I am new to java hence probably a very noob question:
I have a class
public class Foo{
private static String foo;
private String bar;
public Foo(String bar){
this.bar = bar;
}
}
Now before I instantiate any object for class Foo, I want to set that static variable foo. which will be used in the class.. How do i do this?
Also, please correct my understanding. value of foo will be same across all the objects, hence it does make sense to declare it as static ? right?
public class Foo{
private static String foo = "initial value";
private String bar;
public Foo(String bar){
this.bar = bar;
}
}
Since the value will be the same across all objects, static is the right thing to use. If the value is not only static but also never changing, then you should do this instead:
public class Foo{
private static final String FOO = "initial value";
private String bar;
public Foo(String bar){
this.bar = bar;
}
}
Notice how the capitalization changed there? That's the java convention. "Constants" are NAMED_LIKE_THIS.
foo will be shared among all instances of FooOption A
private static String foo = "static variable";
Option B
private static String foo;
static {
foo = "static variable";
}
Option B is seldom used, mostly when there are some inter-dependencies between static variables or potential exceptions.
In either case, static init will happen when the class is loaded.
As stated by the other answers, you should set your initial value like so:
private static String foo = "initial value";
Additionally, if you want to access this variable from anywhere, you need to reference it in a static context, like so:
Foo.foo
where Foo is the class name, and foo is the variable name.
This is actually very useful in understanding the concept of static variables. Rather than referencing foo as a member of some instance of the Foo class, you are referencing foo as a member of the class itself. So, for all instances of Foo, the value of foo will be the same because it is owned by the class and not the instance.
Inside the Foo class, you can get away with just calling foo without qualifying it with a class name.
private static String foo = "MyValue";Will it differ depending on run-time decisions?