java - GUI 最初未显示(netbeans)

Question

我对 Java 很陌生，对 NetBeans 甚至还比较陌生。我只是不知道如何解决这个问题。

当我运行我的项目时，GUI 最初不显示。应该有一个带有下拉菜单的菜单栏，用于打开和保存文件以及退出程序。窗口底部还应该有三个按钮，可用于显示文件中的数据(在本例中为图像)。但相反，当您运行程序时，窗口是空白的，什么也没有显示。

当我单击左上角"file"位于菜单栏上的位置时，它就会显示出来，并且顶部按钮也会在此时显示。后两个按钮应显示为灰色，并且只有在单击第一个按钮并显示第一张图像后才可单击。

我尝试寻找解决方案，并摆弄 NetBeans 设置，但似乎无法解决此问题。我假设这与一些东西被错误地放置在前景或背景有关，但我不确定。

另外，我发现如果我删除代码中的drawImage位((public void Paint (Graphics g) {g.drawImage(imageToPaint, 50, 70, this);})，那么GUI就会出现，所以我我猜这与某些地方有冲突？!

如果有人能对此有所了解，请提前致谢!

package final_project;

import java.awt.*;
import java.awt.event.*;
import java.awt.image.MemoryImageSource;
import java.util.*;
import javax.swing.*;
import javax.swing.filechooser.FileFilter;
import javax.swing.filechooser.FileNameExtensionFilter;


public abstract class Analyst extends javax.swing.JFrame 
  implements ActionListener {

double heights[][] = new double [300][300];
double grads[][] = new double [300][300];
double tempg[] = new double [8];
double wgrads[][] = new double [300][300];

Image imageToPaint;

public boolean shouldcolourheights = false;

int blue = 1;
int green = 1;
int red = 1;

public Analyst() {
    initComponents();
}

public double [][] convertFromString(String[] stArray){
    double[][] data = new double [300][300];
    int lines = stArray.length;
    for (int i = 0; i<lines; i++){
        StringTokenizer st = new StringTokenizer(stArray[i]," ");
        int j=0;
        while (st.hasMoreTokens()){
            data[i][j]=Double.parseDouble(st.nextToken());
            j++;
        }
    }
    return data;
}


double[] get1DArray (double[][] twoDarray) { 
    double[] tempArray = new double[twoDarray.length * twoDarray[0].length]; 
    for (int i = 0; i < twoDarray.length; i++) {
        for (int j = 0; j < twoDarray[i].length; j++) {
            tempArray[(i * twoDarray[0].length) + j] = twoDarray[i][j];
        }
    }
    return tempArray;
}

public double getMaxGrad (int bound){
    double maxgrad = 0.0;
    for (int k=0; k<bound; k++){
        if (tempg[k]>maxgrad){
            maxgrad=tempg[k];
        }
    }
    return maxgrad;
}


public Image getImage (double [][] array) {
    int arrayW = array[0].length;
    int [] pixels = new int [array.length * arrayW];
    double [] oneDim = get1DArray(array);
    for (int i = 0; i < pixels.length; i++) {
        int value = (int) oneDim[i];
        if (value > 255){
            value = 255;
        }
        if (shouldcolourheights){
            int newi = (int) Math.floor(i/300);
            int newj = (int) i-(newi*300);
            if (grads[newi][newj] < 1.0){
                blue=1; green=1; red=1;
            } else if (grads[newi][newj] <=1.5) {
                blue=0; red=0; green=1;
            } else if (grads[newi][newj] <=3.0) {
                blue=1; red=0; green=0;
            } else {blue=0; red=1; green=0;}
        }
        Color pixel;
        pixel = new Color(value * red, value * green, value * blue, 255);   
        pixels[i] = pixel.getRGB();       
    }
    MemoryImageSource memImage = new MemoryImageSource(arrayW,arrayW,pixels,0,arrayW);
    Panel p = new Panel();
    Image image = p.createImage(memImage);
    return image;
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    fc = new javax.swing.JFileChooser();
    btnHeights = new javax.swing.JButton();
    btnGradients = new javax.swing.JButton();
    btnColourH = new javax.swing.JButton();
    jMenuBar = new javax.swing.JMenuBar();
    jMenu = new javax.swing.JMenu();
    jMenuOpen = new javax.swing.JMenuItem();
    jMenuSave = new javax.swing.JMenuItem();
    jSeparator = new javax.swing.JPopupMenu.Separator();
    jMenuExit = new javax.swing.JMenuItem();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    btnHeights.setText("Heights");
    btnHeights.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnHeightsActionPerformed(evt);
        }
    });

