我有一个 slider ，可以创建 RGB 值，然后使用它来创建一个框并填充其颜色。当我初始化程序时，它不会立即绘制正方形。它将绘制正方形并在移动 slider 后开始填充它。
用于绘制矩形并用颜色填充它的方法在构造函数期间被调用，但不执行任何操作，没有错误，只是不绘制正方形。 slider 在状态更改时调用 SAME 方法，然后绘制正方形。这没有任何意义。
我相信其他人在缺乏基础的情况下也可能会遇到这种情况。
这是我的代码，您可以复制粘贴并在 jGrasp 或其他任何程序中运行以了解我的意思。谢谢!
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Colors extends javax.swing.JFrame {
public Colors() {
initComponents();
addSliderListeners();
addSliderLabels();
this.setTitle("Color Mixer");
sliderRed.setValue(150);
sliderGreen.setValue(125);
sliderBlue.setValue(215);
updateImage();
}
private void addSliderListeners(){
sliderRed.addChangeListener(new ChangeListener() {
public void stateChanged(ChangeEvent e) {
updateImage();
}
});
sliderGreen.addChangeListener(new ChangeListener() {
public void stateChanged(ChangeEvent e) {
updateImage();
}
});
sliderBlue.addChangeListener(new ChangeListener() {
public void stateChanged(ChangeEvent e) {
updateImage();
}
});
}
private void updateImage(){
lblRedDec.setText(""+sliderRed.getValue());
lblRedDec.setForeground(new Color(sliderRed.getValue(),0,0));
lblRedHex.setText(Integer.toHexString(sliderRed.getValue()));
lblRedHex.setForeground(lblRedDec.getForeground());
lblGreenDec.setText(""+sliderGreen.getValue());
lblGreenDec.setForeground(new Color(0,sliderGreen.getValue(),0));
lblGreenHex.setText(Integer.toHexString(sliderGreen.getValue()));
lblGreenHex.setForeground(lblGreenDec.getForeground());
lblBlueDec.setText(""+sliderBlue.getValue());
lblBlueHex.setText(Integer.toHexString(sliderBlue.getValue()));
lblBlueDec.setForeground(new Color(0,0,sliderBlue.getValue()));
lblBlueHex.setForeground(lblBlueDec.getForeground());
Graphics2D g2 = (Graphics2D)this.getGraphics();
g2.setColor(new Color(sliderRed.getValue(),sliderGreen.getValue(),sliderBlue.getValue()));
g2.fill(new Rectangle(25,125,250,250));
}
private void addSliderLabels() {
sliderRed.setPaintLabels(true);
sliderGreen.setPaintLabels(true);
sliderBlue.setPaintLabels(true);
}
/**
* 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() {
sliderRed = new javax.swing.JSlider();
lblRed = new javax.swing.JLabel();
lblRedHex = new javax.swing.JLabel();
lblRedDec = new javax.swing.JLabel();
sliderGreen = new javax.swing.JSlider();
lblGreen = new javax.swing.JLabel();
lblGreenHex = new javax.swing.JLabel();
lblGreenDec = new javax.swing.JLabel();
sliderBlue = new javax.swing.JSlider();
lblBlue = new javax.swing.JLabel();
lblBlueHex = new javax.swing.JLabel();
lblBlueDec = new javax.swing.JLabel();
lblTitle = new java.awt.Label();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setResizable(false);
sliderRed.setMajorTickSpacing(15);
sliderRed.setMaximum(255);
sliderRed.setMinorTickSpacing(5);
sliderRed.setOrientation(javax.swing.JSlider.VERTICAL);
sliderRed.setPaintTicks(true);
sliderRed.setValue(212);
sliderRed.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
sliderRed.setName(""); // NOI18N
lblRed.setFont(new java.awt.Font("Tahoma", 1, 11)); // NOI18N
lblRed.setText("Red");
lblRedHex.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
lblRedHex.setText("hex");
lblRedDec.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
lblRedDec.setText("dec");
sliderGreen.setMajorTickSpacing(15);
sliderGreen.setMaximum(255);
sliderGreen.setMinorTickSpacing(5);
sliderGreen.setOrientation(javax.swing.JSlider.VERTICAL);
sliderGreen.setPaintTicks(true);
sliderGreen.setSnapToTicks(true);
sliderGreen.setValue(35);
sliderGreen.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
sliderGreen.setName(""); // NOI18N
lblGreen.setFont(new java.awt.Font("Tahoma", 1, 11)); // NOI18N
lblGreen.setText("Green");
lblGreenHex.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
lblGreenHex.setText("hex");
lblGreenDec.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
lblGreenDec.setText("dec");
sliderBlue.setMajorTickSpacing(15);
sliderBlue.setMaximum(255);
sliderBlue.setMinorTickSpacing(5);
sliderBlue.setOrientation(javax.swing.JSlider.VERTICAL);
