智能医学工程-计算机程序设计-2025版-教学案例-第07章

eg 7.1.2

public class ArrayExample {
    public static void main(String[] args) {
        int[] numbers = new int[5]; // 声明一个长度为5的整数数组
        numbers[0] = 10; // 初始化数组元素
        numbers[1] = 20;
        System.out.println("第一个元素: " + numbers[0]); // 输出第一个元素
    }
}

eg 7.1.3

public class ArrayOperations {
    public static void main(String[] args) {
        int[] numbers = {1, 2, 3, 4, 5}; // 初始化数组
        for (int i = 0; i < numbers.length; i++) {
            System.out.println("元素 " + i + ": " + numbers[i]); // 遍历数组
        }
    }
}

eg 7.2.1

public class ArrayAlgorithms {
    public static void main(String[] args) {
        int[] numbers = {10, 20, 30, 40, 50};
        int sum = 0;
        int max = numbers[0];
        int min = numbers[0];
        
        for (int num : numbers) {
            sum += num;
            if (num > max) max = num;
            if (num < min) min = num;
        }
        
        double average = (double) sum / numbers.length;
        System.out.println("平均值: " + average);
        System.out.println("最大值: " + max);
        System.out.println("最小值: " + min);
    }
}

eg 7.2.3

import java.util.Arrays;

public class ArrayCopy {
    public static void main(String[] args) {
        int[] original = {1, 2, 3, 4, 5};
        int[] copy = new int[original.length];
        
        System.arraycopy(original, 0, copy, 0, original.length);
        
        System.out.println("原始数组: " + Arrays.toString(original));
        System.out.println("复制数组: " + Arrays.toString(copy));
    }
}

eg 7.3.1

public class TwoDimensionalArray {
    public static void main(String[] args) {
        int[][] matrix = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };
        
        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0; j < matrix[i].length; j++) {
                System.out.print(matrix[i][j] + " ");
            }
            System.out.println();
        }
    }
}

eg 7.3.2

public class IrregularArray {
    public static void main(String[] args) {
        int[][] irregularArray = {
                {1, 2},
                {3, 4, 5},
                {6}
        };
        
        for (int i = 0; i < irregularArray.length; i++) {
            for (int j = 0; j < irregularArray[i].length; j++) {
                final int k = irregularArray[i][j];
                System.out.print(k + " ");
            }
            System.out.println();
        }
        
        System.out.println();
        for (int i = 0; i < irregularArray.length; i++) {
            for (int j = 0; j < irregularArray[i].length; j++) {
                final int k = irregularArray[i][j];
                System.out.print(k + " ");
                if(k%2 == 0){
                    System.out.println("偶数");
                }else{
                    System.out.println("奇数");
                }
            }
            System.out.println();
        }
    }
}

eg 7.4.1

public class StringDemo {
    public static void main(String[] args) {
        String greeting = "Hello, World!";
        
        System.out.println(greeting);
        String anotherString = "Java is " + "awesome";
        System.out.println(anotherString);
        System.out.println(greeting.toUpperCase());
        
        String name = "Alice";
        String message = "Hello, " + name + "!";
        System.out.println(message);
    }
}

eg 7.4.2

public class StringOperations {
    public static void main(String[] args) {
        String text = "Java Programming";
        
        System.out.println("长度: " + text.length());
        System.out.println("字符 at 5: " + text.charAt(5));
        System.out.println("子字符串: " + text.substring(5, 11));
        System.out.println("位置: " + text.indexOf("Programming"));
        System.out.println("替换: " + text.replace("Java", "Python"));
        System.out.println("分割: " + Arrays.toString(text.split(" ")));
    }
}

eg 7.4.3

public class StringModification {
    public static void main(String[] args) {
        String str = "Hello";
        str = str.concat(" World"); // 创建新字符串
        System.out.println(str); // 输出: Hello World
    }
}

eg7Stream

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;

public class CollectionSortExample {
    public static void main(String[] args) {
        List<String> list = Arrays.asList("banana", "apple", "cherry", "date");
        
        List<String> sortedList = list.stream()
                                      .sorted()
                                      .collect(Collectors.toList());
        
        List<String> sortedByLengthDesc = list.stream()
                                              .sorted(Comparator.comparingInt(String::length).reversed())
                                              .collect(Collectors.toList());
        
        System.out.println(sortedList);
        System.out.println(sortedByLengthDesc);
    }
}