第二次作业（个人项目实践）

1. 设计一个类（不妨叫做A ），实现对一维数组(a[100])的指定范围内的元素相加运算。

package sijue;
import java.util.Scanner;//用于从键盘导入数据

public class A {
    public static void main(String[]args){   
        int[] list={-2574,-4010,8243,771,2447,-5197,2556,8044,3314,3617,6065,-2817,3131,6318,2186,-113,629,-2582,-37,-1520,164,2055,-5936,5912,1717,5988,4781,5757,892,-4394,8034,2213,-1080,-2080,5364,106,2657,566,3940,-5116,4583,1806,6555,2621,-7197,528,1626,18,1049,6243,3198,4397,-1325,9087,936,-6291,662,-178,135,-3473,-2385,-165,1713,-7949,-4234,1138,2212,104,6968,-3632,3801,1137,-1296,-1215,4272,6223,-5922,-7723,7044,-2938,-8180,1356,1159,-4022,-3713,1158,-8715,-4081,-2541,-2555,-2284,461,940,6604,-3631,3802,-2037,-4354,-1213,767};
        int sum=0;//存放和
        Scanner a= new Scanner(System.in) ;//Scanner类的对象a用来接收来自键盘的数据
        System.out.println("请输入起点：");
        int x=a.nextInt();
        System.out.println("请输入终点：");
        int y=a.nextInt();
        System.out.println("从"+x+"到"+y+"的和为");
        for(int i=x;i<=y;i++)
        sum+=list[i]; //循环                            
        System.out.println(sum); 
              }     
         }

运行结果：

2. 设计一个类（不妨叫做B ），实现对二维数组(a[N][M])的指定范围内的元素相加运算。

package sijue;
import java.util.Scanner;
public class B {
     public static void main(String[]args){
            int[][] a={{-2574,-4010,8243,771,2447,-5197,2556,8044,3314,3617,6065,-2817,3131,6318,2186,-113,629,-2582,-37,-1520,164,2055,-5936,5912,1717,5988,4781,5757,892,-4394,8034,2213,-1080,-2080,5364,106,2657,566,3940,-5116,4583,1806,6555,2621,-7197,528,1626,18,1049,6243,3198,4397,-1325,9087,936,-6291,662,-178,135,-3473,-2385,-165,1713,-7949,-4234,1138,2212,104,6968,-3632,3801,1137,-1296,-1215,4272,6223,-5922,-7723,7044,-2938,-8180,1356,1159,-4022,-3713,1158,-8715,-4081,-2541,-2555,-2284,461,940,6604,-3631,3802,-2037,-4354,-1213,767},{2740,-4182,-5632,-2966,-1953,567,-8570,1046,2211,1572,-2503,-1899,3183,-6187,3330,3492,-464,-2104,316,8136,470,50,466,-1424,5809,2131,6418,-3018,6002,-8379,1433,1144,2124,1624,-602,-5518,5872,870,-5175,-3961,-427,-6284,2850,481,6175,141,-766,-1897,-748,-4248,366,4823,3003,1778,3256,2182,2253,5076,5540,-2650,2451,-1875,5482,-6881,-329,-969,-8032,-2093,612,1524,-5492,5758,-7401,-5039,3241,6338,3581,4321,-1072,4942,2131,210,-7045,-7514,7450,-1142,-2666,-4485,-639,2121,-5298,-3805,-1686,-2520,-1680,2321,-4617,-1961,2076,7309}};
            int sum=0;
            Scanner b = new Scanner(System.in);
            System.out.println("起始行：");
            int x1 = b.nextInt(); 
            System.out.println("终点行");//x取值为1-2
            int y1 =b.nextInt();
            System.out.println("起始列：");
            int x2 = b.nextInt(); 
            System.out.println("终点列：");//y取值为1-100
            int y2 =b.nextInt();
            System.out.println("从("+x1+","+x2+")到"+"("+y1+","+y2+")的和为");
            for(int i=x1-1;i<=y1-1;i++)
            {
                for(int j=x2-1;j<=y2-1;j++)
                {
                sum+=a[i][j];
                }
            }
            System.out.println(sum);  
        }
    }

