Java trap, a basket: the first answer and analysis 1
1.
Abstract class name {
PRIVATE STRING NAME;
Public Abstract Boolean isstupidName (String Name) {}
}
What is wrong with the heroes?
Answer: wrong. Abstract Method must end with a semicolon and do not bring a curly bracket.
2.
Public class something {
Void dosomething () {
Private string s = "";
INT L = S.LENGTH ();
}
}
Is it wrong?
Answer: wrong. Any access modifier (private, PUBLIC, and Protected) cannot be placed before the local variable. Final can be used to modify local variables (Final is like Abstract and Strictfp, all non-access modifiers, Strictfp can only modify Class and Method rather than variable).
3.
Abstract class something {
Private abstract string dosomething ();
}
It seems that there is nothing wrong?
Answer: wrong. Abstract Methods cannot be modified in private. Abstract Methods is the specific details of the subclass item, how can I use Private to block Abstract Method? (Similar to the confstract method, Final cannot be added).
4.
Public class something {
Public Int Addone (Final INT X) {
Return x;
}
}
This is more obvious.
Answer: wrong. INT X is modified to Final, meaning X cannot be modified in Addone Method.
5.
Public class something {
Public static void main (String [] args) {
Other o = new other ();
New Something (). Addone (O);
}
Public void addone (Final Other O) {
O.I ;
}
}
Class other {
Public INT I;
}
It is very similar to the above, it is about Final problem, is this wrong?
Answer: Correct. In Addone Method, the parameter O is modified into final. If we modified O's Reference in Addone Method (for example: o = new other ();), then this question is also wrong. But this is modified here that the MEMBER VAIRABLE (member variable) of O, while the REFERENCE does not change.
After 5 questions in the << Answer and Analysis 2 >>.
