Question

3. Handling exceptions with a finally clause

a. Download the following file from the class website: TestFinally.java

b. Examine the code to determine what it does.

c. Compile the code and notice the error.

d. Modify TestFinally.java to handle the exception following these instructions (and those embedded in the code):

i. Embedded in the code is a note showing the location for the try statement.

ii. The first line of the catch block should look like this: catch(IOException e) {

iii. Display a meaningful error message to indicate the error that has occurred and include the following statement in your catch clause: System.out.println("The exception is: " + e);

iv. Even when an error occurs in a method, there may be clean - up activities that are required before the method or program terminates. In this case, any open files should be closed prior to terminating the program.

v. Include a finally block that closes the files using notes 4 and 5 in the code that show where to place the beginning and end of the block.

vi. You will need to add a try - catch block inside the finally block to handle any IOExceptions associated with the file close operation.

e. Test your code. When it is working, you will generate another type of exception.

f. Add a second catch clause inside the finally block with a meaningful message to handle this new exception

TestFinally.java is as follows:

import java.io.*;

public class TestFinally{

public static void main(String[] args){

FileInputStream in1 = null;

FileInputStream in2 = null;

//Open an existing file trycatch.txt

File inputFile1 = new File("trycatch.txt");

//Open a non-existent file nosuchfile.abc

File inputFile2 = new File("nosuchfile.abc");

//1. Add the try statement here

//Get file handlers in Byte Stream format

in1 = new FileInputStream(inputFile1);

in2 = new FileInputStream(inputFile2);

int c1;

//Try to read 'nosuchfile.abc' till the end of File

while ((c1 = in2.read()) != -1){

System.out.println("Read from nosuchfile.abc");

}

//2. Close the try block here

//3. Add a catch block containing meaningful error messages.

//4. Add the finally block here. See instructions in the handout.

//Close the files

in1.close();

System.out.println("Closing file 'trycatch.txt' inside finally block.");

in2.close();

System.out.println("Closing file 'nosuchfile.abc' inside finally block.");

//5. Close the finally block here.

}

}

Answer 1

CODE:

//////////////////////////////////////////////////
//TestFinally.java

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
public class TestFinally {
public static void main(String[] args) {
FileInputStream in1 = null;
FileInputStream in2 = null;
//Open existing file
File inputFile1 = new File("trycatch.txt");
//Open nonexistent file
File inputFile2 = new File("nosuchfile.abc");
//1. Add try here
try {
//Get the file handlers
in1 = new FileInputStream(inputFile1);
in2 = new FileInputStream(inputFile2);
int c1;
//try to read noexistent file
while((c1 = in2.read()) != -1) {
System.out.println("Read from nosuchfile.abc");
}
//2. Close the try block
} catch(FileNotFoundException ex) {
//Catch the Runtime - FileNotFound exception (Chegg - related to query #f in the instructions)
System.out.println("Error: " + ex.getMessage());
} catch(IOException e) {
//3. Add a catch block
System.out.println("The exception is:" + e);
} finally {
//4. Add finally block
//Close the files
try {
in1.close();
} catch (Exception e) {
// Ignore exception
}
System.out.println("Closing file trycatch.txt inside finally block");
try {
in2.close();
} catch (Exception e) {
// Ignore exception
}
System.out.println("Closing file nosuchfile.abc inside finally block");
//5. Close the finally block
}

}