繪畫畫布和System.out.println（）不起作用

Question

我有JFrame帶有一個開始按鈕，它會觸發一個Julia Set的計算。 點擊啓動按鈕時執行的代碼如下：

public void actionPerformed(ActionEvent aActionEvent) 
{ 
    String strCmd = aActionEvent.getActionCommand(); 

    if (strCmd.equals("Start")) 
    { 
     m_cCanvas.init(); 
     m_cSMsg = "c = " + Double.toString(m_dReal) + " + " + "j*" + Double.toString(m_dImag); 
     m_bRunning = true; 
     this.handleCalculation(); 
    } 
    else if (aActionEvent.getSource() == m_cTReal) 

它用來做工精細，除了應用程序無法再被關閉。所以，我想在一個單獨的方法使用m_bRunning使actionPerformed()不會被阻止所有的時間，看看是否要幫忙的，則在該方法stop()設置m_bRunning = false時關閉該窗口被稱爲：

public void run() 
{ 
    if(m_bRunning) 
    { 
     this.handleCalculation(); 
    } 
} 

方法run()在while(true)循環中從主類調用。

不幸的是，這兩個問題都沒有解決問題，也沒有任何輸出到畫布或任何帶有System.out.println()的調試跟蹤。任何人都可以在這個方向上指出我的正確方向嗎？

編輯：

這裏是整個文件：

// cMain.java 
package juliaSet; 

import java.awt.Toolkit; 
import java.awt.event.ActionEvent; 
import java.awt.Dimension; 

public class cMain { 

    public static void main(String[] args) 
    { 
     int windowWidth = 1000;//(int)screenSize.getWidth() - 200; 
     int windowHeight = 800;//(int)screenSize.getHeight() - 50; 
     int plotWidth = 400;//(int)screenSize.getWidth() - 600; 
     int plotHeight = 400;//(int)screenSize.getHeight() - 150; 

     JuliaSet cJuliaSet = new JuliaSet("Julia Set", windowWidth, windowHeight, plotWidth, plotHeight);  
     cJuliaSet.setVisible(true);  
     while(true) 
     { 
      cJuliaSet.run(); 
     } 
    } 

} 


// JuliaSet.java 
package juliaSet; 

import java.awt.*; 
import java.awt.event.*; 
import java.awt.image.*; 
import javax.swing.*; 
import java.util.Random; 
import java.io.*; 
import java.lang.ref.*; 

public class JuliaSet extends JFrame implements ActionListener 
{ 
    private JButton m_cBStart; 
    private JTextField m_cTReal; 
    private JTextField m_cTImag; 
    private JTextField m_cTDivergThresh; 
    private JLabel m_cLReal; 
    private JLabel m_cLImag; 
    private JLabel m_cLDivergThresh; 
    private int m_iDivergThresh = 10; 
    private String m_cMsgDivThresh = "Divergence threshold = " + m_iDivergThresh; 
    private JuliaCanvas m_cCanvas; 
    private int m_iPlotWidth; // number of cells 
    private int m_iPlotHeight; // number of cells 
    private Boolean m_bRunning = false; 
    private double m_dReal = 0.3; 
    private double m_dImag = -0.5; 
    private String m_cSMsg = "c = " + Double.toString(m_dReal) + " + " + "j*" + Double.toString(m_dImag); 
    private String m_cMsgIter = "x = 0, y = 0"; 
    private Complex m_cCoordPlane[][]; 
    private double m_dAbsSqValues[][]; 
    private int m_iIterations[][]; 
    private Complex m_cSummand; 
    private BufferedImage m_cBackGroundImage = null; 
    private FileWriter m_cFileWriter; 
    private BufferedWriter m_cBufferedWriter; 
    private String m_sFileName = "log.txt"; 
    private Boolean m_bWriteLog = false; 

    private static final double PLOTMAX = 2.0; // we'll have symmetric axes 
               // ((0,0) at the centre of the 
               // plot 
    private static final int MAXITER = 0xff; 

    JuliaSet(String aTitle, int aFrameWidth, int aFrameHeight, int aPlotWidth, int aPlotHeight) 
    { 
     super(aTitle); 
     this.setSize(aFrameWidth, aFrameHeight); 
     m_iPlotWidth = aPlotWidth; 
     m_iPlotHeight = aPlotHeight; 
     m_cSummand = new Complex(m_dReal, m_dImag); 

     m_cBackGroundImage = new BufferedImage(aFrameWidth, aFrameHeight, BufferedImage.TYPE_INT_RGB); 

     this.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE); 
     this.addWindowListener(new WindowAdapter() { 
      public void windowClosing(WindowEvent e) { 
       stop(); 
       super.windowClosing(e); 
       System.exit(0); 
      } 
     }); 

