Difference between revisions of "JAVA: try, catch, throw & throws di Java"
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1.try: The try block contains set of statements where an exception can occur. | 1.try: The try block contains set of statements where an exception can occur. | ||
− | try | + | try |
− | { | + | { |
− | + | // statement(s) that might cause exception | |
− | } | + | } |
+ | |||
2.catch : Catch block is used to handle the uncertain condition of try block. A try block is always followed by a catch block, which handles the exception that occurs in associated try block. | 2.catch : Catch block is used to handle the uncertain condition of try block. A try block is always followed by a catch block, which handles the exception that occurs in associated try block. | ||
− | catch | + | catch |
− | { | + | { |
− | + | // statement(s) that handle an exception | |
− | + | // examples, closing a connection, closing | |
− | + | // file, exiting the process after writing | |
− | + | // details to a log file. | |
− | } | + | } |
3.throw: Throw keyword is used to transfer control from try block to catch block. | 3.throw: Throw keyword is used to transfer control from try block to catch block. | ||
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Example of an Exception generated by system is given below : | Example of an Exception generated by system is given below : | ||
− | Exception in thread "main" | + | Exception in thread "main" |
− | java.lang.ArithmeticException: divide | + | java.lang.ArithmeticException: divide |
− | by zero at ExceptionDemo.main(ExceptionDemo.java:5) | + | by zero at ExceptionDemo.main(ExceptionDemo.java:5) |
− | ExceptionDemo: The class name | + | ExceptionDemo: The class name |
− | main:The method name | + | main:The method name |
− | ExceptionDemo.java:The file name | + | ExceptionDemo.java:The file name |
− | java:5:line number | + | java:5:line number |
+ | |||
+ | // Java program to demonstrate working of try, | ||
+ | // catch and finally | ||
+ | |||
+ | class Division { | ||
+ | public static void main(String[] args) | ||
+ | { | ||
+ | int a = 10, b = 5, c = 5, result; | ||
+ | try { | ||
+ | result = a / (b - c); | ||
+ | System.out.println("result" + result); | ||
+ | } | ||
+ | |||
+ | catch (ArithmeticException e) { | ||
+ | System.out.println("Exception caught:Division by zero"); | ||
+ | } | ||
+ | |||
+ | finally { | ||
+ | System.out.println("I am in final block"); | ||
+ | } | ||
+ | } | ||
+ | } | ||
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Output: | Output: | ||
− | Exception caught:Division by zero | + | Exception caught:Division by zero |
− | I am in final block | + | I am in final block |
An example of throws keyword: | An example of throws keyword: | ||
− | // Java program to demonstrate working of throws | + | // Java program to demonstrate working of throws |
− | class ThrowsExecp { | + | class ThrowsExecp { |
− | + | ||
− | + | // This method throws an exception | |
− | + | // to be handled | |
− | + | // by caller or caller | |
− | + | // of caller and so on. | |
− | + | static void fun() throws IllegalAccessException | |
− | + | { | |
− | + | System.out.println("Inside fun(). "); | |
− | + | throw new IllegalAccessException("demo"); | |
− | + | } | |
− | + | ||
− | + | // This is a caller function | |
− | + | public static void main(String args[]) | |
− | + | { | |
− | + | try { | |
− | + | fun(); | |
− | + | } | |
− | + | catch (IllegalAccessException e) { | |
− | + | System.out.println("caught in main."); | |
− | + | } | |
− | + | } | |
− | } | + | } |
+ | |||
Output: | Output: | ||
− | Inside fun(). | + | Inside fun(). |
− | caught in main. | + | caught in main. |
==Referensi== | ==Referensi== | ||
* https://www.geeksforgeeks.org/try-catch-throw-and-throws-in-java/ | * https://www.geeksforgeeks.org/try-catch-throw-and-throws-in-java/ |
Revision as of 09:00, 11 May 2022
What is an Exception? An exception is an “unwanted or unexpected event”, which occurs during the execution of the program i.e, at run-time, that disrupts the normal flow of the program’s instructions. When an exception occurs, execution of the program gets terminated.
Why does an Exception occur? An exception can occur due to several reasons like Network connection problem, Bad input provided by user, Opening a non-existing file in your program etc
Blocks & Keywords used for exception handling
1.try: The try block contains set of statements where an exception can occur.
try { // statement(s) that might cause exception }
2.catch : Catch block is used to handle the uncertain condition of try block. A try block is always followed by a catch block, which handles the exception that occurs in associated try block.
catch { // statement(s) that handle an exception // examples, closing a connection, closing // file, exiting the process after writing // details to a log file. }
3.throw: Throw keyword is used to transfer control from try block to catch block.
4.throws: Throws keyword is used for exception handling without try & catch block. It specifies the exceptions that a method can throw to the caller and does not handle itself.
5.finally: It is executed after catch block. We basically use it to put some common code when there are multiple catch blocks.
Example of an Exception generated by system is given below :
Exception in thread "main" java.lang.ArithmeticException: divide by zero at ExceptionDemo.main(ExceptionDemo.java:5) ExceptionDemo: The class name main:The method name ExceptionDemo.java:The file name java:5:line number // Java program to demonstrate working of try, // catch and finally class Division { public static void main(String[] args) { int a = 10, b = 5, c = 5, result; try { result = a / (b - c); System.out.println("result" + result); } catch (ArithmeticException e) { System.out.println("Exception caught:Division by zero"); } finally { System.out.println("I am in final block"); } } }
Output:
Exception caught:Division by zero I am in final block
An example of throws keyword:
// Java program to demonstrate working of throws class ThrowsExecp { // This method throws an exception // to be handled // by caller or caller // of caller and so on. static void fun() throws IllegalAccessException { System.out.println("Inside fun(). "); throw new IllegalAccessException("demo"); } // This is a caller function public static void main(String args[]) { try { fun(); } catch (IllegalAccessException e) { System.out.println("caught in main."); } } }
Output:
Inside fun(). caught in main.