数组初始化

基本类型与引用类型初始化区别，与全局参数初始化现象一致。

基本类型：初始化后赋予默认值，可直接使用

引用类型：初始化后引用为null，使用报错

package com.yjq.cn.initialize;import java.util.Arrays;import java.util.Random;/** * 基本类型，引用类型初始化区别 * */public class ArrayInitial {public static void main(String[] args) {Random rand = new Random(47);int[] a = new int[rand.nextInt(20)];System.out.println("length of a[basicType] = " + a.length);System.out.println(Arrays.toString(a));System.out.println("a[0]=" + a[0]);System.out.println("------------------");Integer[] b = new Integer[rand.nextInt(20)];System.out.println("length of b[quoteType] = " + b.length);System.out.println(Arrays.toString(b));System.out.println("b[0]=" + b[0]);}}

//output

length of a[basicType] = 18
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
------------------
length of b[quoteType] = 15
[null, null, null, null, null, null, null, null, null, null, null, null, null, null, null]