     GridBagLayout cLayout = new GridBagLayout(); 
     GridBagConstraints cConstraints = new GridBagConstraints(); 

     this.setLayout(cLayout); 
     m_cCanvas = new JuliaCanvas(m_iPlotWidth, m_iPlotHeight); 
     m_cCanvas.setSize(m_iPlotWidth, m_iPlotHeight); 

     m_cBStart = new JButton("Start"); 
     m_cBStart.addActionListener(this); 
     m_cTReal = new JTextField(5); 
     m_cTReal.addActionListener(this); 
     m_cTImag = new JTextField(5); 
     m_cTImag.addActionListener(this); 
     m_cTDivergThresh = new JTextField(5); 
     m_cTDivergThresh.addActionListener(this); 
     m_cLReal = new JLabel("Re(c):"); 
     m_cLImag = new JLabel("Im(c):"); 
     m_cLDivergThresh = new JLabel("Divergence Threshold:"); 

     cConstraints.insets.top = 3; 
     cConstraints.insets.bottom = 3; 
     cConstraints.insets.right = 3; 
     cConstraints.insets.left = 3; 

     // cCanvas 
     cConstraints.gridx = 0; 
     cConstraints.gridy = 0; 
     cLayout.setConstraints(m_cCanvas, cConstraints); 
     this.add(m_cCanvas); 

     // m_cLReal 
     cConstraints.gridx = 0; 
     cConstraints.gridy = 1; 
     cLayout.setConstraints(m_cLReal, cConstraints); 
     this.add(m_cLReal); 

     // m_cTReal 
     cConstraints.gridx = 1; 
     cConstraints.gridy = 1; 
     cLayout.setConstraints(m_cTReal, cConstraints); 
     this.add(m_cTReal); 

     // m_cLImag 
     cConstraints.gridx = 0; 
     cConstraints.gridy = 2; 
     cLayout.setConstraints(m_cLImag, cConstraints); 
     this.add(m_cLImag); 

     // m_cTImag 
     cConstraints.gridx = 1; 
     cConstraints.gridy = 2; 
     cLayout.setConstraints(m_cTImag, cConstraints); 
     this.add(m_cTImag); 

     // m_cLDivergThresh 
     cConstraints.gridx = 0; 
     cConstraints.gridy = 3; 
     cLayout.setConstraints(m_cLDivergThresh, cConstraints); 
     this.add(m_cLDivergThresh); 

     // m_cTDivergThresh 
     cConstraints.gridx = 1; 
     cConstraints.gridy = 3; 
     cLayout.setConstraints(m_cTDivergThresh, cConstraints); 
     this.add(m_cTDivergThresh); 

     // m_cBStart 
     cConstraints.gridx = 0; 
     cConstraints.gridy = 4; 
     cLayout.setConstraints(m_cBStart, cConstraints); 
     this.add(m_cBStart); 
     if (m_bWriteLog) 
     { 
      try 
      { 
       m_cFileWriter = new FileWriter(m_sFileName, false); 
       m_cBufferedWriter = new BufferedWriter(m_cFileWriter); 
      } catch (IOException ex) { 
       System.out.println("Error opening file '" + m_sFileName + "'"); 
      } 
     } 

     this.repaint(); 

     this.transformCoordinates(); 
    } 

    public synchronized void stop() 
    { 
     if (m_bRunning) 
     { 
      m_bRunning = false; 
      boolean bRetry = true; 
     } 
     if (m_bWriteLog) 
     { 
      try { 
       m_cBufferedWriter.close(); 
       m_cFileWriter.close(); 
      } catch (IOException ex) { 
       System.out.println("Error closing file '" + m_sFileName + "'"); 
      } 
     } 
    } 
    public void collectGarbage() 
    { 
     Object cObj = new Object(); 
     WeakReference ref = new WeakReference<Object>(cObj); 
     cObj = null; 
     while(ref.get() != null) { 
      System.gc(); 
     } 
    } 

    public void setSummand(Complex aSummand) 
    { 
     m_cSummand.setIm(aSummand.getIm()); 
     m_dImag = aSummand.getIm(); 
     m_cSummand.setRe(aSummand.getRe()); 
     m_dReal = aSummand.getRe(); 
     m_cSMsg = "c = " + Double.toString(m_dReal) + " + " + "j*" + Double.toString(m_dImag); 
    } 

