Java Program to Handle Checked Exception

04 Jul, 2022
Checked exceptions are the subclass of the Exception class. These types of exceptions need to be handled during the compile time of the program. These exceptions can be handled by the try-catch block or by using throws keyword otherwise the program will give a compilation error.
 ClassNotFoundException, IOException, SQLException etc are the examples of the checked 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 GFG.txt file does not exist.
Example 1-A
Java
// Java Program to Handle Checked Exception// Where FileInputStream Exception is thrown // Importing required classesimport java.io.*; // Main classclass 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 classesimport java.io.*;import java.util.*; // Main classclass 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");        }    }}
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 classesimport java.io.*; // Main classclass GFG {     // Main driver method    public static void main(String[] args)    {        // Calling the class 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 Exceptionimport 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");        }    }}
Class does not exist check the name of the class
solankimayank
ankur035
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java-file-handling
Technical Scripter 2020
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