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Java Program to Handle Checked Exception

  • Difficulty Level : Expert
  • Last Updated : 15 Nov, 2021

Checked exceptions are the subclass of the Exception class. These types of exceptions occur during the compile time of the program. These exceptions can be handled by the try-catch block otherwise the program will give a compilation error.

 ClassNotFoundException, IOException, SQLException etc are the examples of the checked exceptions.

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Java Exceptions

I/O Exception: This Program throw I/O exception because of due FileNotFoundException is a checked exception in Java. Anytime, we want to read a file from the file system, Java forces us to handle error situations where the file is not present in the given location.



Implementation: Consider myfile.txt file does not exist.

Example 1-A

Java




// Java Program to Handle Checked Exception
// Where FileInputStream Exception is thrown
 
// Importing required classes
import java.io.*;
 
// Main class
class GFG {
 
    // Main driver method
    public static void main(String args[]) {
 
        // Reading content from file by passing local directory path
        // where file should exists
        FileInputStream GFG
            = new FileInputStream("/Desktop/GFG.txt");
 
        // This file does not exist in the location
        // This constructor FileInputStream
        // throws FileNotFoundException which
        // is a checked exception
    }
}

 Output:

Now let us do discuss how to handle FileNotFoundException. The answer is quite simple as we can handle it with the help of a try-catch block 

  • Declare the function using the throw keyword to avoid a Compilation error.
  • All the exceptions throw objects when they occur try statement allows you to define a block of code to be tested for errors and catch block captures the given exception object and perform required operations.
  • Using a try-catch block defined output will be shown.

Example 1-B:

Java




// Java Program to Illustrate Handling of Checked Exception
 
// Importing required classes
import java.io.*;
import java.util.*;
 
// Main class
class GFG {
 
    // Main driver method
    public static void main(String[] args)
        throws FileNotFoundException
    {
 
        // Assigning null value to object of FileInputStream
        FileInputStream GFG = null;
 
        // Try block to check for exceptions
        try {
 
            // Giving path where file should exists to read
            // content
            GFG = new FileInputStream(
                "/home/mayur/GFG.txt");
        }
 
        // Catch block to handle exceptions
        catch (FileNotFoundException e) {
 
            // Display message when exception occurs
            System.out.println("File does not exist");
        }
    }
}
Output



File does not exist

Now let us discuss one more checked exception that is ClassNotFoundException. This Exception occurs when methods like Class.forName() and LoadClass Method etc. are unable to find the given class name as a parameter.

Example 2-A

Java




// Java Program to Handle Checked Exception
 
// Importing required classes
import java.io.*;
 
// Main class
class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Calling the clas gfg which is not present in the
        // current class temp instance of calling class
        Class temp = Class.forName("gfg");
 
        // It will throw ClassNotFoundException
    }
}

 Output:

Again now let us handle ClassNotFoundException using try-Catch block 

Example 2-B

Java




// Java Program to Handle Checked Exception
import java.io.*;
class GFG {
 
    public static void main(String[] args)
        throws ClassNotFoundException
    {
 
        try {
            Class temp = Class.forName(
                "gfg"); // calling the gfg class
        }
        catch (ClassNotFoundException e) {
            // block executes when mention exception occur
            System.out.println(
                "Class does not exist check the name of the class");
        }
    }
}
Output
Class does not exist check the name of the class



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