Java Program to Handle Checked Exception

Difficulty Level : Expert
Last Updated : 29 Oct, 2020

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.

Exceptions in Java

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.

Consider myfile.txt file does not exist.

Java

// Java Program to Handle Checked Exception 
import java.io.*; 
class GFG { 
    public static void main(String args[]) 
    { 
        FileInputStream GFG 
            = new FileInputStream("/home/mayur/GFG.txt"); 
        // this file does not exist in the location 
        /* This constructor FileInputStream 
         * throws FileNotFoundException which 
         * is a checked exception 
         */
    } 
}

Output:

Handling FileNotFoundException:

This exception can be handled with the help of a try-catch block

Declare the function using the throw keyword to avoid a Compilation error.
All the exceptions throw object 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.

Java

// Java Program to Handle Checked Exception 
import java.io.*; 
import java.util.*; 
class GFG { 
    public static void main(String[] args) 
        throws FileNotFoundException 
    { 
        FileInputStream GFG = null; 
        try { 
            GFG = new FileInputStream( 
                "/home/mayur/GFG.txt"); 
        } 
        catch (FileNotFoundException e) { 
            System.out.println("File does not exist"); 
        } 
    } 
}

Output:

ClassNotFoundException:

This Exception occurs when methods like Class.forName() and LoadClass Method etc unable to find the given class name as a parameter.

Java

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

Output:

Handling ClassNotFoundException: Using try-Catch Block

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:

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