我正在使用Netbeans GUI构建器，但现在有点混乱。如何将图像添加到面板？我认为我做得对，但它没有出现。我认为它应该在init（）方法中，但netbeans不允许我改变代码的那一部分。这是我为图片添加的代码：
//these four lines I added to add the image
imageIcon = new ImageIcon("login_icon.png");
image = new JLabel(imageIcon);
image.setToolTipText("SGS Security");
topPanel.add(image);
我的班级从这里开始：
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
/*
* Login.java
*
* Created on Oct 27, 2009, 8:34:15 PM
*/
package sgs;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
public class Login extends javax.swing.JFrame {
JLabel image;
ImageIcon imageIcon;
/** Creates new form Login */
public Login() {
initComponents();
//these four lines I added to add the image
imageIcon = new ImageIcon("login_icon.png");
image = new JLabel(imageIcon);
image.setToolTipText("SGS Security");
topPanel.add(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() {
topPanel = new javax.swing.JPanel();
userLabel = new javax.swing.JLabel();
passwordLabel = new javax.swing.JLabel();
connectLabel = new javax.swing.JLabel();
forgotPassLabel = new javax.swing.JLabel();
forgotPassCheckBox = new javax.swing.JCheckBox();
cancelButton = new javax.swing.JButton();
okButton = new javax.swing.JButton();
passwordTextField = new javax.swing.JTextField();
userTextField = new javax.swing.JTextField();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setBackground(new java.awt.Color(216, 156, 60));
topPanel.setBackground(new java.awt.Color(28, 90, 198));
javax.swing.GroupLayout topPanelLayout = new javax.swing.GroupLayout(topPanel);
topPanel.setLayout(topPanelLayout);
topPanelLayout.setHorizontalGroup(
topPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 406, Short.MAX_VALUE)
);
topPanelLayout.setVerticalGroup(
topPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 71, Short.MAX_VALUE)
);
userLabel.setText("User name:");
passwordLabel.setText("Password:");
connectLabel.setText("Connect to SGS");
forgotPassLabel.setText("Forgot password");
forgotPassCheckBox.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
forgotPassCheckBoxActionPerformed(evt);
}
});
cancelButton.setText("Cancel");
okButton.setText("OK");
okButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
okButtonActionPerformed(evt);
}
});
userTextField.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
userTextFieldActionPerformed(evt);
}
});
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()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(connectLabel)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(passwordLabel)
.addComponent(userLabel)))
.addGap(30, 30, 30)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(userTextField)
.addComponent(passwordTextField)
.addGroup(layout.createSequentialGroup()
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(forgotPassCheckBox)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(forgotPassLabel))
.addGroup(layout.createSequentialGroup()
.addGap(32, 32, 32)
.addComponent(okButton, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(28, 28, 28)
.addComponent(cancelButton, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addContainerGap())
.addComponent(topPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(topPanel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(27, 27, 27)
.addComponent(connectLabel)
.addGap(34, 34, 34)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(userLabel)
.addComponent(userTextField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(passwordLabel)
.addComponent(passwordTextField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(forgotPassLabel)
.addComponent(forgotPassCheckBox))
.addGap(23, 23, 23)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(okButton, javax.swing.GroupLayout.PREFERRED_SIZE, 31, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(cancelButton, javax.swing.GroupLayout.DEFAULT_SIZE, 31, Short.MAX_VALUE))
.addContainerGap())
);
pack();
}// </editor-fold>
private void forgotPassCheckBoxActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void userTextFieldActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void okButtonActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Login().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton cancelButton;
private javax.swing.JLabel connectLabel;
private javax.swing.JCheckBox forgotPassCheckBox;
private javax.swing.JLabel forgotPassLabel;
private javax.swing.JButton okButton;
private javax.swing.JLabel passwordLabel;
private javax.swing.JTextField passwordTextField;
private javax.swing.JPanel topPanel;
private javax.swing.JLabel userLabel;
private javax.swing.JTextField userTextField;
// End of variables declaration
}
答案 0 :(得分：1)
抛弃GUI构建器并学习如何自己创建GUI。这样你就可以花时间学习Java而不是学习IDE。可能有一些GroupLayout属性没有正确设置，因为GroupLayout被设计为IDE而不是人类使用我不知道问题可能是什么。
另一种可能性是IDE无法找到您的图像。您是否添加了System.out.println以显示图像并确保其不为空。
我建议您阅读How to Use Icons上Swing教程中的部分，了解一个可以下载并测试它是否有效的工作示例。只需将教程中的图标替换为图标即可确保找到它们。
编辑：
在第二次查看代码后，我相信我的原始建议是正确的。您尝试使用一行代码将标签添加到面板：
topPanel.add(image);
查看IDE生成的代码。 add语句并不那么简单。如果您想在事后手动添加组件，那么您需要阅读“如何使用组布局”教程中的部分来理解所使用的各种约束和方法。
或者您需要弄清楚如何在IDE中执行此操作。这就是为什么我更喜欢自己做的方法。然后你负责代码，而不是IDE。
答案 1 :(得分：0)
这是Java（GUI）中的奇怪行为之一。您可以在面板上手动绘制图像。
以下是我使用的内容：
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2= (Graphics2D) g;
if (currentImage != null) {
g2.drawImage(currentImage, null, 0, 0);
}
}
此外，您应该创建一个“ImagePanel”组件，它是一个封装图像的JPanel。
drawImage的中间争论是空的，因为我不打算对它进行图像操作。