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Questions and Exercises: Exceptions

Questions

1. Is the following code legal?

   try {
       ...
   } finally {
       ...
   }
   

2. What exception types can be caught by the following handler?

   catch (Exception e) {
       ...
   }
   

   What is wrong with using this type of exception handler?

3. What exceptions can be caught by the following handler?

   ...
   } catch (Exception e) {
       ...
   } catch (ArithmeticException a) {
       ...
   }
   

   Is there anything wrong with this exception handler as written? Will this code compile?

4. Match each situation in the first column with an item in the second column.

   int[] A; A[0] = 0; The Java VM starts running your program, but the VM can’t find the Java platform classes. (The Java platform classes reside in classes.zip or rt.jar.) A program is reading a stream and reaches the end of stream marker. Before closing the stream and after reaching the end of stream marker, a program tries to read the stream again.

   error checked exception runtime exception no exception

Exercises

1. Add a readList method to ListOfNumbers.java. This method should read in int values from a file, print each value, and append them to the end of the vector. You should catch all appropriate errors. You will also need a text file containing numbers to read in.

2. Modify the following cat method so that it will compile:

   public static void cat(File named) {
       RandomAccessFile input = null;
       String line = null;
   
       try {
           input = new RandomAccessFile(named, "r");
           while ((line = input.readLine()) != null) {
               System.out.println(line);
           }
           return;
       } finally {
           if (input != null) {
               input.close();
           }
       }
   }
   

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