【Java-简单练习题】

1.”AABBBCCC“>>"A2B3C3"

public class Test6 {public static void main(String[] args) {String ns = "AABBBCCCC";String ret=compress(ns);System.out.println(ret);}public static String compress(String str) {StringBuilder ret = new StringBuilder();int count = 1;// 遍历至倒数第二个for (int i = 0; i < str.length()-1; i++) {if (str.charAt(i) == str.charAt(i + 1)) {count++;} else {ret.append(str.charAt(i)+""+count);count=1;}}//处理最后一个字符ret.append(str.charAt(str.length()-1)+""+count);return ret.toString();
}
}

2. 图书ISBN验证码

package ti;
import java.util.Scanner;
public class Test02 {public static void main(String[] args) {Scanner scan = new Scanner(System.in);//在此输入您的代码...//输入ISBNString isbn=scan.next();//去除分隔符String isbn1=isbn.replace("-","");//累加int sum=0;for(int i=0,k=1;i<isbn1.length()-1;i++,k++){int na=Integer.parseInt(String.valueOf(isbn1.charAt(i)));sum=sum+na*k;}//计算校验码String code=String.valueOf(sum%11==10?"X":sum%11);//判断String isbncode=String.valueOf(isbn.charAt(isbn.length()-1));if(code.equals(isbncode)){System.out.println("Right");}else{System.out.println(isbn.substring(0,isbn.length()-1)+code);}scan.close();}}

3. 统计字母数字中文符号的个数

public static void main(String[] args) {String str = "OMG,你们的中英混搭真是各有千秋,666但Someone丝毫掩盖不了你们那硬朗的英语底子！For eg.papi酱真的very有才华啊";HashMap<String, Integer> map = new HashMap<String, Integer>();map.put("letters", 0);//map.put("numbers", 0);map.put("chinese", 0);map.put("flags", 0);// 遍历字符串for (int i = 0; i < str.length(); i++) {char c = str.charAt(i);if (c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z') {int oldValue = map.get("letters");int newValue = oldValue + 1;map.put("letters", newValue);}if(c >= '0' && c <= '9') {map.put("numbers", map.getOrDefault("numbers",0)+1);}if(c >= 0x4e00 && c <= 0x29fa5) {map.put("chinese", map.get("chinese")+1);}else {map.put("flags", map.get("flags")+1);}}System.out.println(map);}

4. 幸运数字

package learn01;import java.math.BigInteger;public class Test02 {public static void main(String[] args) {int i = 1, counter = 0;while (true) {String bin = Integer.toBinaryString(i);String oct = Integer.toOctalString(i);String dec = String.valueOf(i);String hex = Integer.toHexString(i);int binsum = sum(bin, 2);int octsum = sum(oct, 8);int decsum = sum(dec, 10);int hexsum = sum(hex, 16);if (i % binsum == 0 && i % octsum == 0 && i % decsum == 0 && i % hexsum == 0) {System.out.println(i);counter++;}if(counter>=2023) {break;}i++;}}private static int sum(String number,int radix) {BigInteger ret=new BigInteger("0",radix);for(int i=0;i<number.length();i++) {BigInteger bn=new BigInteger(number.substring(i,i+1),radix);ret=ret.add(bn);}return ret.intValue();}
}