Why doesn't catching Exception catch RuntimeException?

Question

This is very odd to me. RuntimeException inherits from Exception, which inherits from Throwable.

catch(Exception exc)          


        

Answer 1

class Test extends Thread
{
    public void run(){  
        try{  
            Thread.sleep(10000);  
        }catch(InterruptedException e){  
            System.out.println("test1");
            throw new RuntimeException("Thread interrupted..."+e);  
        }  

    }  

    public static void main(String args[]){  
        Test t1=new Test1();  
        t1.start();  
        try{  
            t1.interrupt();  
        }catch(Exception e){
            System.out.println("test2");
            System.out.println("Exception handled "+e);
        }  

    }  
}

Its output doesn't contain test2 , so its not handling runtime exception. @jon skeet, @Jan Zyka

Answer 2

catch (Exception ex) { ... }

WILL catch RuntimeException.

Whatever you put in catch block will be caught as well as the subclasses of it.

Answer 3

The premise of the question is flawed, because catching Exception does catch RuntimeException. Demo code:

public class Test {
    public static void main(String[] args) {
        try {
            throw new RuntimeException("Bang");
        } catch (Exception e) {
            System.out.println("I caught: " + e);
        }
    }
}

Output:

I caught: java.lang.RuntimeException: Bang

Your loop will have problems if:

• callbacks is null
• anything modifies callbacks while the loop is executing (if it were a collection rather than an array)

Perhaps that's what you're seeing?

Answer 4

Catching Exception will catch a RuntimeException

Answer 5

I faced similar scenario. It was happening because classA's initilization was dependent on classB's initialization. When classB's static block faced runtime exception, classB was not initialized. Because of this, classB did not throw any exception and classA's initialization failed too.

class A{//this class will never be initialized because class B won't intialize
  static{
    try{
      classB.someStaticMethod();
    }catch(Exception e){
      sysout("This comment will never be printed");
    }
 }
}

class B{//this class will never be initialized
 static{
    int i = 1/0;//throw run time exception 
 }

 public static void someStaticMethod(){}
}

And yes...catching Exception will catch run time exceptions as well.