运行结果：

3. 设计一个类（不妨叫做C ），实现对三维数组的指定范围内的元素相加运算。

package sijue;
import java.util.Scanner;
public class C {
    public static void main(String[]args){
        int sum=0;
        int[][][] a= new int[][][]
           {
              {{-2574,-4010,8243,771,2447,-5197,2556,8044,3314,3617,6065,-2817,3131,6318,2186,-113,629,-2582,-37,-1520,164,2055,-5936,5912,1717,5988,4781,5757,892,-4394,8034,2213,-1080,-2080,5364,106,2657,566,3940,-5116,4583,1806,6555,2621,-7197,528,1626,18,1049,6243,3198,4397,-1325,9087,936,-6291,662,-178,135,-3473,-2385,-165,1713,-7949,-4234,1138,2212,104,6968,-3632,3801,1137,-1296,-1215,4272,6223,-5922,-7723,7044,-2938,-8180,1356,1159,-4022,-3713,1158,-8715,-4081,-2541,-2555,-2284,461,940,6604,-3631,3802,-2037,-4354,-1213,767}},
              {{2740,-4182,-5632,-2966,-1953,567,-8570,1046,2211,1572,-2503,-1899,3183,-6187,3330,3492,-464,-2104,316,8136,470,50,466,-1424,5809,2131,6418,-3018,6002,-8379,1433,1144,2124,1624,-602,-5518,5872,870,-5175,-3961,-427,-6284,2850,481,6175,141,-766,-1897,-748,-4248,366,4823,3003,1778,3256,2182,2253,5076,5540,-2650,2451,-1875,5482,-6881,-329,-969,-8032,-2093,612,1524,-5492,5758,-7401,-5039,3241,6338,3581,4321,-1072,4942,2131,210,-7045,-7514,7450,-1142,-2666,-4485,-639,2121,-5298,-3805,-1686,-2520,-1680,2321,-4617,-1961,2076,7309}},
              {{302,-7944,-6551,6648,-884,-6332,1188,-248,3902,-2171,-3782,-3510,6203,-636,-4605,4497,3187,-6278,1198,-7963,7647,-3022,-8267,7995,-1998,-4171,730,-8117,-1706,7601,-2454,-6161,-1810,243,-2841,-5377,2985,2328,177,5622,3596,3057,2830,-1151,6566,2254,6972,-3060,4063,367,84,3156,3880,-1530,5272,1385,-565,-1736,1267,-3863,-229,2072,2423,-7449,9555,2844,-1278,-3613,-919,4153,-4232,4032,-5732,199,4792,2498,-3344,-4193,2650,-579,3416,-3575,1822,-6936,-2661,-1873,414,2314,6844,7613,-7844,6680,5974,2208,-3597,6302,4396,-141,-1864,1939}}
             };
        Scanner c= new Scanner(System.in) ;
        System.out.println("x轴起点：");
        int x1 = c.nextInt() ;
        System.out.println("x轴终点：");//x取值为1-3
        int x2 =c.nextInt();
        System.out.println("y轴起点：");
        int y1 = c.nextInt() ;
        System.out.println("y轴终点：");//y取值为1
        int y2 =c.nextInt();
        System.out.println("z轴起点：");
        int z1 = c.nextInt() ;
        System.out.println("z轴终点：");//z取值为1-100
        int z2 =c.nextInt();
        System.out.println("从("+x1+","+y1+","+z1+")到"+"("+x2+","+y2+","+z2+")的和为:");
        for(int i=x1-1;i<=x2-1;i++)
        {
            for(int j=y1-1;j<=y2-1;j++)
            {
                for(int m=z1-1;m<=z2-1;m++)
                {
                sum+=a[i][j][m];
                }
            }
        }
        System.out.println(sum);
   }
}

运行结果：

小结：

    这次的作业完成的极其不顺利，在一开始老师布置作业的时候，我就有点懵，完全不懂老师让做什么，再加上本身变成并不拿手，这个作业也搁浅了相当久，但是在看到老师和助教在QQ群里的讲解后就恍然大悟了，也借鉴了同学的思想，比如说Scanner类的nextInt方法可从键盘导入数据，这个用法在学习Java的时候遇到过，然而我并没有记住并实践，所以这次也就只好“拿来主义”了。

   在运行二维数组的过程中，我遇到一个问题，如下图：

       这个问题让我百思不得其解，感觉莫名其妙，因为代码没有报错却没有运行结果，于是我就看了其他同学的随笔，发现问题出在了取值范围上，数据其实只有两行，每行有一百个，而我输入终点坐标的是（30，80），很明显是没有第三十行的，所是无法得出结果。

      做完这次实践，我更加明白了，同学之间合作的重要，还有遇到问题要及时询问老师，憋着不说是不可能有结果的，最后，一定要认真仔细，有时候一个符号都会影响结果。