帮忙写个java程序

import javax.swing.JOptionPane;

public class Hello extends javax.swing.JFrame {

public Hello() {
initComponents();
}
//
private void initComponents() {

jPanel1 = new javax.swing.JPanel();
jButton1 = new javax.swing.JButton();

setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("HELLO");

jPanel1.setMaximumSize(new java.awt.Dimension(200, 100));
jPanel1.setMinimumSize(new java.awt.Dimension(200, 100));

jButton1.setText("Press Me");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});

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(155, 155, 155)
.addComponent(jButton1)
.addContainerGap(162, Short.MAX_VALUE))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(129, 129, 129)
.addComponent(jButton1)
.addContainerGap(146, Short.MAX_VALUE))
);

javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);

pack();
}//

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
javax.swing.JOptionPane.showMessageDialog(null, "欢迎来到Java世界", "Hello", JOptionPane.INFORMATION_MESSAGE);
}

public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Hello().setVisible(true);

}
});
}

modify
private javax.swing.JButton jButton1;
private javax.swing.JPanel jPanel1;

}

我新手，正在做类似的东西，顺手帮你做一个
类名：Hello

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

class Frame extends JApplet{

JFrame f;

JPanel p;

JButton bu;

public Frame(){
f = new JFrame("Hello");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
f.setSize(200,100);
f.setResizable(false);
p = new JPanel();
bu = new JButton("Press Me");
p.add(bu);
f.add(p);

}
}

class sysy extends Frame {
ButtonHandle bh;

public sysy() {
bh = new ButtonHandle();

bu.addActionListener(bh);

}

class ButtonHandle implements ActionListener {
public void actionPerformed(ActionEvent e) {
Object obj = e.getSource();
//////////////////////字符串输出
System.out.println("您好! 欢迎进入Java世界!");
/////////////////////弹窗输出 不确定你说的是哪个 你选一个吧
JFrame f2=new JFrame("消息");
f2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f2.setVisible(true);
f2.setSize(150,70);
f2.setResizable(false);
JPanel p2 = new JPanel();
JLabel l= new JLabel("您好! 欢迎进入Java世界!");
p2.add(l);
f2.add(p2);

}
}
}

public class Hello {

public static void main(String[] args) {

new sysy();

}

}

import java.awt.*;
import java.awt.event.*;

class Hello extends Frame implements ActionListener{

Button b1=new Button("Press me");
Label l1=new Label();

public Hello()
{
this.setTitle("hello");
this.setSize(200, 100);
this.setLayout(new GridLayout(2,1));
this.add(b1);
this.add(l1);
b1.addActionListener(this);
this.addWindowListener(new WinClose());
this.setVisible(true);
}

public void actionPerformed(ActionEvent e)
{
if(e.getSource()==b1)
l1.setText("您好! 欢迎进入Java世界!");
}

}

class WinClose extends WindowAdapter
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
}

public class MyHello
{
public static void main(String[] args) {
// TODO 自动生成方法存根
Hello h=new Hello();
}
}

如果说界面有点丑的话就理解一下，他本来布局的这样

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class FrameTest
{
public static void main(String[] args)
{
JFrame j=new JFrame("Hello");
j.setSize(200,100);
j.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JButton b=new JButton("Press Me");
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
System.out.println("您好! 欢迎进入Java世界!");
}
}
);
j.getContentPane().add(b);
j.setVisible(true);

}

}