// references/Immutable1.java

// (c)2016 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://mindviewinc.com/Books/OnJava/ for more book information.

// Immutable objects are immune to aliasing

public class Immutable1 {

private int data;

public Immutable1(int initVal) {

data = initVal;

}

public int read() { return data; }

public boolean nonzero() { return data != 0; }

public Immutable1 multiply(int multiplier) {

return new Immutable1(data * multiplier);

}

public static void f(Immutable1 i1) {

Immutable1 quad = i1.multiply(4);

System.out.println("i1 = " + i1.read());

System.out.println("quad = " + quad.read());

}

public static void main(String[] args) {

Immutable1 x = new Immutable1(47);

System.out.println("x = " + x.read());

f(x);

System.out.println("x = " + x.read());

}

}

/* Output:

x = 47

i1 = 47

quad = 188

x = 47

*/