Introduction to Classes, Objects, Methods and Strings - Java: How to Program Early Objects - page 82

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// Fig. 3.5: Account.java

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// Account class with a constructor that initializes the name.

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4

public class Account

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{

6 private String name; // instance variable

7
8 // constructor initializes name with parameter name

public Account(String name) // constructor name is class name
{
this .name = name;
}

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10

11

12

13
14 // method to set the name

15 public void setName(String name)

16 {

17 this .name = name;

18 }

19
20 // method to retrieve the name

21 public String getName()

22 {

23 return name;

24 }

25 } // end class Account

Fig. 3.5 | Account class with a constructor that initializes the name .

Account Constructor Declaration
Lines 9-12 of Fig. 3.5 declare Account 's constructor. A constructor must have the same name
as the class. A constructor's parameter list specifies that the constructor requires one or more
pieces of data to perform its task. Line 9 indicates that the constructor has a String param-
eter called name . When you create a new Account object (as you'll see in Fig. 3.6), you'll pass
a person's name to the constructor, which will receive that name in the parameter name . The
constructor will then assign name to instance variable name in line 11.

Error-Prevention Tip 3.2
Even though it's possible to do so, do not call methods from constructors. We'll explain this
in Chapter 10, Object-Oriented Programming: Polymorphism and Interfaces.

Parameter name of Class Account 's Constructor and Method setName
Recall from Section 3.2.1 that method parameters are local variables. In Fig. 3.5, the con-
structor and method setName both have a parameter called name . Although these param-
eters have the same identifier ( name ), the parameter in line 9 is a local variable of the
constructor that's not visible to method setName , and the one in line 15 is a local variable
of setName that's not visible to the constructor.

3.4.2 Class AccountTest : Initializing Account Objects When They're
Created
The AccountTest program (Fig. 3.6) initializes two Account objects using the construc-
tor. Line 10 creates and initializes the Account object account1 . Keyword new requests