macOS Mutator Methods

[Dr. No]

Can someone show me the way to set up a Mutator method in Java

 

[jeremy.king]

Mutator is just a fancy pants term for a setter.

So if your class has an instance variable you would create an appropriate getter and setter method - its that whole encapsulation madness at play here. Convention is a mixed case method name with get and set used as the prefix on the method name.

public class MutatorExample {

	private String myField;
	
	
	/**
	 * Accessor/Getter
	 */
	public String getMyField() {
		return myField;
	}

	/**
	 * Mutator/Setter
	 */
	public void setMyField(String myField) {
		this.myField = myField;
	}
}

 

[Dr. No]

Thanks!

 

[NewbieNerd]

I haven't looked at Java 5.0 at all....I know they added generics to match C#, but not the get and set keywords? In C# you can do

public class Person
{
    private string name;

    public string Name
    {
        get { return name; }
        set { name = value; }
    }
}

and you can just say, if p is a Person,

string s = p.Name;
p.Name = s;

Java still not up to C# level yet?

 

[jeremy.king]

public class Person
{
    private string name;

    public string Name
    {
        get { return name; }
        set { name = value; }
    }
}

Exactly why is this better ? So you can reference member fields by a pseudonym rather than method calls, so what. Heck might as well just make your member public and access it directly. I fail to see your beef.

 

[NewbieNerd]

Exactly why is this better ? So you can reference member fields by a pseudonym rather than method calls, so what. Heck might as well just make your member public and access it directly. I fail to see your beef.

Well that was just a simple example. The point is that I can still protect the internals of my class yet have the simplicity of p.Name rather than p.getName. If the field at hand can be mutated, maybe you want to send a clone of it rather than the field itself, etc. You can put any code you want in the get/set blocks, just as in getName and setName, but still access the field in a clean way that looks like you just made the field public.

Another example: suppose a class had counter variable count that needed to be incremented. I could define a method called incrementCount, or I could do this:

p.Count++;

In Java the equivalent would be

p.setCount(p.getCount()+1);

Also note that I don't have to use BOTH get and set. Maybe I wanted read only access to the name. So I could still be able to read p.Name, just not set to it, which you couldn't do by just making the field public to get this simplicity.

A minor point, I agree, but any efforts to keep code neat and simple is worthwhile.

 

[cemorris]

Just wanted to throw out my 2 cents here. It is better to return a copy of your variable instead of the actual variable. If you return your private variable the caller method can now modify the classes private variable.