    public void paint(Graphics aGraphics) 
    { 
     Graphics cScreenGraphics = aGraphics; 
     // render on background image 
     aGraphics = m_cBackGroundImage.getGraphics(); 

     this.paintComponents(aGraphics); 
     // drawString() calls are debug code only.... 
     aGraphics.setColor(Color.BLACK); 
     aGraphics.drawString(m_cSMsg, 10, 450); 
     aGraphics.drawString(m_cMsgIter, 10, 465); 
     aGraphics.drawString(m_cMsgDivThresh, 10, 480); 

     // rendering is done, draw background image to on screen graphics 
     cScreenGraphics.drawImage(m_cBackGroundImage, 0, 0, null); 
    } 

    public void actionPerformed(ActionEvent aActionEvent) 
    { 
     String strCmd = aActionEvent.getActionCommand(); 

     if (strCmd.equals("Start")) 
     { 
      m_cCanvas.init(); 
      m_cSMsg = "c = " + Double.toString(m_dReal) + " + " + "j*" + Double.toString(m_dImag); 
      m_bRunning = true; 
     } 
     else if (aActionEvent.getSource() == m_cTReal) 
     { 
      m_dReal = Double.parseDouble(m_cTReal.getText()); 
      m_cSMsg = "c = " + Double.toString(m_dReal) + " + " + "j*" + Double.toString(m_dImag); 
      m_cSummand.setRe(m_dReal); 
     } 
     else if (aActionEvent.getSource() == m_cTImag) 
     { 
      m_dImag = Double.parseDouble(m_cTImag.getText()); 
      m_cSMsg = "c = " + Double.toString(m_dReal) + " + " + "j*" + Double.toString(m_dImag); 
      m_cSummand.setIm(m_dImag); 
     } 
     else if (aActionEvent.getSource() == m_cTDivergThresh) 
     { 
      m_iDivergThresh = Integer.parseInt(m_cTDivergThresh.getText()); 
      m_cMsgDivThresh = "Divergence threshold = " + m_iDivergThresh; 
     } 

     this.update(this.getGraphics()); 
    } 

    public void transformCoordinates() 
    { 
     double dCanvasHeight = (double) m_cCanvas.getHeight(); 
     double dCanvasWidth = (double) m_cCanvas.getWidth(); 
     // init matrix with same amount of elements as pixels in canvas 
     m_cCoordPlane = new Complex[(int) dCanvasHeight][(int) dCanvasWidth]; 
     double iPlotRange = 2 * PLOTMAX; 

     for (int i = 0; i < dCanvasHeight; i++) 
     { 
      for (int j = 0; j < dCanvasWidth; j++) 
      { 

       m_cCoordPlane[i][j] = new Complex((i - (dCanvasWidth/2)) * iPlotRange/dCanvasWidth, 
         (j - (dCanvasHeight/2)) * iPlotRange/dCanvasHeight); 
      } 
     } 

    } 

    public void calcAbsSqValues() 
    { 
     int iCanvasHeight = m_cCanvas.getHeight(); 
     int iCanvasWidth = m_cCanvas.getWidth(); 
     // init matrix with same amount of elements as pixels in canvas 
     m_dAbsSqValues = new double[iCanvasHeight][iCanvasWidth]; 
     m_iIterations = new int[iCanvasHeight][iCanvasWidth]; 
     Complex cSum = new Complex(); 

     if (m_bWriteLog) { 
      try 
      { 
       m_cBufferedWriter.write("m_iIterations[][] ="); 
       m_cBufferedWriter.newLine(); 
      } 
      catch (IOException ex) 
      { 
       System.out.println("Error opening file '" + m_sFileName + "'"); 
      } 
     } 

     for (int i = 0; i < iCanvasHeight; i++) 
     { 
      for (int j = 0; j < iCanvasWidth; j++) 
      { 
       cSum.setRe(m_cCoordPlane[i][j].getRe()); 
       cSum.setIm(m_cCoordPlane[i][j].getIm()); 
       m_iIterations[i][j] = 0; 
       do 
       { 
        m_iIterations[i][j]++; 
        cSum.square(); 
        cSum.add(m_cSummand); 
        m_dAbsSqValues[i][j] = cSum.getAbsSq(); 
       } while ((m_iIterations[i][j] < MAXITER) && (m_dAbsSqValues[i][j] < m_iDivergThresh)); 
       this.calcColour(i, j, m_iIterations[i][j]); 
       m_cMsgIter = "x = " + i + " , y = " + j; 

