例如简单例子: public class A{ int age; public A(int a){ age = a; } public void setAge(int A_age){ age = A_age; } public int getAge(){ return age; } } class Test{ public static void main(String [] args){ A n=new A(30); System.out.println(n.getAge()); } } 其中class Test 就是内部类 它就是调用上面A类的方法。
.java:15: inner classes cannot have static declarations
同意楼上的 main方法是static的 单age是int的
class A { class B {} public void f() { class C {} }
也许对你有帮助!
import java.awt.*;
import java.awt.event.*;public class area_1
{
public static void main(String[] args)
{
Win win=new Win();
win.setBounds(100,100,200,100);
win.setVisible(true);
win.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
}
static class Win extends Frame implements ActionListener
{ MenuBar bar=null;
Menu menu=null;
MenuItem item1,item2;
yuan circle;
sanjiaoxing trangle; public Win()
{
bar=new MenuBar();
menu=new Menu("选择");
item1=new MenuItem("圆计算面积");
item2=new MenuItem("三角形计算面积");
menu.add(item1);
menu.add(item2);
bar.add(menu);
circle=new yuan();
trangle=new sanjiaoxing();
item1.addActionListener(this);
item2.addActionListener(this);
setMenuBar(bar);
setVisible(true);
setBounds(100,120,100,90);
} public void actionPerformed(ActionEvent e)
{
if(e.getSource()==item1)
{
removeAll();//移去原来所有组件
add(circle,BorderLayout.CENTER);//添加圆计算面板
validate();//保证所有添加的组件可见
}
else if(e.getSource()==item2)
{
removeAll();
add(trangle,BorderLayout.CENTER);
validate();
} } class yuan extends Panel implements ActionListener
{
double r=0,area;
TextField banjin,result_text;
Button b=null; public yuan()
{
banjin=new TextField(10);
result_text=new TextField(10);
b=new Button("确定");
add(new Label("请输入半径"));
add(banjin);
add(result_text);
add(b);
b.addActionListener(this);
} public void actionPerformed(ActionEvent e)
{
try
{
r=Double.parseDouble(banjin.getText());
area=Math.PI*r*r;
result_text.setText(""+area);
}
catch(Exception ee)
{
banjin.setText("请输入数字字符");
}
}
}
class sanjiaoxing extends Panel implements ActionListener //负责计算三角形的面积
{
double a=0,b=0,c=0,area=0;
TextField bian1=new TextField(6);
TextField bian2=new TextField(6);
TextField bian3=new TextField(6);
TextField result_text_s =new TextField(12);
Button button=new Button("确定"); sanjiaoxing()
{
add(new Label("请输入三边的长度"));
add(bian1);
add(bian2);
add(bian3);
add(button);
button.addActionListener(this);
add(new Label("三角形的面积是:"));
add(result_text_s);
} public void actionPerformed(ActionEvent e)
{
try
{
a=Double.parseDouble(bian1.getText());
b=Double.parseDouble(bian2.getText());
c=Double.parseDouble(bian3.getText());
if(a+b>c&&a+c>b&&b+c>a)
{
double p=(a+b+c)/2;
area=Math.sqrt(p*(p-a)*(p-b)*(p-c));
result_text_s.setText(""+area);
}
else
{
result_text_s.setText("你输入的三边不能形成三角形");
}
}
catch(Exception ee)
{
result_text_s.setText("请输入数字字符");
}
}
}
}
}
你会不会把楼主搞得更晕阿
public class A{
int age;
public A(int a){
age = a;
}
public void setAge(int A_age){
age = A_age;
}
public int getAge(){
return age;
}
}
class Test{
public static void main(String [] args){
A n=new A(30);
System.out.println(n.getAge());
}
}
其中class Test 就是内部类 它就是调用上面A类的方法。
class B {} public void f() {
class C {}
}
A a=new A(){};
}