System.out.println("Created new JButton!");
startButton.setVerticalTextPosition(AbstractButton.BOTTOM);
startButton.setHorizontalTextPosition(AbstractButton.CENTER);
System.out.println("Set alignment for JButton!");
frame.setPreferredSize(new Dimension(300, 150));
System.out.println("Set Frame size!");
startButton.setSize(new Dimension(60, 20));
System.out.println("Set JButton size!");
frame.getContentPane().add(startButton, BorderLayout.CENTER);
System.out.println("Packaging...");
frame.pack();
frame.setVisible(true);
System.out.println("Launch window created!");
}
public void actionPerformed(ActionEvent e) {
//some witty stuff goes here
}
}
答案 0 :(得分：1)
您正尝试在方法上实施interface。这不可能做到并且没有任何意义（因为方法不能包含其他方法）。
您必须使用类作为ActionListener的基类，例如：
class PowerTown implements ActionListener {
@Override public void actionPerformed(ActionEvent event) {
...
}
public static void main(String[] args) {
PowerTown listener = new PowerTown();
startButton.addActionListener(listener);
}
}
但这是一个奇怪的设计，最好的解决方案是直接扩展JFrame并将行为嵌入其中：
class PowerTownFrame extends JFrame implements ActionListener {
public PowerTownFrame() {
JButton button = new JButton("test");
button.addActionListener(this);
...
}
@Override public void actionPerformed(ActionEvent event) {
...
}
public static void main(String[] args) {
PowerTownFrame frame = new PowerTownFrame();
frame.setVisible(true);
}
}
答案 1 :(得分：1)
您需要导入import java.awt.event.ActionListener;
public static void main(String[] args) implements ActionListener; {
方法不实现接口，类做。所以解决它：
public class PowerTown implements ActionListener {
startButton.addActionListener(this);
this无法在static方法中使用。您在main方法中使用此引用。相反，您可以创建类的实例并传递它。如下所示。
PowerTown powerTown = new PowerTown();
startButton.addActionListener(powerTown);