       if(m_bWriteLog) 
       { 
        System.out.println(m_cMsgIter); 
        System.out.flush(); 
       } 

       if (m_bWriteLog) { 
        try 
        { 
         m_cBufferedWriter.write(Integer.toString(m_iIterations[i][j])); 
         m_cBufferedWriter.write(" "); 
        } 
        catch (IOException ex) { 
         System.out.println("Error writing to file '" + m_sFileName + "'"); 
        } 
       } 
      } 
      if (m_bWriteLog) { 
       try 
       { 
        m_cBufferedWriter.newLine(); 
       } 
       catch (IOException ex) { 
        System.out.println("Error writing to file '" + m_sFileName + "'"); 
       } 
      } 
     } 
     m_dAbsSqValues = null; 
     m_iIterations = null; 
     cSum = null; 
    } 

    private void calcColour(int i, int j, int aIterations) 
    { 
     Color cColour = Color.getHSBColor((int) Math.pow(aIterations, 4), 0xff, 
       0xff * ((aIterations < MAXITER) ? 1 : 0)); 
     m_cCanvas.setPixelColour(i, j, cColour); 
     cColour = null; 
    } 

    private void handleCalculation() 
    { 
     Complex cSummand = new Complex(); 

     for(int i = -800; i <= 800; i++) 
     { 
      for(int j = -800; j <= 800; j++) 
      { 
       cSummand.setRe(((double)i)/1000.0); 
       cSummand.setIm(((double)j)/1000.0); 
       this.setSummand(cSummand); 
       this.calcAbsSqValues(); 
       this.getCanvas().paint(m_cCanvas.getGraphics()); 
       this.paint(this.getGraphics()); 
      } 
     } 
     cSummand = null; 
     this.collectGarbage(); 
     System.gc(); 
     System.runFinalization(); 
    } 

    public boolean isRunning() 
    { 
     return m_bRunning; 
    } 

    public void setRunning(boolean aRunning) 
    { 
     m_bRunning = aRunning; 
    } 

    public Canvas getCanvas() 
    { 
     return m_cCanvas; 
    } 

    public void run() 
    { 
     if(m_bRunning) 
     { 
      this.handleCalculation(); 
     } 
    } 
} 

class JuliaCanvas extends Canvas 
{ 
    private int m_iWidth; 
    private int m_iHeight; 
    private Random m_cRnd; 
    private BufferedImage m_cBackGroundImage = null; 
    private int m_iRed[][]; 
    private int m_iGreen[][]; 
    private int m_iBlue[][]; 

    JuliaCanvas(int aWidth, int aHeight) 
    { 
     m_iWidth = aWidth; 
     m_iHeight = aHeight; 
     m_cRnd = new Random(); 

     m_cRnd.setSeed(m_cRnd.nextLong()); 

     m_cBackGroundImage = new BufferedImage(m_iWidth, m_iHeight, BufferedImage.TYPE_INT_RGB); 

     m_iRed = new int[m_iHeight][m_iWidth]; 
     m_iGreen = new int[m_iHeight][m_iWidth]; 
     m_iBlue = new int[m_iHeight][m_iWidth]; 
    } 

    public void init() { 

    } 

    public void setPixelColour(int i, int j, Color aColour) 
    { 
     m_iRed[i][j] = aColour.getRed(); 
     m_iGreen[i][j] = aColour.getGreen(); 
     m_iBlue[i][j] = aColour.getBlue(); 
    } 

    private int getRandomInt(double aProbability) 
    { 
     return (m_cRnd.nextDouble() < aProbability) ? 1 : 0; 
    } 

    @Override 
    public void paint(Graphics aGraphics) 
    { 
     // store on screen graphics 
     Graphics cScreenGraphics = aGraphics; 
     // render on background image 
     aGraphics = m_cBackGroundImage.getGraphics(); 


     for (int i = 0; i < m_iWidth; i++) 
     { 
      for (int j = 0; j < m_iHeight; j++) 
      { 
       Color cColor = new Color(m_iRed[i][j], m_iGreen[i][j], m_iBlue[i][j]); 
       aGraphics.setColor(cColor); 
       aGraphics.drawRect(i, j, 0, 0); 
       cColor = null; 
      } 
     } 
     // rendering is done, draw background image to on screen graphics 
     cScreenGraphics.drawImage(m_cBackGroundImage, 1, 1, null); 
    } 

