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Trail: Essential Java Classes
Lesson: Handling Errors with Exceptions

## 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();
>    >             }
>    >         }
>    >     }

Check your answers.

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