这是一个迷你项目,演示了完全相同的问题(只有 2 行):https://www.dropbox.com/s/fpgkrr7a4z1zdai/JButton%20problem.zip?dl=0
我在 JFrame 类中有一个按钮,代码如下:
correlation.performCalculations(numOfRows, corrResult)
correlation.displayGraph(posBar);
correlation 是 Correlation 类的实例,它有 2 个方法:
public void performCalculations(JLabel numOfRows, JLabel corrResult) {
numOfRows.setText("Number of records showing: " + filteredCars.size());
//
// some calculation code
//
correlationResult = (double) (topPartOfEquation / bottomPartOfEquation);
corrResult.setText("Correlation: " + String.format("%.4f", correlationResult));
}
public void displayGraph(JButton posBar) {
System.out.println("I am here");
posBar.setSize(posBar.getWidth(), 92);
posBar.setLocation(posBar.getLocation().x, (posBar.getLocation().y - 92));
}
所以我遇到的问题是,当我第一次按下 JFrame 中的按钮时,它在输出中显示“我在这里”,但它不会重新调整按钮大小或重新定位它,但是如果我再次按下它,然后它就会执行此操作(调整 posBar 按钮的大小并重新定位)。第一个方法中的 JLabels 在第一次单击时更新,但只有在第二次单击时 posBar 按钮才会调整大小和重新定位。
我在第一次和第二次按下按钮时收到消息“我在这里”,但它在第二次按下时以第二种方法设置按钮的大小和位置。第一次按下时它不会对 posBar 按钮执行任何操作。
我不知道这是否有帮助,但 JLabels 和 posBar 按钮位于不同的面板中。
任何帮助将不胜感激。如果您有任何疑问请问我。
public class NewJFrame extends javax.swing.JFrame {
/**
* Creates new form NewJFrame
*/
public NewJFrame() {
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">//GEN-BEGIN:initComponents
private void initComponents() {
jPanel1 = new javax.swing.JPanel();
jLabel1 = new javax.swing.JLabel();
jPanel2 = new javax.swing.JPanel();
jButton1 = new javax.swing.JButton();
jButton2 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jPanel1.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
jLabel1.setText("jLabel1");
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(27, 27, 27)
.addComponent(jLabel1)
.addContainerGap(32, Short.MAX_VALUE))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(37, 37, 37)
.addComponent(jLabel1)
.addContainerGap(47, Short.MAX_VALUE))
);
jPanel2.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
jButton1.setText("posBar");
javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGap(22, 22, 22)
.addComponent(jButton1)
.addContainerGap(23, Short.MAX_VALUE))
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGap(38, 38, 38)
.addComponent(jButton1)
.addContainerGap(37, Short.MAX_VALUE))
);
jButton2.setText("Press Me (Twice)");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(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()
.addGap(51, 51, 51)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jButton2))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 55, Short.MAX_VALUE)
.addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(43, 43, 43))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGap(39, 39, 39)
.addComponent(jButton2)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 83, Short.MAX_VALUE)
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(51, 51, 51))
.addGroup(layout.createSequentialGroup()
.addGap(68, 68, 68)
.addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
pack();
}// </editor-fold>//GEN-END:initComponents
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_jButton2ActionPerformed
jLabel1.setText("Test");
jButton1.setSize(20, 20);
}//GEN-LAST:event_jButton2ActionPerformed
/**
* @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(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(NewJFrame.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 NewJFrame().setVisible(true);
}
});
}
// Variables declaration - do not modify//GEN-BEGIN:variables
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JLabel jLabel1;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
// End of variables declaration//GEN-END:variables
}
最佳答案
您的问题是您忽略了布局管理器以及它们对组件大小调整的作用。您的 JButton 保存在使用 GroupLayout 的容器中,并根据该布局及其规则调整大小。如果您坚持进行绝对大小调整和定位,则必须将其保存在使用空布局的容器中。如果您不移动它,这可以是包装容器/JPanel。
例如:
jButton1.setText("posBar");
jButton1.setSize(jButton1.getPreferredSize()); // required if using null layout
JPanel jButton1Panel = new JPanel(); // added
jButton1Panel.setLayout(null); // generally frowned upon
jButton1Panel.setPreferredSize(jButton1.getPreferredSize()); // so wrapper is same size as JButton
jButton1Panel.add(jButton1); // add button to wrapper
javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGap(22, 22, 22)
.addComponent(jButton1Panel) // ******* note change!! *******
.addContainerGap(23, Short.MAX_VALUE))
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGap(38, 38, 38)
.addComponent(jButton1Panel) // ******* note change!! *******
.addContainerGap(37, Short.MAX_VALUE))
);
这仅在您缩小按钮时才有效。对于更详细、更大的更改,您需要避免使用 GroupLayout 并使用对程序员更友好的布局。
另请注意,空布局和 setBounds()
在使用它们时可能会造成严重的困难。当 GUI 调整大小时,它们不会调整组件的大小,它们是增强或维护的皇家女巫,放置在滚动 Pane 中时它们完全失败,在所有平台或与原始分辨率不同的屏幕分辨率上查看时,它们看起来非常糟糕.
所以底线,
- 对于
setSize(...)
和setLocation(...)
(或组合为setBounds(...)
)工作时,需要将组件放置到使用null
布局的容器中。 - 但是话虽如此,
null
布局是有问题的,因此,如果可能的话,请尝试寻找并使用更好的解决方案 - 具体的解决方案取决于 GUI 的具体要求。<
关于Java swing,JButton 在第一次按下按钮时不会重新调整大小,但会在第二次按下时重新调整大小,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/49578311/