一维数组&三维数组

写一段程序来阐述数组简单的应用

package com.liaojianya.chapter1;

import java.util.Random;

/**
 * This program demonstrates the use of array.
 * @author LIAO JIANYA
 * 2016年7月20日
 */
public class ArrayAssignment8_3
{
	public static void main(String[] args)
	{
		Random rand = new Random();
		int[] a = null;
		int[] b = null;
		a = new int[rand.nextInt(10) + 1];
		b = a;
		
		System.out.println("the length of array_a : " + a.length);
		System.out.println("the length of array_b : " + b.length + "\n");
		
		for(int i = 0; i < a.length; i++)
		{
			a[i] = rand.nextInt(100);
			System.out.print("a[" + i + "] = " + a[i] + "\t");
			System.out.println("b[" + i + "] = " + b[i]);
		}
		
		if(a.length == 1)
		{
			System.out.println("The array_a only has one element.\n"
					+ "So the max value of array_a is same as the min value!");
		}
		else
		{
			int max = a[0];
			int min = a[0];
			
			
			for(int i = 0; i < a.length; i++)
			{
				if(a[i] > max)
				{
					max = a[i];
				}
				
				else if(a[i] < min)
				{
					min = a[i];
				}
			}
			
			System.out.println("\nThe max value of array_a is : " + max);
			System.out.println("The min value of array_a is : " + min);
			
		}
		

	}
}

　　运行结果1：

the length of array_a : 1
the length of array_b : 1

a[0] = 70	b[0] = 70
The array_a only has one element.
So the max value of array_a is same as the min value!

　　运行结果2：

the length of array_a : 7
the length of array_b : 7

a[0] = 39	b[0] = 39
a[1] = 90	b[1] = 90
a[2] = 49	b[2] = 49
a[3] = 35	b[3] = 35
a[4] = 33	b[4] = 33
a[5] = 12	b[5] = 12
a[6] = 75	b[6] = 75

The max value of array_a is : 90
The min value of array_a is : 12

　　分析：

　　1）代码行：b = a；表示将a数组的引用赋值给数组b，这时a和b是指向同一个数组对象。即“一个数组，两个名字”

　　2）创建一个Random类型的对象rand，此对象可以灵活的产生随机数，代码行a = new int[rand.nextInt(10)+1]; 在rand.nextInt（）后加1，可以避免出现0个元素数组。

若不加1，若随机到0，则会显示：

the length of array_a : 0
Exception in thread "main" the length of array_b : 0

java.lang.ArrayIndexOutOfBoundsException: 0
	at com.liaojianya.chapter1.ArrayAssignment8_3.main(ArrayAssignment8_3.java:30)

　　3）将变量min与max初值设为数组的第一个元素后，再逐一的与数组中的各元素相比，比min小的就将该元素值赋给min存放，使得min中的值始终保持最小；同理，当该元素大于max时，就将该元素赋给max存放，使得max的值保持最大。

编写多维数组使用方法的程序如下：

package com.liaojianya.chapter1;
/**
 * This program demonstrates the use of multiple array.
 * @author LIAO JIANYA
 * 2016年7月20日
 */
public class ThreeDimensionArray
{
	public static void main(String[] args)
	{
		int sum = 0;
		int[][][] a =  
			{
					{{5, 1}, {6, 7}},
					{{9, 4}, {8, 3}}
			};
		for(int i = 0; i < a.length; i++)
		{
			for(int j = 0; j < a[i].length; j++)
			{
				for(int k = 0; k < a[j].length; k++)
				{
					System.out.print("a[" + i + "][" + j + "][" + k + "] = " + a[i][j][k] + "\n");
					sum += a[i][j][k];
				}
			}
		}
		
		System.out.println("sum = " + sum);
	}

}

　　运行结果：

a[0][0][0] = 5
a[0][0][1] = 1
a[0][1][0] = 6
a[0][1][1] = 7
a[1][0][0] = 9
a[1][0][1] = 4
a[1][1][0] = 8
a[1][1][1] = 3
sum = 43