Confusion over method parameter and instance variable having same name

Question

    class Employee {
       public String name = "John";
       public void modifyName(String name)
       {
          name = name;     // I know using 'this' would be helpful, but I dont want to
       }
       System.out.println(name);
    }

     class Someclass {
         public static void main(String[] args)
         {
            Employee e1 = new Employee();
            System.out.println(e1.modifyName("Dave"));
            System.out.println(e1.name);  // Does this outputs John or Dave?
         }
     }

Does the method modifyName behave like a setter and change the instance variable name to be "Dave"?

Do methods only behave like a setter when they follow the naming convention setProperty?

modifyName is not working, will it work if it is named setName?

Answer 1

Within a method, a method parameter takes precedence over an instance variable. The method modifyName refers to method parameter name, not the instance variable name.

Answer 2

It prints "John"

Saying you don't want to use "this." is just ridiculous. It takes almost no effort to type and vastly improves code quality.

If you don't want to follow Java standards for code style, use inName and then name = inName; or somesuch.

Answer 3

In modifyName, the name parameter would hide the isntance member, and therefore the instance member won't be set (e1.modifyName("Dave") would change nothing). You should either write this.name = name; or use a different name for the instance member.

Does the method modifyName cannot be a setter only because of the naming convetion? modifyName() treats name as method parameter just because of not using JavaBean naming conventions?

The behavior has nothing to do with the naming convention of the method. It would behave the same if you change it to setName. The only thing that would make a difference is changing the parameter name or instance member name, to make them different.

Answer 4

If you don't use this for instance variable. Then you are just playing with the method variable in the following statement:

      name = name;     // I know using 'this' would be helpful, but I dont want to

asa result, nothing will be changed

Answer 5

Within a method block local variable will be used (if the name is same as that of the global variable). Hence there will be no change in the global variable. That's why it is mandatory over here to use this operator to access global variable.

Answer 6

To directly answer your question, no the naming convention of the method does not cause it to act as a setter.

If that were the case, there would be no need for a method body.

public void setName(String name) {
}

would behave the same as

public void setName(String name) {
    this.name = "I don't care what name you gave";
}

Which is not the case at all.

The reason your particular method is not working, is because of the statement:

// I know using 'this' would be helpful, but I dont want to

The reason that you use this.name is to distinguish between the method parameter and the instance member. The instance member is shadowed by the parameter, so without this.name you are simply overwriting the method parameter with itself.

If you absolutely refuse to use this.name for whatever (silly) reason then you should change the name of the parameter:

public void modifyName(String iHateUsingThis) {
    name = iHateUsingThis;
}