牙齿矫正痛苦吗:哪位Java高手可以帮帮我啊，在线等答案！！！

编写一个java程序，让它实现以下功能：
1. 输出这样一段矩形
＊＊＊＊＊
＊＊＊＊＊
＊＊＊＊＊

＊＊＊＊
＊＊＊＊

＊＊＊＊＊＊＊＊＊＊
＊＊＊＊＊＊＊＊＊＊
＊＊＊＊＊＊＊＊＊＊
＊＊＊＊＊＊＊＊＊＊
＊＊＊＊＊＊＊＊＊＊
＊＊＊＊＊＊＊＊＊＊
2. 其中换行可以由System.out.println();这条语句来实现。

以下是改错并写出结果：：
class A
{ int a1=1;
public int a2=2;
protected int a3=3;
private int a4=4;
int geta4( ){return a4;}
}
class B extends A
{ int b=5;
int sum( ){return a1+a2+a3+a4+b;}
}

public class ClassInheritance
{ public static void main(String args[ ])
{ A aa=new A( );
System.out.println("A:"+aa.a1+"\t"+aa.a2+"\t"+aa.a3+"\t"+aa.a4);
B bb=new B( );
System.out.println("B:"+bb.a1+"\t"+bb.a2+"\t"+bb.a3+"\t"+bb.a4+
"\t"+bb.b+"\t"+bb.sum( ));
}
}

2。class Point
{ final static Point origin=new Point(0,0); //类变量、常量、坐标原点
int x,y;
Point (int x,int y)
{ x=x;
y=y;
}
}
public class UsingStatic
{ public static void main(String args[])
{ Point p1=new Point(10,20); //构造Point类的对象p1
System.out.println("类Point中的类变量：");
System.out.println("("+Point.origin.x+","+Point.origin.y+")"); //访问类变量
System.out.println("类Point中的类实例变量：");
System.out.println("("+p1.x+","+p1.y+")"); //访问类对象变量x,y
}
}
3。
class point{
int x,y;
void init(int a,int b){
x=a;y=b;
}
}

public class twoPoint {
public static void main(string[] args){
point p1=new point()
point p2=new point()
p1.x=10;
p1.y=20;
p2.x=30;
p2.y=40;
System.out.println("x="+p1.x+" y="+p1.y);
System.out.println("x="+p2.x+" y="+p2.y);
}
}