Java Exceptions

Java Exceptions

Exceptions in Java represent errors that occur during execution of a program.
Exception handling is used to avoid undesirable display errors, but also easier to correct any errors.

To handle exceptions occurred during runtime uses:
The try-catch-finally
Exception thrown by method throws

Exception example

Try-catch-finally example

public class ExceptionExample{
    public static void main(String [] args){
        try{
            System.out.println("Start");
            int a = Integer.parseInt("123abc");
        }catch(NumberFormatException ex1){
            ex1.printStackTrace();
            System.out.println("Is not numeric!");
        }catch(Exception ex2){
            ex2.printStackTrace();
        }finally{
            System.out.println("End");
        }
    }
}

Throws example

class Exception1 extends Exception {
      public Exception1() {}
}


public class TestException {
    public static void m1() throws Exception1 {
        int a=5;
        if(a>7){
            System.out.println("OK");
        }else{
            System.out.println("Exception a="+a);
            throw new Exception1();        
        }
    }
    public static void main(String[] args) {
        try {
            m1();
        } catch(Exception1 e){
            e.printStackTrace();
        }
    }
}