The only way you can access an object is through a reference variable. A reference variable is declared to be of a specific type and that type can never be changed. Reference variables can be declared as static variables, instance variables, method parameters, or local variables.
A reference variable that is declared as final can’t never be reassigned to refer to a different object. The data within the object can be modified, but the reference variable cannot be changed.
package org.kodejava.basic;
public class ReferenceDemo {
public static void main(String[] args) {
// Declaration of Reference variable
Reference ref1, ref2;
// ref3 is declared final, ref3 can't be reassigned
// or refer to different object
final Reference ref3;
// assign ref1 with object Reference
ref1 = new Reference("This is the first reference variable", 1);
// access method getNumber() of object Reference through
// variable ref1
int number = ref1.getNumber();
System.out.println("number= " + number);
// assign ref2 with object Reference
ref2 = new Reference("This is the second reference variable", 2);
// passing ref2 as method parameter of printText() method
ReferenceDemo.printText(ref2);
// assign ref3 with object Reference
ref3 = new Reference("This is the third reference variable", 3);
// try to reassign ref3 will cause a compile-time error
// ref3 = new Reference("Try to reassign", 3);
}
public static void printText(Reference reference) {
String text = reference.getText();
System.out.println(text);
}
}
package org.kodejava.basic;
public class Reference {
private int number;
private String text;
Reference(String text, int number) {
this.text = text;
this.number = number;
}
public String getText() {
return text;
}
public int getNumber() {
return number;
}
}
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