    @Override 
    public void update(Graphics aGraphics) 
    { 
     paint(aGraphics); 
    } 
} 

class Complex { 
    private double m_dRe; 
    private double m_dIm; 

    public Complex() 
    { 
     m_dRe = 0; 
     m_dIm = 0; 
    } 

    public Complex(double aRe, double aIm) 
    { 
     m_dRe = aRe; 
     m_dIm = aIm; 
    } 

    public Complex(Complex aComplex) 
    { 
     m_dRe = aComplex.m_dRe; 
     m_dIm = aComplex.m_dIm; 
    } 

    public double getRe() { 
     return m_dRe; 
    } 

    public void setRe(double adRe) 
    { 
     m_dRe = adRe; 
    } 

    public double getIm() { 
     return m_dIm; 
    } 

    public void setIm(double adIm) 
    { 
     m_dIm = adIm; 
    } 

    public void add(Complex acComplex) 
    { 
     m_dRe += acComplex.getRe(); 
     m_dIm += acComplex.getIm(); 
    } 

    public void square() 
    { 
     double m_dReSave = m_dRe; 
     m_dRe = (m_dRe * m_dRe) - (m_dIm * m_dIm); 
     m_dIm = 2 * m_dReSave * m_dIm; 
    } 

    public double getAbsSq() 
    { 
     return ((m_dRe * m_dRe) + (m_dIm * m_dIm)); 
    } 
} 

Answer 1

第一;

無盡的循環不是一個正確的方法來做到這一點。這部分是循環，並採取CPU和從不給畫布刷新屏幕。如果您添加下面的代碼，您的代碼將按預期運行。但這不是合適的解決方案。

cMain.java：

while (true) { 
    cJuliaSet.run(); 
    try { 
     Thread.sleep(1000); 
    } catch (InterruptedException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
} 

二：你可以調用run方法時，啓動按鈕點擊。但是你應該在run方法中創建一個線程來不凍結屏幕。

public static void main(String[] args) { 
      int windowWidth = 1000;// (int)screenSize.getWidth() - 200; 
      int windowHeight = 800;// (int)screenSize.getHeight() - 50; 
      int plotWidth = 400;// (int)screenSize.getWidth() - 600; 
      int plotHeight = 400;// (int)screenSize.getHeight() - 150; 

      JuliaSet cJuliaSet = new JuliaSet("Julia Set", windowWidth, windowHeight, plotWidth, plotHeight); 
      cJuliaSet.setVisible(true); 
      //While loop removed 
     } 

的actionPerformed：

if (strCmd.equals("Start")) { 
      m_cCanvas.init(); 
      m_cSMsg = "c = " + Double.toString(m_dReal) + " + " + "j*" + Double.toString(m_dImag); 
      m_bRunning = true; 
      this.run(); // added call run method. 
     } else if (aActionEvent.getSource() == m_cTReal) { 

運行方法：

public void run() 
    { 
     if(m_bRunning) 
     { 
      new Thread(){ //Thread to release screen 
       @Override 
       public void run() { 
        JuliaSet.this.handleCalculation(); 
       } 
      }.start(); //also thread must be started 
     } 
    } 

如所述通過@RubioRic，SwingUtilities.invokeLater方法也是溶液的一部分。但是你需要檢查你的整個代碼，你應該學習線程。

Answer 2

我引用來自@MadProgrammer（包括鏈接）

「Swing是單線程的，沒有什麼可以做，以改變這種狀況，所有事件都發布到事件隊列和事件處理的最新評論調度線程，請參閱Concurrency in Swing以獲取更多詳細信息，並在至少一個可能的解決方案中查看Worker Threads and SwingWorker「

代碼中只有一個線程。該線程忙於計算，無法響應位於GUI中的事件。您必須在另一個線程中分開計算，以定期更新窗口中顯示的數量。更多關於這個鏈接的信息，由@MadProgrammer提供，我堅持。

更新：正如指出的@Yusuf，開展JFrame的正確方法是

 SwingUtilities.invokeLater(new Runnable() { 
     @Override 
     public void run() { 
      new JuliaSet("Julia Set", windowWidth, windowHeight, plotWidth, plotHeight); 
     } 
     }); 

設置在框架結構上可見，並且按下開始按鈕時開始計算。