JAVA: try, catch, throw & throws di Java

Apakah 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.

Pengecualian adalah "peristiwa yang tidak diinginkan atau tidak terduga", yang terjadi selama eksekusi program yaitu, pada saat run-time, yang mengganggu aliran normal instruksi program. Ketika pengecualian terjadi, eksekusi program dihentikan.

Mengapa Exception terjadi?

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

Pengecualian dapat terjadi karena beberapa alasan seperti masalah koneksi jaringan, Input buruk yang diberikan oleh pengguna, Membuka file yang tidak ada di program Anda, dll.

Block & Keyword yang digunakan untuk menangani exception

1.try:

The try block contains set of statements where an exception can occur.

Blok try berisi serangkaian pernyataan di mana pengecualian dapat terjadi.

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 block digunakan untuk menangani kondisi try block yang tidak pasti. Blok try selalu diikuti oleh blok catch, yang menangani pengecualian yang terjadi di blok try terkait.

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.

Throw keyword digunakan untuk mentransfer control dari try block ke 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.

Kata kunci Throws digunakan untuk penanganan exception tanpa blok try & catch. Ini menentukan pengecualian yang dapat dilemparkan oleh suatu metode ke pemanggil dan tidak menangani dirinya sendiri.

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 :

Itu dieksekusi setelah blok tangkapan. Kami pada dasarnya menggunakannya untuk meletakkan beberapa kode umum ketika ada beberapa blok tangkapan.

Contoh Exception yang dihasilkan oleh sistem diberikan di bawah ini:

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

Contoh throw 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.");
        }
    }
}