How to write custom exception class in java

How to write custom exception class in java

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Custom Checked and Custom Unchecked

 · How to do this: Define new exception class, so the class name tells what happens Define a unifed/generic exception class which wraps code, message or other info. the code can tells what happens. To summarize it, Do something let your exception have some meaning/semantics, and let its client know what exactly happens. Share Improve this answer  · Then, in other classes wherever you need this exception to be raised, create an object of the created custom exception class and, throw the exception using the throw keyword. MyException ex = new MyException (); If(condition .){ throw ex; } Custom Checked and Custom Unchecked. All exceptions must be a child of Throwable  · CustomException class is the custom exception class this class is extending Exception class. Create one local variable message to store the exception message locally in the class object. We are passing a string argument to the constructor of the custom exception object. The constructor set the argument string to the private string message

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Example 1: Java program to create custom checked exception

 · In order to create a custom exception, we need to extend the Exception class that belongs to blogger.com package. Example: We pass the string to the constructor of the superclass- Exception which is obtained using the “getMessage ()” function on the object created. Java class MyException extends Exception { public MyException (String s) { super(s); } Here, we call the constructor of Exception class from the CustomException class using super () keyword. Inside the method checkLanguage (), we have checked the exception condition, and if the exception occurs, the blogger.com block handles the exception. Here, this is the checked exception. We can also create unchecked exception class in Java  · Then, in other classes wherever you need this exception to be raised, create an object of the created custom exception class and, throw the exception using the throw keyword. MyException ex = new MyException (); If(condition .){ throw ex; } Custom Checked and Custom Unchecked. All exceptions must be a child of Throwable

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Example 2: Create custom unchecked exception class

 · Writing your own exception class Create a new class whose name should end with Exception like ClassNameException. This is a convention to differentiate Make the class extends one of the exceptions which are subtypes of the blogger.comion class. Generally, a custom Create a constructor  · To make the code more realistic, you can add the custom exception to a static method in your class as follows: class Main { public static void main (String [] args) throws InvalidStringException { String myString = "Programming Language" ; checkString (myString); } static void checkString (String test) throws InvalidStringException { if (! test. contains (  · Then, in other classes wherever you need this exception to be raised, create an object of the created custom exception class and, throw the exception using the throw keyword. MyException ex = new MyException (); If(condition .){ throw ex; } Custom Checked and Custom Unchecked. All exceptions must be a child of Throwable

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Your Answer

 · ReadWrite class: public boolean writeToFile () { boolean ok; try { FileWriter writer = new FileWriter (file); { if (blogger.comrCase ().endsWith (".txt")) { ok = true; write (); } else { ok = false; } } } catch (IOException e) { ok = false; } } InvalidFileExceptionClass *****  · CustomException class is the custom exception class this class is extending Exception class. Create one local variable message to store the exception message locally in the class object. We are passing a string argument to the constructor of the custom exception object. The constructor set the argument string to the private string message  · To make the code more realistic, you can add the custom exception to a static method in your class as follows: class Main { public static void main (String [] args) throws InvalidStringException { String myString = "Programming Language" ; checkString (myString); } static void checkString (String test) throws InvalidStringException { if (! test. contains (

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Help Others, Please Share

 · In order to create a custom exception, we need to extend the Exception class that belongs to blogger.com package. Example: We pass the string to the constructor of the superclass- Exception which is obtained using the “getMessage ()” function on the object created. Java class MyException extends Exception { public MyException (String s) { super(s); }  · To create a custom exception, we have to extend the blogger.comion class. Let’s see an example of this by creating a custom checked exception called IncorrectFileNameException: public class IncorrectFileNameException extends Exception { public IncorrectFileNameException(String errorMessage) { super (errorMessage); } }Estimated Reading Time: 4 mins  · ReadWrite class: public boolean writeToFile () { boolean ok; try { FileWriter writer = new FileWriter (file); { if (blogger.comrCase ().endsWith (".txt")) { ok = true; write (); } else { ok = false; } } } catch (IOException e) { ok = false; } } InvalidFileExceptionClass *****