Java Examples - Use of Finally

Problem Description

How to use finally block for catching exceptions ?

Solution

This example shows how to use finally block to catch runtime exceptions (Illegal Argument Exception) by the use of e.getMessage().

public class ExceptionDemo2 {
   public static void main(String[] argv) {
      new ExceptionDemo2().doTheWork();
   }
   public void doTheWork() {
      Object o = null; 
      for (int i = 0; i < 5; i++) {
         try {
            o = makeObj(i);
         } catch (IllegalArgumentException e) {
            System.err.println("Error: ("+ e.getMessage()+").");
            return;   
         } finally {
            System.err.println("All done");
            if (o == null)
            System.exit(0);
         }
         System.out.println(o); 
      }
   }
   public Object makeObj(int type) throws IllegalArgumentException {
      if (type == 1)throw new IllegalArgumentException("Don't like type " + type);
      return new Object();
   }
}

Result

The above code sample will produce the following result.

All done
java.lang.Object@1b90b39
Error: (Don't like type 1).
All done

The following is an another sample example of finally block in java

public class HelloWorld { 
   public static void main(String []args) { 
      try { 
         int data = 25/5; 
         System.out.println(data);
      } catch(NullPointerException e) { 
         System.out.println(e);
      } finally { 
         System.out.println("finally block is always executed"); 
      } 
      System.out.println("rest of the code...");
   }
}

The above code sample will produce the following result.

5
finally block is always executed
rest of the code...