With this example we are going to demonstrate how to initialize final fields of a class. In short, to initialize final fields of a class we have followed the below steps:
- We have created class
P, that has a private int attribute and overrides thetoString()method of Object to return the String representation of the int value. - We have also created a class,
BlankFinal, that consists of two private final int values,xinitialized to 0 andy, and a finalP. - It has a constructor where it initializes
yandP, and another constructor where it uses an intxand initializesyandPusing it. - We create a new instance of
BlankFinalusing the first constructor and then another instance using the second constructor.
Let’s take a look at the code snippet that follows:
package com.javacodegeeks.snippets.core;
class P {
private int i;
P(int i) {
this.i = i;
}
@Override
public String toString() {
return "[" + new Integer(this.i).toString() + "]";
}
}
public class BlankFinal {
private final int x = 0; // Initialized final
private final int y; // Blank final
private final P z; // Blank final reference
// Blank finals MUST be initialized in the constructor:
public BlankFinal() {
y = 1; // Initialize blank final
z = new P(1); // Initialize blank final reference
System.out.println("Initializing BlankFinal : y = " + this.y + ", z = " + this.z);
}
public BlankFinal(int x) {
y = x; // Initialize blank final
z = new P(x); // Initialize blank final reference
System.out.println("Initializing BlankFinal : y = " + this.y + ", z = " + this.z);
}
public static void main(String[] args) {
new BlankFinal();
new BlankFinal(47);
}
}
Output:
Initializing BlankFinal : y = 1, z = [1]
Initializing BlankFinal : y = 47, z = [47]
This was an example of how to initialize final fields of a class in Java.