sliderBlue.setPaintTicks(true);
sliderBlue.setSnapToTicks(true);
sliderBlue.setValue(218);
sliderBlue.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
sliderBlue.setName(""); // NOI18N
lblBlue.setFont(new java.awt.Font("Tahoma", 1, 11)); // NOI18N
lblBlue.setText("Blue");
lblBlueHex.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
lblBlueHex.setText("hex");
lblBlueDec.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
lblBlueDec.setText("dec");
lblTitle.setFont(new java.awt.Font("Dialog", 0, 36)); // NOI18N
lblTitle.setText("Color Mixer");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap()
.addComponent(lblTitle, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 125, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(layout.createSequentialGroup()
.addGap(27, 27, 27)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(lblRedHex)
.addComponent(lblRed)
.addComponent(lblRedDec))
.addGap(25, 25, 25))
.addComponent(sliderRed, javax.swing.GroupLayout.PREFERRED_SIZE, 71, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(sliderGreen, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 71, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(lblGreenHex)
.addComponent(lblGreen)
.addComponent(lblGreenDec))
.addGap(25, 25, 25)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(sliderBlue, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.PREFERRED_SIZE, 71, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(lblBlueHex)
.addComponent(lblBlue)
.addComponent(lblBlueDec))
.addGap(25, 25, 25))))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap(23, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(layout.createSequentialGroup()
.addComponent(lblBlueDec)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(lblBlueHex)
.addGap(18, 18, 18)
.addComponent(lblBlue)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(sliderBlue, javax.swing.GroupLayout.PREFERRED_SIZE, 285, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addComponent(lblGreenDec)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(lblGreenHex)
.addGap(18, 18, 18)
.addComponent(lblGreen)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(sliderGreen, javax.swing.GroupLayout.PREFERRED_SIZE, 285, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addComponent(lblRedDec)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(lblRedHex)
.addGap(16, 16, 16)
.addComponent(lblRed)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(sliderRed, javax.swing.GroupLayout.PREFERRED_SIZE, 285, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addComponent(lblTitle, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(38, 38, 38))
);
lblTitle.getAccessibleContext().setAccessibleName("");
lblTitle.getAccessibleContext().setAccessibleDescription("");
pack();
}// </editor-fold>
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Colors.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Colors().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JLabel lblBlue;
private javax.swing.JLabel lblBlueDec;
private javax.swing.JLabel lblBlueHex;
private javax.swing.JLabel lblGreen;
private javax.swing.JLabel lblGreenDec;
private javax.swing.JLabel lblGreenHex;
private javax.swing.JLabel lblRed;
private javax.swing.JLabel lblRedDec;
private javax.swing.JLabel lblRedHex;
private java.awt.Label lblTitle;
private javax.swing.JSlider sliderBlue;
private javax.swing.JSlider sliderGreen;
private javax.swing.JSlider sliderRed;
// End of variables declaration
}
最佳答案
颜色方 block 最初不显示的原因是 GroupLayout 导致其所有子组件重新绘制，从而有效地“绘制”了方 block 。
要让您的方 block 显示出来，您可以:
- 制作自定义
JComponent颜色方 block 并添加到GroupLayout中。 - 将所有当前组件提取到新的
JComponent并重写paintComponent方法，以便首先绘制所有GroupLayout组件。此选项允许您不将颜色方 block 添加到GroupLayout中。
代码:
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
updateImage();
}
关于表单加载时 Java GUI 绘制并填充矩形，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13426995/