求教 程序运行不出来，哪里的问题？

Question

public class ych {

public class r 

{

private double radius;

public void g(double r) throws f

{

if(radius<0)

{

throw new f(r);

}

else

{

radius=r;

}

}

}

public class f extends Exception {

double radius;

  f(double r)

  {

  radius=r;

  }

  public String toString()

  {

  return "radius"+this.radius+"r";

  }

  

}

public static void main(String[] args) {

r b=new r();

     try{

     b.g(-2);

     }

     catch(f e){

     System.out.println(""+e.toString()+"");

     }

  }

}

/*

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 

at ych.main(ych.java:32)

*/

Answer 1

第一:  你的main方法是静态方法，静态方法只能调用静态变量，很显然你的R类并不是静态的，所以你要先将R类设置为static第二： 改了之后你的程序也是没有结果的，你的R类中radius没有初始化，系统默认初始化为0,所以o肯定不会小于0，所以b.g(-2)不管你传进去的参数是多少，都不会抛出异常，更不会输出

Answer 2

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