    btnGradients.setText("Gradients");
    btnGradients.setEnabled(false);
    btnGradients.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnGradientsActionPerformed(evt);
        }
    });

    btnColourH.setText("Colour Heights");
    btnColourH.setEnabled(false);
    btnColourH.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnColourHActionPerformed(evt);
        }
    });

    jMenu.setText("File");

    jMenuOpen.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_O, java.awt.event.InputEvent.CTRL_MASK));
    jMenuOpen.setText("Open");
    jMenuOpen.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jMenuOpenActionPerformed(evt);
        }
    });
    jMenu.add(jMenuOpen);

    jMenuSave.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_S, java.awt.event.InputEvent.CTRL_MASK));
    jMenuSave.setText("Save");
    jMenuSave.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jMenuSaveActionPerformed(evt);
        }
    });
    jMenu.add(jMenuSave);
    jMenu.add(jSeparator);

    jMenuExit.setText("Exit");
    jMenuExit.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jMenuExitActionPerformed(evt);
        }
    });
    jMenu.add(jMenuExit);

    jMenuBar.add(jMenu);

    setJMenuBar(jMenuBar);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(39, 39, 39)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                .addComponent(btnColourH, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(btnGradients, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(btnHeights, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
            .addContainerGap(258, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addContainerGap(381, Short.MAX_VALUE)
            .addComponent(btnHeights)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(btnGradients)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(btnColourH)
            .addGap(27, 27, 27))
    );

    pack();
}// </editor-fold>                        

private void jMenuOpenActionPerformed(java.awt.event.ActionEvent evt) {                                          
    FileFilter ft = new FileNameExtensionFilter("Text Files", "txt");
    fc.addChoosableFileFilter(ft);
    int returnVal = fc.showOpenDialog(this);
    if (returnVal==javax.swing.JFileChooser.APPROVE_OPTION) {
        java.io.File file = fc.getSelectedFile();
        String file_name = file.toString();
        try {
            ReadFile file_read = new ReadFile(file_name);
            String [] arraylines = file_read.OpenFile();
            heights = convertFromString(arraylines);
            }
        catch (java.io.IOException e) {
           JOptionPane.showMessageDialog(Analyst.this, "File does not exist");
            }
    }
}                                         

private void jMenuSaveActionPerformed(java.awt.event.ActionEvent evt) {                                          
    String tempStr = "";
    FileFilter ft = new FileNameExtensionFilter("Text Files", "txt");
    fc.addChoosableFileFilter(ft);
    int returnVal = fc.showSaveDialog(this);
    if (returnVal==javax.swing.JFileChooser.APPROVE_OPTION) {
        java.io.File saved_file = fc.getSelectedFile();
        String file_name = saved_file.toString();
        try {
            WriteFile dataOut = new WriteFile(file_name, true);
            for (int i=0; i<grads.length; i++) {
                for (int j=0; j<grads[i].length; j++){
                    double rgrad = Math.floor(grads[i][j] * 10) / 10;
                    tempStr = tempStr + String.valueOf(rgrad) +" ";
                }
                dataOut.writeToFile(tempStr);
                tempStr = "";
            }
        }
        catch (java.io.IOException e) {
           JOptionPane.showMessageDialog(Analyst.this, "File not written");
            }
    }
    repaint();
}                                         

