I only know that if I don't want to "try and catch" a Checked Exception,I can "throws" it away,and if I want to show some mistake message,I can "throw" a Runtime Excepiton/Checked Exception object in a method.
If I "throw" a Checked Exception object in a method ,I have to "throws" it in the method declearation,or it will compile error.
My problem is that,"if we throw a Runtime Excepitonobject,why don't we need to throws it?".
What time shoud we "throws" a Runtime Excepiton ?