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C # tutorial
The meaning of Encapsulation, is to make sure that "sensitive" data is hidden from users. To achieve this, you must:
The meaning of Encapsulation, is to make sure that "sensitive" data is hidden from users. To achieve this, you must:
private
private
variableYou learned from the previous chapter that private
variables can only be
accessed within the same class (an outside class has no access to it). However,
it is possible to access them if we provide public get and set methods.
The get
method returns the variable value, and the set
method sets the value.
Syntax for both is that they start with either get
or set
, followed by the
name of the variable, with the first letter in upper case:
public class Person {
private String name; // private = restricted access
// Getter
public String getName() {
return name;
}
// Setter
public void setName(String newName) {
this.name = newName;
}
}
Example explained
The get
method returns the value of the variable name
.
The set
method takes a parameter (newName
) and assigns it to the
name
variable. The this
keyword is used to refer to the current
object.
However, as the name
variable is declared as private
, we
cannot access it from outside this class:
public class Main {
public static void main(String[] args) {
Person myObj = new Person();
myObj.name = "John"; // error
System.out.println(myObj.name); // error
}
}
If the variable was declared as public
, we would expect the following output:
John
However, as we try to access a private
variable, we get an error:
MyClass.java:4: error: name has private access in Person
myObj.name = "John";
^
MyClass.java:5: error: name has private access in Person
System.out.println(myObj.name);
^
2 errors
Instead, we use the getName()
and setName()
methods to access and update the variable:
public class Main {
public static void main(String[] args) {
Person myObj = new Person();
myObj.setName("John"); // Set the value of the name variable to "John"
System.out.println(myObj.getName());
}
}
// Outputs "John"
get
method), or write-only (if you only use the set
method)