private void jMenuExitActionPerformed(java.awt.event.ActionEvent evt) {                                          
    System.exit(0);
}                                         


private void btnHeightsActionPerformed(java.awt.event.ActionEvent evt) {                                           
    shouldcolourheights=false;
    red=1; blue=1; green=1;
    imageToPaint = getImage(heights);
    repaint();
    btnGradients.setEnabled(true);
}                                          

private void btnGradientsActionPerformed(java.awt.event.ActionEvent evt) {                                             
    double root2 = Math.sqrt(2.0);
    double scaling = 1.0;                  //cells of 1m assumed
    double weighting = 40.0;               //to give more defined image
    //The 8 neighbour cells
    for (int i=1; i<299; i++) {
        for (int j=1; j<299; j++){
          tempg[0] = Math.abs(heights[i-1][j-1]-heights[i][j])/root2;
          tempg[1] = Math.abs(heights[i-1][j+1]-heights[i][j])/root2;
          tempg[2] = Math.abs(heights[i+1][j-1]-heights[i][j])/root2;
          tempg[3] = Math.abs(heights[i+1][j+1]-heights[i][j])/root2;
          tempg[4] = Math.abs(heights[i][j-1]-heights[i][j]);
          tempg[5] = Math.abs(heights[i-1][j]-heights[i][j]);
          tempg[6] = Math.abs(heights[i][j+1]-heights[i][j]);
          tempg[7] = Math.abs(heights[i+1][j]-heights[i][j]);
          grads[i][j] = getMaxGrad(8)/scaling;
        }
    }
    //The 5 neighbour cells
    int i=0;
    for (int j=1; j<299; j++) {

        tempg[0] = Math.abs(heights[i][j-1]-heights[i][j]);
        tempg[1] = Math.abs(heights[i+1][j-1]-heights[i][j])/root2;
        tempg[2] = Math.abs(heights[i+1][j]-heights[i][j]);
        tempg[3] = Math.abs(heights[i+1][j+1]-heights[i][j])/root2;
        tempg[4] = Math.abs(heights[i][j+1]-heights[i][j]);                   
        grads[i][j] = getMaxGrad(5)/scaling;     
    } 
    i=299;
    for (int j=1; j<299; j++){

        tempg[0] = Math.abs(heights[i][j-1]-heights[i][j]);
        tempg[1] = Math.abs(heights[i-1][j-1]-heights[i][j])/root2;
        tempg[2] = Math.abs(heights[i-1][j]-heights[i][j]);
        tempg[3] = Math.abs(heights[i-1][j+1]-heights[i][j])/root2;
        tempg[4] = Math.abs(heights[i][j+1]-heights[i][j]);
        grads[i][j] = getMaxGrad(5)/scaling;
    }
    int j=0;
    for (i=1; i<299; i++){
        tempg[0] = Math.abs(heights[i-1][j]-heights[i][j]);
        tempg[1] = Math.abs(heights[i-1][j+1]-heights[i][j])/root2;
        tempg[2] = Math.abs(heights[i][j+1]-heights[i][j]);
        tempg[3] = Math.abs(heights[i+1][j+1]-heights[i][j])/root2;
        tempg[4] = Math.abs(heights[i+1][j]-heights[i][j]);
        grads[i][j] = getMaxGrad(5)/scaling;
    }   
    j=299;
    for (i=1; i<299; i++){
        tempg[0] = Math.abs(heights[i+1][j]-heights[i][j]);
        tempg[1] = Math.abs(heights[i+1][j-1]-heights[i][j])/root2;
        tempg[2] = Math.abs(heights[i][j-1]-heights[i][j]);
        tempg[3] = Math.abs(heights[i-1][j-1]-heights[i][j])/root2;
        tempg[4] = Math.abs(heights[i-1][j]-heights[i][j]);
        grads[i][j] = getMaxGrad(5)/scaling;
    }   
    //The 3 neighbour cells
    i=0; j=0;
    tempg[0] = Math.abs(heights[i+1][j]-heights[i][j]);
    tempg[1] = Math.abs(heights[i+1][j+1]-heights[i][j])/root2;
    tempg[2] = Math.abs(heights[i][j+1]-heights[i][j]);

