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Java练习题 (2024.7.23)

news 来源：原创 2024/9/20 7:51:29

Exercise1

package Exercise20240723;
import java.util.Scanner;
import java.util.ArrayList;
public class Exercise1 {public static void main(String[] args) {/* 需求：键盘录入一些1~10日之间的整数，并添加到集合中。直到集合中所有数据和超过200为止。 */Scanner sc = new Scanner(System.in);ArrayList<Integer> arrayList = new ArrayList<>();int result;while (true) {result = getSum(arrayList);if (result > 200) {System.out.println("已经超过两百，现在集合的和是" + result);break;}System.out.println("请输入1个整数");int number = sc.nextInt();if (rightNumber(number)) {arrayList.add(number);} else {System.out.println("整数不和规范，请重新输入");}}}public static boolean rightNumber(int number) {if (number >= 1 && number <= 100 ) {return true;}return false;}public static int getSum(ArrayList<Integer> arrayList) {int sum = 0;for (Integer i : arrayList) {sum += i;}return sum;}
}

Exercise2

package Exercise20240723;
import java.util.Scanner;
public class Exercise2 {public static void main(String[] args) {
//        需求：
//        自己实现parseInt方法的效果，将字符串形式的数据转成整数。
//        要求:字符串中只能是数字不能有其他字符最少一位，最多10位0不能开头Scanner sc = new Scanner(System.in);System.out.println("请输入一个字符串");String str = sc.nextLine();if (!str.matches("[1-9]\\d{0,9}")) {System.out.println("不合规的字符串");System.exit(1);}int number = 0;for (int i = 0; i < str.length(); i++) {number = number * 10 + (str.charAt(i) - '0');}System.out.println(number);System.out.println(number + 5);}
}

Exercise3

package Exercise20240723;
import java.util.Scanner;
public class Exercise3 {public static void main(String[] args) {
//        需求：
//        定义一个方法自己实现toBinaryString方法的效果，将一个十进制整数转成字符串表示的二进制Scanner sc = new Scanner(System.in);System.out.println("请输入一个整数");int number = sc.nextInt();String str = "";while (number > 0) {str = number % 2 + str;number /= 2;}System.out.println(str);}
}

Exercise4

package Exercise20240723;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.temporal.ChronoUnit;
import java.util.Scanner;
import java.util.Date;
public class Exercise4 {public static void main(String[] args) throws ParseException {
//        需求：
//        请使用代码实现计算你活了多少天，用JDK7和JDK8两种方式完成Scanner sc = new Scanner(System.in);// JDK7;System.out.println("请输入你的生日");String birthday = sc.nextLine();SimpleDateFormat birthdayFormat = new SimpleDateFormat("yyyy-MM-dd");Date birthdayDate = birthdayFormat.parse(birthday);Long birthdayTime = birthdayDate.getTime();System.out.println("已经活了" + ((System.currentTimeMillis() - birthdayTime) / 1000 / 3600 / 24) + "天");// JDK8LocalDate birthday8 = LocalDate.of(2004, 10, 14);LocalDate nowTime = LocalDate.now();long days = ChronoUnit.DAYS.between(birthday8, nowTime);System.out.println(days);}
}