Usually, you write this syntax to create an instance.
Father myFather = new Father();
Then we consider family relation of a father and his children then write this.
public class Father {
public Father() {
}
}
public class ChildA {
public void getFather() {
return new Father();
}
}
public class ChildB {
public Father getFather() {
return new Father();
}
}
public class Family {
public static void main(String[] args) {
ChildA mChildA = new ChildA();
ChildB mChildB = new ChildB();
if (mChildA.getFather().equals(mChildB.getFather())) {
System.out.println("Same father.");
} else {
System.out.println("Difference father.");
}
}
}
Oh my god, we get the terrible result.
Result:
Difference father.
We have to modify.
public class Father {
private static Father mFather = new Father();
public static Father getInstance () {
return mFather;
}
}
public class ChildA {
public Father getFather() {
return Father.getInstance();
}
}
public class ChildB {
public Father getFather() {
return Father.getInstance();
}
}
Summary :
getInstance() is not a Java reserved name.
But it is a potential standard which we want only one instance when class be created.
