Difference between throw and throws in Java? [duplicate]
Can any one clearly state the difference between throw and throws in Java exception handling with an example? I have tried googling but couldn't arrive at a conclusion. Pls help
Solution 1:
throws
clause is used to declare an exception andthrow
keyword is used to throw an exception explicitly.If we see syntax wise then
throw
is followed by an instance variable andthrows
is followed by exception class names.The keyword
throw
is used inside method body to invoke an exception andthrows
clause is used in method declaration (signature).
For example
throw
throw new Exception("You have some exception")
throw new IOException("Connection failed!!")
throws
public int myMethod() throws IOException, ArithmeticException, NullPointerException {}
You cannot declare multiple exceptions with
throw
. You can declare multiple exception e.g. public void method()throws IOException,SQLException.checked exceptions can not be propagated with
throw
only because it is explicitly used to throw an particular exception. checked exception can be propagated withthrows
.
Exception propagation: An exception propagates from method to method, up the call stack, until it's caught. So if a() calls b(), which calls c(), which calls d(), and if d() throws an exception, the exception will propagate from d to c to b to a, unless one of these methods catches the exception. what is exception propagation?
Solution 2:
throw
use for throwing actual Exception
and throws
declare at method it might throws Exception
.
public int findMax(int[] array) throws Exception{
if(array==null)
throw new NullPointerException(...);
...
}