从Java中的另一个类访问字符串

Question

这与常见问题稍有不同。我知道如果我可以将字符串设置为public static String passcode;，我会怎么做，但问题是我不能。我需要什么，我想在这里实现的解决方案：

public class EncryptionSubtask { 


public static void main(String[] args) { 
    Main m2 = new Main(); 
    m2.setVisible(true); 
    m2.setResizable(true); 
    m2.setLayout(new FlowLayout()); 
} 

public EncryptionSubtask() { 
    log("Running Substask"); 
    Random rand = new Random(); 
    int n1 = 33 + rand.nextInt(94); 
    int n2 = 33 + rand.nextInt(94); 
    int n3 = 33 + rand.nextInt(94); 
    int n4 = 33 + rand.nextInt(94); 
    int n5 = 33 + rand.nextInt(94); 
    int n6 = 33 + rand.nextInt(94); 
    int n7 = 33 + rand.nextInt(94); 
    int n8 = 33 + rand.nextInt(94); 

    String c1 = Character.toString ((char) n1); 
    String c2 = Character.toString ((char) n2); 
    String c3 = Character.toString ((char) n3); 
    String c4 = Character.toString ((char) n4); 
    String c5 = Character.toString ((char) n5); 
    String c6 = Character.toString ((char) n6); 
    String c7 = Character.toString ((char) n7); 
    String c8 = Character.toString ((char) n8); 


    String passcode = (c1+c2+c3+c4+c5+c6+c7+c8); 

    System.out.println(passcode); 

} 

如果我想要得到“密码”到这里：

public class Main extends Frame implements Runnable, KeyListener, MouseListener, WindowListener { 

private static final long serialVersionUID = 1L; 
Thread thread; 
BufferedImage backbuffer; 
Graphics2D g2d; 
AffineTransform transform = new AffineTransform(); 

enum Modes { 
    Menu, Encrypt, Decrypt 
} 

Modes mode = Modes.Menu; 

public Image background; 

public static void main(String[] args) { 
    Main m = new Main(); 
    m.setVisible(true); 
    m.setResizable(true); 
    m.setLayout(new FlowLayout()); 
} 

@Override 
public void windowActivated(WindowEvent e) { 
} 

@Override 
public void windowClosed(WindowEvent e) { 
} 

@Override 
public void windowClosing(WindowEvent e) { 
    dispose(); 
    log("Exiting..."); 
    System.exit(0); 
} 

@Override 
public void windowDeactivated(WindowEvent e) { 
} 

@Override 
public void windowDeiconified(WindowEvent e) { 
} 

@Override 
public void windowIconified(WindowEvent e) { 
} 

@Override 
public void windowOpened(WindowEvent e) { 
} 

@Override 
public void mouseClicked(MouseEvent e) { 
    int x = e.getX() - 8; 
    int y = e.getY() - 30; 
    // System.out.println(y); 
    if (x >= 50 && x <= 143 && y >= 50 && y <= 75) { //if statement for encrypt button bounds 
     log("Button Pressed. Encrypt Screen Opened."); 
     // Frame f = new Frame(); 
     // f.setVisible(true); 
     // f.setSize(100, 100); 
     mode = Modes.Encrypt; 
     new EncryptionSubtask(); 
    } 
    if (x >= 500 && x <= 595 && y >= 50 && y <= 75) { // if statement for decrypt button bounds 
     log("Button Pressed. Decrypt Screen Opened."); 
     mode = Modes.Decrypt; 
    } 
} 

@Override 
public void mouseEntered(MouseEvent e) { 
} 

@Override 
public void mouseExited(MouseEvent e) { 
} 

@Override 
public void mousePressed(MouseEvent e) { 
} 

@Override 
public void mouseReleased(MouseEvent e) { 
} 

@Override 
public void keyPressed(KeyEvent e) { 
    int key = e.getKeyCode(); 
    System.out.println("Key pressed = " + key); 
    if (key == 27) { 
     mode = Modes.Menu; 
    } 
} 

