constructors

[Rajiv Chelsea]

Can we modify constructors with abstract keyword?

[Seetharaman Venkatasamy]

what do you think ? constructor can not be overridden right?.

[David Newton]

What happens when you try it?

[Rajiv Chelsea]

I tried the following code

public abstract class One {
abstract One();
}
class Test1 extends One {
One(){
System.out.println("Two");
}
}

It gives following errors in class "One"


1: Illegal modifier for the method One.One()
2: This method requires a body instead of a semicolon

at line 4

and in class "Test1" following error is displayed

"Return type for the method is missing" at line 10

[Rob Spoor]

 

Rajiv Chelsea wrote:and in class "Test1" following error is displayed

"Return type for the method is missing" at line 10

That's because the constructor name must match the class name, and Test1 != One.

[Jim Hoglund]

Rajiv : Did you find the answer to your question when you compiled the code ?

Jim ... ...

[Arun C. Giridharan]

well i asked my friendly compiler....... he said

public abstract class One {
abstract One();
}
class Test1 extends One {
One(){
System.out.println("Two");
}

Q.java:10: invalid method declaration; return type required
Q.java:3: modifier abstract not allowed here...... now it should be clear! !

[Jim Hoglund]

Okay, just wanted to be sure. You reported the error messages
but did not say that you understood them. Have a good week.

Jim ... ...

[David Newton]

@Jim: Er, that's not the OP.

[john chris]

sorry,I am still learning english

at line 4:

constructors need body

at line 10:

the JVM regard as it is a normal method,not aconstructor, so it need return type

[Arun C. Giridharan]

 

at line 4:

constructors need body

at line 10:

the JVM regard as it is a normal method,not aconstructor, so it need return type

When you put all together....Compiler says only normal method can be associated with abstract with return type.

[Campbell Ritchie]

Every constructor must have a name identical to the class name and no return type. If you state a return type by mistake, the compiler will take that as a method. Probably a design fault in the language, but it is too late to change now.

Every method must have a return type or void.

[Jim Hoglund]

The language does not restrict method names to exclude the class name.
If there's a return type, then it's a method, as shown in this confusing but
valid code.

class F {
public static void main(String[] args) {
new F().F();
}
void F() {
System.out.println("hi");
}
}

Jim ... ...