请注意，我是新手Java程序员，之前只用过C#开发桌面应用。
我刚刚创建了一个全新的项目，并想在窗口打开时加载内容。我有一个带有JPanel（Swing）的JFrame，经过多次尝试，我发现“windowOpened”是C＃中“onload”方法的等效项。但当我尝试使用此事件来加载内容时，尝试多次后我仍然得不到任何东西，于是我简单调用了System.out.print("Test");。
JFrame成功加载，但是控制台上没有出现消息，直到我关闭了窗口。后来我添加了一个按钮玩耍，用相同的打印操作，但是在单击按钮时我在控制台上没有看到任何输出，除非我重复点击5到6次，这很奇怪。因此，我在打印语句后添加了一个showMessageDialog，结果很惊讶，信息对话框按预期工作，但在重复点击多次后才显示打印的消息。
这是我第三次尝试加载内容的全新项目，但它们似乎都是以相同的方式工作的，请问这是我的电脑问题还是Java的正常行为？我能改变这种行为吗？正确的做法是什么？
这是控制台日志：
cd PATH\NetBeansProjects\mavenproject1; "JAVA_HOME=C:\\Program Files\\Java\\jdk-16.0.2" cmd /c "\"PATH" -Dexec.vmArgs= -Dexec.args=\"${exec.vmArgs} -classpath %classpath ${exec.mainClass} ${exec.appArgs}\" -Dexec.appArgs= -Dexec.mainClass=.mavenproject1.NewJFrame -Dexec.executable=\"PATH" -Dmaven.ext.class.path=\"PATH"
Running NetBeans Compile On Save execution. Phase execution is skipped and output directories of dependency projects (with Compile on Save turned on) will be used instead of their jar artifacts.
Scanning for projects...
-----------------------< mavenproject1 >------------------------
Building mavenproject1 1.0
--------------------------------[ jar ]---------------------------------
--- exec-maven-plugin:3.0.0:exec (default-cli) @ mavenproject1 ---
not working as expectednot working as expectednot working as expectednot working as expectednot working as expectednot working as expectednot working as expectednot working as expectednot working as expectednot working as expectednot working as expectednot working as expected
------------------------------------------------------------------------
BUILD SUCCESS
------------------------------------------------------------------------
Total time: 13.098 s
Finished at: 2021-08-16T17:14:40-05:00
------------------------------------------------------------------------
以下是代码：
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package .mavenproject1;
import javax.swing.JOptionPane;
/**
*
* @author
*/
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">
private void initComponents() {
jButton1 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
addWindowListener(new java.awt.event.WindowAdapter() {
public void windowOpened(java.awt.event.WindowEvent evt) {
formWindowOpened(evt);
}
});
jButton1.setText("jButton1");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
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(196, Short.MAX_VALUE)
.addComponent(jButton1)
.addGap(131, 131, 131))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap(196, Short.MAX_VALUE)
.addComponent(jButton1)
.addGap(79, 79, 79))
);
pack();
}// </editor-fold>
private void formWindowOpened(java.awt.event.WindowEvent evt) {
System.out.print("not working as expected");
}
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
System.out.print("not working as expected");
javax.swing.JOptionPane.showMessageDialog(this,"","",JOptionPane.OK_OPTION);
}
/**
* @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
private javax.swing.JButton jButton1;
// End of variables declaration
}
PrintStream（这是System.out流的类型）。 - apangin