// arrays/ArrayOptions.java

// (c)2017 MindView LLC: see Copyright.txt

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

// Visit http://OnJava8.com for more book information.

// Initialization & re-assignment of arrays

import java.util.*;

import static onjava.ArrayShow.*;

public class ArrayOptions {

public static void main(String[] args) {

// Arrays of objects:

BerylliumSphere[] a; // Uninitialized local

BerylliumSphere[] b = new BerylliumSphere[5];

// The references inside the array are

// automatically initialized to null:

show("b", b);

BerylliumSphere[] c = new BerylliumSphere[4];

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

if(c[i] == null) // Can test for null reference

c[i] = new BerylliumSphere();

// Aggregate initialization:

BerylliumSphere[] d = {

new BerylliumSphere(),

new BerylliumSphere(),

new BerylliumSphere()

};

// Dynamic aggregate initialization:

a = new BerylliumSphere[]{

new BerylliumSphere(), new BerylliumSphere(),

};

// (Trailing comma is optional)

System.out.println("a.length = " + a.length);

System.out.println("b.length = " + b.length);

System.out.println("c.length = " + c.length);

System.out.println("d.length = " + d.length);

a = d;

System.out.println("a.length = " + a.length);

// Arrays of primitives:

int[] e; // Null reference

int[] f = new int[5];

// The primitives inside the array are

// automatically initialized to zero:

show("f", f);

int[] g = new int[4];

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

g[i] = i*i;

int[] h = { 11, 47, 93 };

// Compile error: variable e not initialized:

//- System.out.println("e.length = " + e.length);

System.out.println("f.length = " + f.length);

System.out.println("g.length = " + g.length);

System.out.println("h.length = " + h.length);

e = h;

System.out.println("e.length = " + e.length);

e = new int[]{ 1, 2 };

System.out.println("e.length = " + e.length);

}

}

/* Output:

b: [null, null, null, null, null]

a.length = 2

b.length = 5

c.length = 4

d.length = 3

a.length = 3

f: [0, 0, 0, 0, 0]

f.length = 5

g.length = 4

h.length = 3

e.length = 3

e.length = 2

*/