@Override 
public void keyReleased(KeyEvent e) { 
} 

@Override 
public void keyTyped(KeyEvent e) { 
} 

public enum LogLevel { 
    Info, Warn 
} 

private static int width = 300; 
private static int height = width/16 * 9; 
private static int scale = 3; 

public Main() { 
    addWindowListener(this); 
    log("Initialising..."); 
    try { 
     TimeUnit.SECONDS.sleep(1); 
    } catch (InterruptedException e1) { 
     e1.printStackTrace(); 
    } 
    this.start(); 
    log("Setting title..."); 
    try { 
     TimeUnit.SECONDS.sleep(1); 
    } catch (InterruptedException e1) { 
     e1.printStackTrace(); 
    } 
    this.setTitle("LOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOL"); 
    log("Creating backbuffer for window..."); 
    setSize(width * scale, height * scale); 
    backbuffer = new BufferedImage(640 * 3, 480 * 2, BufferedImage.TYPE_INT_RGB); 
    log("Buffering Image, standby..."); 
    try { 
     TimeUnit.SECONDS.sleep(1); 
    } catch (InterruptedException e1) { 
     e1.printStackTrace(); 
    } 
    g2d = backbuffer.createGraphics(); 

    File fileThis = new File(System.getProperty("java.class.path")); 
    File parentFile = fileThis.getAbsoluteFile().getParentFile(); // the 
                    // project 
                    // folder 
    log(parentFile.getAbsolutePath()); 
    File resources = new File(parentFile.toString() + "/resources/"); 
    log(resources.getAbsolutePath()); 
    try { 
     background = ImageIO.read(new File(resources + "/guitar.jpg")); // CHANGE 
                     // THIS 
                     // IMAGE! 
     File tempFile = new File(resources + "/guitar.jpg"); 
     log(tempFile.getAbsolutePath()); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 



    addKeyListener(this); 
    addMouseListener(this); 
} 

@Override 
public void run() { 
    Thread t = Thread.currentThread(); 

    while (t == thread) { 
     try { 
      // log("Running..."); 
      Thread.sleep(20); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
     repaint(); 
    } 
} 

public void start() { 
    thread = new Thread(this); 
    thread.start(); 
} 

public void stop() { 
    try { 
     thread.join(); 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 
} 

public void update(Graphics g) { 
    g2d.setTransform(transform); 
    g2d.setPaint(Color.black); 
    g2d.fillRect(0, 0, getWidth(), getHeight()); 
    switch (mode) { 
    case Menu: 
     g2d.drawImage(background, 0, 0, getWidth(), getHeight(), this); 
     g2d.setPaint(Color.blue); 
     g2d.fillRect(50, 50, 93, 25); 
     g2d.fillRect(500, 50, 95, 25); 
     g2d.setPaint(Color.red); 
     g2d.setFont(new Font("TimesRoman", Font.PLAIN, 30)); 
     g2d.drawString("Encrypt", 50, 70); 
     g2d.drawString("Decrypt", 500, 70); 
     break; 
    case Encrypt: 
     g2d.setPaint(Color.green); 
     g2d.drawString("Encrypt screen", 50, 70); 
     break; 
    case Decrypt: 
     g2d.setPaint(Color.green); 
     g2d.drawString("Decrypt Screen", 50, 70); 
     break; 
    } 

    paint(g); 
} 

public void log(String s) { 
    log(s, 0, 0); 
} 

public void log(String s, int i) { 
    log(s, i, 0); 
} 

public void log(String s, int i, int j) { 
    String logmsg = ""; 
    for (int k = 0; k < i; k++) { 
     logmsg += " "; 
    } 
    if (j == 0) { 
     logmsg = "[Info]" + logmsg; 
    } else { 
     logmsg = "[Warn]" + logmsg; 
    } 
    System.out.println("[" + System.currentTimeMillis() + "][" 
      + Thread.currentThread().getStackTrace()[1].toString() + "]" + logmsg + s); 
} 

public void paint(Graphics g) { 
    g.drawImage(backbuffer, 8, 31, this); 
} 

}

所以，我可以用它来被绘制到我的框架等

Answer 1

好的，你在mouseClicked方法中调用EncryptionSubtask的构造函数，并且你什么都不做。

首先，你需要将其分配给一个变量，就像这样：

EncryptionSubtask veryStrangeTask = new EncryptionSubtask(); 

不是让局部变量passcode作为一类领域是这样的：

public class EncryptionSubtask { 
String passcode; 
... 
} 

现在你可以在您的“其他”类中使用此字段

veryStrangeTask.passcode; 

Answer 2

也许观察者？

您可以创建具有方法的接口来传递您的密码

public interface PasscodeNotify{ 
    public void notifyPasscode(String passcode); 
} 

然后修改EncryptionSubtask构造函数来接受这个类的一个实例，是这样的：

public EncryptionSubtask(PasscodeNotify observer) { 
    ... 
    if(observer != null) 
     observer.notifyPasscode(c1+c2+c3+c4+c5+c6+c7+c8); 
} 

最后你使你的Main类实现另一个接口，我刚刚创建的PasscodeNotify，并实现该方法来检索你的密码。

它是否符合您的要求？

希望它有帮助！