Understanding Java Object Members, Methods, and Initialization

In this tutorial we explore Java object members, methods, and initialization, building on the earlier introduction to objects and classes.

We demonstrate how a method can access an object's data member by adding a getHeight() method to a Human class, and explain the role of the return statement and the implicit this reference.

public class Test {
    public static void main(String[] args) {
        Human aPerson = new Human();
        System.out.println(aPerson.getHeight());
    }
}
class Human {
    /** accessor */
    int getHeight() {
        return this.height;
    }
    int height;
}

We show that this is optional and can be omitted, and we present an alternative version of getHeight() without the explicit this .

int getHeight() {
    return height;
}

Next we introduce method parameter lists by defining a growHeight(int h) method that increases the object's height field, and we illustrate how arguments are passed and scoped.

public void growHeight(int h) {
    this.height = this.height + h;
}

We also cover calling other methods of the same object using this.method() , exemplified by a repeatBreath(int rep) method that loops and invokes breath() repeatedly.

public void repeatBreath(int rep) {
    for (int i = 0; i < rep; i++) {
        this.breath();
    }
}

Finally we discuss data member initialization, describing default values for primitive types and explicit initialization, and we provide an example where height is set to 175.

int height = 175;

The article concludes with a summary of the key points: return , this , default values, and explicit initialization.