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//: reusing/FinalData.java

// The effect of final on fields.

import java.util.*;

import static net.mindview.util.Print.*;

class Value {

int i; // Package access

public Value(int i) { this.i = i; }

}

public class FinalData {

private static Random rand = new Random(47);

private String id;

public FinalData(String id) { this.id = id; }

// Can be compile-time constants:

private final int valueOne = 9;

private static final int VALUE_TWO = 99;

// Typical public constant:

public static final int VALUE_THREE = 39;

// Cannot be compile-time constants:

private final int i4 = rand.nextInt(20);

static final int INT_5 = rand.nextInt(20);

private Value v1 = new Value(11);

private final Value v2 = new Value(22);

private static final Value VAL_3 = new Value(33);

// Arrays:

private final int[] a = { 1, 2, 3, 4, 5, 6 };

public String toString() {

return id + ": " + "i4 = " + i4 + ", INT_5 = " + INT_5;

}

public static void main(String[] args) {

FinalData fd1 = new FinalData("fd1");

//! fd1.valueOne++; // Error: can't change value

fd1.v2.i++; // Object isn't constant!

fd1.v1 = new Value(9); // OK -- not final

for(int i = 0; i < fd1.a.length; i++)

fd1.a[i]++; // Object isn't constant!

//! fd1.v2 = new Value(0); // Error: Can't

//! fd1.VAL_3 = new Value(1); // change reference

//! fd1.a = new int[3];

print(fd1);

print("Creating new FinalData");

FinalData fd2 = new FinalData("fd2");

print(fd1);

print(fd2);

}

} /* Output:

fd1: i4 = 15, INT_5 = 18

Creating new FinalData

fd1: i4 = 15, INT_5 = 18

fd2: i4 = 13, INT_5 = 18

*///:~