Java编译错误：类AppletPrac是公开的，应在名为appletprac.java的文件中声明
编译 Java 程序时，出现以下错误：
类
Appletprac是公共的，应该在名为Appletprac.java的文件中声明
这是我的 Java 代码：
import java.applet.*;
import java.awt.*; // Graphics Class
import javax.swing.*;
import java.awt.event.*;
/*<applet code="Appletprac.class" width="500" height="500"> </applet>*/
public class Appletprac extends JApplet implements ActionListener
{
JButton OK;
JRadioButton Font_Style1,Font_Style2,Font_Style3;
ButtonGroup bg;
JCheckBox Font_Family_Name;
JTextField jt;
int i;
String s="";
public void init()
{
OK=new JButton("OK");
Font_Family_Name=new JCheckBox("Serif");
Font_Style1=new JRadioButton("Plain");
Font_Style2=new JRadioButton("Bold");
Font_Style3=new JRadioButton("BoldItalic");
bg=new ButtonGroup();
jt=new JTextField(20);
this.setLayout(new FlowLayout());
bg.add(Font_Style1);
bg.add(Font_Style2);
bg.add(Font_Style3);
this.add(jt);
this.add(OK);
this.add(Font_Family_Name);
this.add(Font_Style1);
this.add(Font_Style2);
this.add(Font_Style3);
OK.addActionListener(this);
Font_Style1.addActionListener(this);
Font_Style2.addActionListener(this);
Font_Style3.addActionListener(this);
}
public void start()
{}
public void stop()
{}
public void paint(Graphics g)
{
g.clearRect(50,50,500,300);
g.draw3DRect(50,50,500,300,false);
g.setFont(new Font(s,i,30));
g.setColor(Color.BLUE);
g.drawString(jt.getText(),100,100);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==Font_Style1)
i=Font.PLAIN;
if(e.getSource()==Font_Style2)
i=Font.BOLD;
if(e.getSource()==Font_Style3)
{
i=Font.ITALIC;
int j=Font.BOLD;
i=i+j;
}
if(e.getSource()==Font_Family_Name || e.getSource()==OK)
{
if(Font_Family_Name.isSelected())
s="Serif";
else
s="Tall paul";
}
repaint();
}
}
When compiling the Java program, I am getting this error:
class
Appletpracis public, should be declared in a file namedAppletprac.java
Here is my Java code:
import java.applet.*;
import java.awt.*; // Graphics Class
import javax.swing.*;
import java.awt.event.*;
/*<applet code="Appletprac.class" width="500" height="500"> </applet>*/
public class Appletprac extends JApplet implements ActionListener
{
JButton OK;
JRadioButton Font_Style1,Font_Style2,Font_Style3;
ButtonGroup bg;
JCheckBox Font_Family_Name;
JTextField jt;
int i;
String s="";
public void init()
{
OK=new JButton("OK");
Font_Family_Name=new JCheckBox("Serif");
Font_Style1=new JRadioButton("Plain");
Font_Style2=new JRadioButton("Bold");
Font_Style3=new JRadioButton("BoldItalic");
bg=new ButtonGroup();
jt=new JTextField(20);
this.setLayout(new FlowLayout());
bg.add(Font_Style1);
bg.add(Font_Style2);
bg.add(Font_Style3);
this.add(jt);
this.add(OK);
this.add(Font_Family_Name);
this.add(Font_Style1);
this.add(Font_Style2);
this.add(Font_Style3);
OK.addActionListener(this);
Font_Style1.addActionListener(this);
Font_Style2.addActionListener(this);
Font_Style3.addActionListener(this);
}
public void start()
{}
public void stop()
{}
public void paint(Graphics g)
{
g.clearRect(50,50,500,300);
g.draw3DRect(50,50,500,300,false);
g.setFont(new Font(s,i,30));
g.setColor(Color.BLUE);
g.drawString(jt.getText(),100,100);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==Font_Style1)
i=Font.PLAIN;
if(e.getSource()==Font_Style2)
i=Font.BOLD;
if(e.getSource()==Font_Style3)
{
i=Font.ITALIC;
int j=Font.BOLD;
i=i+j;
}
if(e.getSource()==Font_Family_Name || e.getSource()==OK)
{
if(Font_Family_Name.isSelected())
s="Serif";
else
s="Tall paul";
}
repaint();
}
}
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Java每个文件允许一个公共类，并且公共类名称应与文件名相同。对于您来说，您应该制作文件名appletprac.java，
您可以看到此链接为什么Java中的文件名与类名称相同？
写下这样的html文件：
test.html
将编译的.class文件放在同一文件夹中，然后输入
appletViewer test.html在CMD中。Java allow one public class per file, and the public class name should be the same with the file name. For you , you should make the filename Appletprac.java
You can see this link Why are filenames in Java the same as the class name?
Write a html file like this:
test.html
Put the compiled .class file in the same folder, and input
appletviewer test.htmlin the cmd.如果您的外部类具有
public修饰符，则它应该位于具有相同类名和.java扩展名的文件中。这是一个简单的 java 约定，用于在文件系统中构造类和包。If your outer class has a
publicmodifier it should be in the file with the same class name and.javaextention. This is a simple java convention to structure classes and packages in the filesystem.