一维数组&三维数组

矫情吗；* 2024-02-17 17:47 81阅读 0赞

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