我一直在尝试将绘图添加到 JForm 中的现有 JPanel 中。该 JForm 是在 Netbeans 中创建的(使用“add jform”选项)。在该表单中,我放置了一个 JPanel。在源代码中我想更改 JPanel,以便出现绘图。我一直在尝试这个,但它不会工作...是否可以这样做(如果是真的,我做错了什么?)...
jPanel3 = new JPanel() {
@Override
public void paintComponent( Graphics g ) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
Line2D line = new Line2D.Double(10, 10, 120, 120);
g2.setColor(Color.blue);
g2.setStroke(new BasicStroke(10));
g2.draw(line);
}
};
问候, 乔佩
(抱歉我的英语不好...我的第一语言不是英语...)
编辑: 一些代码:
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package javatest;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Line2D;
import javax.swing.JPanel;
/**
*
* @author Joppe
*/
public class JavaTest extends javax.swing.JFrame {
/**
* Creates new form JavaTest
*/
public JavaTest() {
initComponents();
}
/**
* 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() {
jPanel3 = new javax.swing.JPanel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jPanel3.addContainerListener(new java.awt.event.ContainerAdapter() {
public void componentAdded(java.awt.event.ContainerEvent evt) {
jPanel3ComponentAdded(evt);
}
});
javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
jPanel3.setLayout(jPanel3Layout);
jPanel3Layout.setHorizontalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 380, Short.MAX_VALUE)
);
jPanel3Layout.setVerticalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 278, Short.MAX_VALUE)
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jPanel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jPanel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addContainerGap())
);
pack();
}// </editor-fold>
private void jPanel3ComponentAdded(java.awt.event.ContainerEvent evt) {
jPanel3 = new JPanel() {
@Override
public void paintComponent( Graphics g ) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
Line2D line = new Line2D.Double(10, 10, 120, 120);
g2.setColor(Color.blue);
g2.setStroke(new BasicStroke(10));
g2.draw(line);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(250,200);
}
};
}
/**
* @param args the command line arguments
*/
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(JavaTest.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(JavaTest.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(JavaTest.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(JavaTest.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 JavaTest().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JPanel jPanel3;
// End of variables declaration
}
最佳答案
当您进行自定义绘画时,您还需要重写面板的 getPreferredSize() 以重新运行自定义绘画的大小,否则大小将被假定为 (0, 0),因此没有任何内容可绘制。您还应该覆盖最小/最大尺寸。
阅读 Swing 教程中关于 Custom Painting 的部分了解更多信息和示例。
如果您需要更多帮助,请发布正确的 SSCCE
来演示问题。
编辑:
jPanel3 = new javax.swing.JPanel();
上面的代码行创建了一个空面板。后来有代码将该面板添加到框架中,但该面板中没有任何内容可显示。
jPanel3.addContainerListener(new java.awt.event.ContainerAdapter() {
public void componentAdded(java.awt.event.ContainerEvent evt) {
jPanel3ComponentAdded(evt);
}
});
不确定这段代码的意义是什么。当您将组件添加到 jPanel3 时,应该触发该事件。我没有看到:
jPanel3.add(....);
代码中的任何位置,因此永远不应该触发此事件。如果此事件确实被触发,则执行的代码为:
jPanel3 = new JPanel() {
@Override
public void paintComponent( Graphics g ) {
...
这段代码没有做任何事情。它所做的只是创建一个组件并更改变量 jPanel3 以引用该组件。但是,该组件不会添加到 GUI 的任何位置,因此您永远不会看到自定义绘画。
您的问题出在 IDE 上。我的建议是忘记 IDE 并学习如何手动创建 GUI。我已经为您提供了有关“自定义绘画”的 Swing 教程的链接,该教程可以执行此操作。与其花时间学习 IDE,不如花时间学习 Java。一旦您了解了 Java 的工作原理,您可能就能更好地理解 IDE。
无论如何,我无法建议您如何使用 IDE,因为我从未使用过 IDE。
关于java - 重新创建一个 Jpanel,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/18803111/