Java 编程实例：相加数字、计算单词数、字符串反转、元素求和、矩形面积及奇偶判断

public class AddNumbers {
    public static void main(String[] args) {
        int num1 = 5, num2 = 10, sum;
        sum = num1 + num2;
        System.out.println("Sum of " + num1 + " and " + num2 + " is: " + sum);
    }
}

public class WordCount {
    public static void main(String[] args) {
        String sentence = "This is a sample sentence";
        String[] words = sentence.split("\\s+");
        int wordCount = words.length;
        System.out.println("Word count: " + wordCount);
    }
}

public class StringReverse {
    public static void main(String[] args) {
        String str = "Hello World";
        StringBuilder reversed = new StringBuilder();
        reversed.append(str);
        reversed = reversed.reverse();
        System.out.println("Reversed string: " + reversed);
    }
}

public class ArraySum {
    public static void main(String[] args) {
        int[] numbers = {1, 2, 3, 4, 5};
        int sum = 0;
        for (int num : numbers) {
            sum += num;
        }
        System.out.println("Sum of array elements: " + sum);
    }
}

public class RectangleArea {
    public static void main(String[] args) {
        int length = 5;
        int width = 10;
        int area = length * width;
        System.out.println("Area of rectangle: " + area);
    }
}

public class OddEven {
    public static void main(String[] args) {
        int num = 5;
        if (num % 2 == 0) {
            System.out.println(num + " is even.");
        } else {
            System.out.println(num + " is odd.");
        }
    }
}