简单JAVA编程题

1. 编写一个程序，打印输出"Hello, World!"。

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

2. 编写一个程序，计算并打印两个整数的和。

public class Sum {
    public static void main(String[] args) {
        int num1 = 10;
        int num2 = 20;
        int sum = num1 + num2;
        System.out.println("Sum: " + sum);
    }
}

3. 编写一个程序，判断一个整数是否为偶数。

public class EvenNumber {
    public static void main(String[] args) {
        int num = 10;
        if (num % 2 == 0) {
            System.out.println(num + " is even.");
        } else {
            System.out.println(num + " is odd.");
        }
    }
}

4. 编写一个程序，计算并打印1到10之间所有整数的平方。

public class SquareNumbers {
    public static void main(String[] args) {
        for (int i = 1; i <= 10; i++) {
            int square = i * i;
            System.out.println(square);
        }
    }
}

5. 编写一个程序，计算并打印1到n之间所有整数的和，其中n是用户输入的值。

import java.util.Scanner;

public class SumOfNumbers {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter a number: ");
        int n = scanner.nextInt();
        int sum = 0;
        for (int i = 1; i <= n; i++) {
            sum += i;
        }
        System.out.println("Sum: " + sum);
    }
}

6.编写一个程序，找出一个整数数组中的最大值和最小值。

public class MaxMinValue {
    public static void main(String[] args) {
        int[] numbers = {10, 5, 8, 15, 3};
        int max = numbers[0];
        int min = numbers[0];

        for (int i = 1; i < numbers.length; i++) {
            if (numbers[i] > max) {
                max = numbers[i];
            }
            if (numbers[i] < min) {
                min = numbers[i];
            }
        }

        System.out.println("Max value: " + max);
        System.out.println("Min value: " + min);
    }
}

7.编写一个程序，判断一个字符串是否为回文字符串（正着读和反着读都一样）。

public class Palindrome {
    public static void main(String[] args) {
        String str = "level";
        boolean isPalindrome = true;

        for (int i = 0; i < str.length() / 2; i++) {
            if (str.charAt(i) != str.charAt(str.length() - 1 - i)) {
                isPalindrome = false;
                break;
            }
        }

        if (isPalindrome) {
            System.out.println(str + " is a palindrome.");
        } else {
            System.out.println(str + " is not a palindrome.");
8.       }
    }
}编写一个程序，将一个字符串中的所有单词颠倒顺序。

public class ReverseWords {
    public static void main(String[] args) {
        String str = "Hello World";
        String[] words = str.split(" ");
        String reversedStr = "";

        for (int i = words.length - 1; i >= 0; i--) {
            reversedStr += words[i] + " ";
        }

        System.out.println("Reversed string: " + reversedStr.trim());
    }
}

8.编写一个程序，计算并打印斐波那契数列的前n个数，其中n是用户输入的值。

import java.util.Scanner;

public class FibonacciSeries {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter the number of terms: ");
        int n = scanner.nextInt();

        int num1 = 0;
        int num2 = 1;

        System.out.print("Fibonacci series: " + num1 + " " + num2 + " ");

        for (int i = 3; i <= n; i++) {
            int sum = num1 + num2;
            System.out.print(sum + " ");
            num1 = num2;
            num2 = sum;
        }
    }
}