Java实验报告三

 1 import java.util.Arrays;
 2 
 3 public class CopyArray {
 4     public static void main(String[] args) {
 5         int[] a = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
 6         int[] b = new int[a.length];
 7 
 8         // 将数组 a 中的所有元素拷贝到数组 b 中,用循环实现
 9         for (int i = 0; i < a.length; i++) {
10             b[i] = a[i];
11         }
12 
13         // 打印 b 中元素
14         System.out.println(Arrays.toString(b));
15 
16         // 将数组 a 中从第 3 个元素起连续 5 个元素拷贝到数组 b 中,用数组拷贝方法实现
17         int[] c = new int[5];
18         System.arraycopy(a, 2, c, 0, 5);
19 
20         // 打印 b 中的元素
21         System.out.println(Arrays.toString(c));
22     }
23 }

 1 import java.util.Arrays;
 2 
 3 public class UpSort {
 4     public static void main(String[] args) {
 5         int[] a = {5, 4, 9, 2, 7,12,-6};
 6 
 7         // 升序排列
 8         Arrays.sort(a);
 9         System.out.println("升序排列结果：" + Arrays.toString(a));
10 
11         // 降序排列
12         for (int i = 0; i < a.length / 2; i++) {
13             int temp = a[i];
14             a[i] = a[a.length - 1 - i];
15             a[a.length - 1 - i] = temp;
16         }
17         System.out.println("降序排列结果：" + Arrays.toString(a));
18     }
19 }

  1 public class Matrix {
  2     private int[][] data;
  3 
  4     public Matrix(int rows, int columns) {
  5         data = new int[rows][columns];
  6     }
  7 
  8     public Matrix(int[][] data) {
  9         this.data = data;
 10     }
 11 
 12     // 获取矩阵的行数
 13     public int getRowCount() {
 14         return data.length;
 15     }
 16 
 17     // 获取矩阵的列数
 18     public int getColumnCount() {
 19         return data[0].length;
 20     }
 21 
 22     // 获取矩阵中指定位置的元素
 23     public int get(int row, int column) {
 24         return data[row][column];
 25     }
 26 
 27     // 设置矩阵中指定位置的元素
 28     public void set(int row, int column, int value) {
 29         data[row][column] = value;
 30     }
 31 
 32     // 转置矩阵
 33     public Matrix transpose() {
 34         int rows = getRowCount();
 35         int columns = getColumnCount();
 36         Matrix result = new Matrix(columns, rows);
 37         for (int i = 0; i < rows; i++) {
 38             for (int j = 0; j < columns; j++) {
 39                 result.set(j, i, get(i, j));
 40             }
 41         }
 42         return result;
 43     }
 44 
 45     // 矩阵相加
 46     public Matrix add(Matrix other) {
 47         int rows = getRowCount();
 48         int columns = getColumnCount();
 49         Matrix result = new Matrix(rows, columns);
 50         for (int i = 0; i < rows; i++) {
 51             for (int j = 0; j < columns; j++) {
 52                 result.set(i, j, get(i, j) + other.get(i, j));
 53             }
 54         }
 55         return result;
 56     }
 57 
 58     // 按行优先存储，返回一维数组
 59     public int[] toRowArray() {
 60         int rows = getRowCount();
 61         int columns = getColumnCount();
 62         int[] result = new int[rows * columns];
 63         for (int i = 0; i < rows; i++) {
 64             for (int j = 0; j < columns; j++) {
 65                 result[i * columns + j] = get(i, j);
 66             }
 67         }
 68         return result;
 69     }
 70 
 71     // 按列优先存储，返回一维数组
 72     public int[] toColumnArray() {
 73         int rows = getRowCount();
 74         int columns = getColumnCount();
 75         int[] result = new int[rows * columns];
 76         for (int j = 0; j < columns; j++) {
 77             for (int i = 0; i < rows; i++) {
 78                 result[j * rows + i] = get(i, j);
 79             }
 80         }
 81         return result;
 82     }
 83 
 84     // 获取矩阵中的鞍点，如果没有鞍点则返回 null
 85     public int[] getSaddlePoint() {
 86         int rows = getRowCount();
 87         int columns = getColumnCount();
 88         for (int i = 0; i < rows; i++) {
 89             int minIndex = 0;
 90             int minValue = get(i, 0);
 91             for (int j = 1; j < columns; j++) {
 92                 if (get(i, j) < minValue) {
 93                     minIndex = j;
 94                     minValue = get(i, j);
 95                 }
 96             }
 97             boolean isSaddlePoint = true;
 98             for (int k = 0; k < rows; k++) {
 99                 if (get(k, minIndex) > minValue) {
100                     isSaddlePoint = false;
101                     break;
102                 }
103             }
104             if (isSaddlePoint) {
105                 return new int[]{i, minIndex};
106             }
107         }
108         return null;
109     }
110 
111     // 将矩阵转换为字符串形式，用于打印输出
112     @Override
113     public String toString() {
114         StringBuilder builder = new StringBuilder();
115         int rows = getRowCount();
116         int columns = getColumnCount();
117         for (int i = 0; i < rows; i++) {
118             for (int j = 0; j < columns; j++) {
119                 builder.append(get(i, j));
120                 builder.append(' ');
121             }
122             builder.append('\n');
123         }
124         return builder.toString();
125     }
126 }

 1 import java.util.Arrays;
 2 public class MatrixTest {
 3     public static void main(String[] args) {
 4         Matrix matrix = new Matrix(new int[][]{
 5                 {1, 2, 3},
 6                 {4, 5, 6},
 7                 {7, 8, 9},
 8         });
 9         System.out.println(matrix);
10         System.out.println("Transpose:");
11         System.out.println(matrix.transpose());
12         System.out.println("Add:");
13         System.out.println(matrix.add(new Matrix(new int[][]{
14                 {9, 8, 7},
15                 {6, 5, 4},
16                 {3, 2, 1},
17         })));
18         System.out.println("Row Array:");
19         System.out.println(Arrays.toString(matrix.toRowArray()));
20         System.out.println("Column Array:");
21         System.out.println(Arrays.toString(matrix.toColumnArray()));
22         System.out.println("Saddle Point:");
23         System.out.println(Arrays.toString(matrix.getSaddlePoint()));
24     }
25 }