    grads[i][j] = getMaxGrad(3)/scaling;

    i=299; j=0;
    tempg[0] = Math.abs(heights[i-1][j]-heights[i][j]);
    tempg[1] = Math.abs(heights[i-1][j+1]-heights[i][j])/root2;
    tempg[2] = Math.abs(heights[i][j+1]-heights[i][j]);

    grads[i][j] = getMaxGrad(3)/scaling;

    i=0; j=299;
    tempg[0] = Math.abs(heights[i][j-1]-heights[i][j]);
    tempg[1] = Math.abs(heights[i+1][j-1]-heights[i][j])/root2;
    tempg[2] = Math.abs(heights[i+1][j]-heights[i][j]);

    grads[i][j] = getMaxGrad(3)/scaling;

    i=299; j=299;
    tempg[0] = Math.abs(heights[i][j-1]-heights[i][j]);
    tempg[1] = Math.abs(heights[i-1][j-1]-heights[i][j])/root2;
    tempg[2] = Math.abs(heights[i-1][j]-heights[i][j]);

    grads[i][j] = getMaxGrad(3)/scaling;
    //grads holds the actual 'D8' gradients and is to be written to
    //a file.  In order to display greyscale image the values need to be
    //weighted up (grads is left unchanged).
    //
    for (i=0; i<300; i++) {
        for (j=0; j<300; j++){
            wgrads[i][j] = grads[i][j] * weighting;
        }     
    }
    shouldcolourheights=false;
    red=1; blue=1; green=1;
    imageToPaint = getImage(wgrads);

    repaint();
    jMenuSave.setEnabled(true);
    btnColourH.setEnabled(true);
}                                            

public void paint (Graphics g) {
        g.drawImage(imageToPaint, 50, 70, this);
}

 /**
 * Redraws the height image with colour to represent the gradients.
 * @param evt 
 */
private void btnColourHActionPerformed(java.awt.event.ActionEvent evt) {                                           
    shouldcolourheights=true;
    imageToPaint = getImage(heights);
    repaint();
}                                          



/**
 * @param args the command line arguments
 */
 public static void main(String args[]) {
    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new Analyst() {

                public void actionPerformed(ActionEvent e) {
                    throw new UnsupportedOperationException("Not supported yet.");
                } 
            } .setVisible(true);
        } 
    });
}

// Variables declaration - do not modify                     
private javax.swing.JButton btnColourH;
private javax.swing.JButton btnGradients;
private javax.swing.JButton btnHeights;
private javax.swing.JFileChooser fc;
private javax.swing.JMenu jMenu;
private javax.swing.JMenuBar jMenuBar;
private javax.swing.JMenuItem jMenuExit;
private javax.swing.JMenuItem jMenuOpen;
private javax.swing.JMenuItem jMenuSave;
private javax.swing.JPopupMenu.Separator jSeparator;
// End of variables declaration                   
}

Answer 1

添加super.paint(g)。

@Override
public void paint(Graphics g) {
    super.paint(g);
    g.drawImage(imageToPaint, 50, 70, this);
}

您还可以使用System.arraycopy来加快复制速度。

double[] get1DArray(double[][] twoDarray) {
    double[] tempArray = new double[twoDarray.length * twoDarray[0].length];
    int jdim = twoDarray[0].length;
    for (int i = 0; i < twoDarray.length; i++) {
        System.arraycopy(twoDarray[i], 0, tempArray, i * jdim, jdim);
    }
    return tempArray;
}