class Myclass{
int x;
Myclass (int i){
x = i;
}
}
That is the code I have in my book. I wanted to know if this code would work?
class Myclass{
int x;
Myclass (x)
}
I also could try
class Myclass{
int x;
Myclass (int x)
}
in response to my first answer...would this work?
The latter code would not work because in Java you have to explicitly state the type. (There are no implicit type declarations)
this.x = x;You may have a parameter or local variable with the same name as an instance variable, yes. In that case, the parameter or local variable will shadow the instance variable. To refer to the instance variable in such a case, use:
this.x
For example, it's common to see this pattern:
class MyClass {
private int x;
public MyClass(int x) {
this.x = x;
}
}
Note that, as Josh M points out, it is not possible to omit the type. If that is what your question was about, then no, you may not.
This will compile:
class Myclass {
int x;
Myclass (int x) {
}
}
However, when you do this you end up with two variables with the same name, the instance variable x, which can be referred to explicitly inside the constructor (or any other class method) as this.x, and the local parameter variable x local to the constructor. If you just refer to x in the constructor you'll get the local one. This is referred to as variable shadowing.
Even though you've decided to give these two variables the same names in your source code, in the code the compiler produces they are completely unrelated. You might as well have named the parameter y.
An experiment to try that might help understanding this is to give the variables different types. Make your instance variable a boolean, for instance. Then you can try different things and see that they really are completely different variables that just happen to have the same name.
After @Chris Hayes' and @Samuel Edwin Ward's answers, here's one trick.
class MyClass {
private int x;
public MyClass(final int x) {
this.x = x;
}
}
The final modifier tells the compiler that that x cannot be modified. If you accidentally write
class MyClass {
private int x;
public MyClass(final int x) {
x = x; // Oopsie!
}
}
the compiler will complain.
JAVA_HOMEenvironment variable to your installation directory? Did you add%JAVA_HOME%\binto yourPATH(or$JAVA_HOME/bin, if you use OSX or Linux)?