java string

package com.pl;

import java.util.Arrays;
import java.util.HashSet;
import java.util.Random;
import java.util.Set;
import java.util.regex.Pattern;

public class css_5 {
    public static void main(String[] args) {
        //m1();
        StringBuilder sbu = new StringBuilder();
        sbu.append("hello");
        sbu.append(18);
        sbu.insert(1, "Welcome - ");
//sbu.append("Welcome - ");
//sbu.append("Welcome - ",0,"Welcome - ".length());
        System.out.println(sbu);
        System.out.println(sbu.toString().concat("java"));
        sbu.delete(0, 5);
        System.out.println(sbu);


//错误的
//String s = sbu;
//String 转换为 StringBuilder
        String s1 = "hello";
        StringBuilder ss1 = new StringBuilder(s1);
        System.out.println(s1);
        System.out.println(ss1);
        System.out.println(ss1.toString());
        System.out.println(ss1.reverse().append("java.18").toString().toUpperCase());

        //StringBuilder 转换为 String
        String s2 = ss1.toString();
        System.out.println(s2);


        StringBuilder su1 = new StringBuilder();
        StringBuilder su2 = new StringBuilder(6);
        StringBuilder su3 = new StringBuilder("hello");
        System.out.println(su1);
        System.out.println(su1.length());
        System.out.println(su2);
        System.out.println(su2.length());
        System.out.println(su3);
        System.out.println(su3.length());
        StringBuffer suf1 = new StringBuffer();
        StringBuffer suf2 = new StringBuffer(6);
        StringBuffer suf3 = new StringBuffer("hello");
        System.out.println(suf1);
        System.out.println(suf1.length());
        System.out.println(suf2);
        System.out.println(suf2.length());
        System.out.println(suf3);
        System.out.println(suf3.length());


        System.out.printf("\n=========================================");
        String str = "hello16java16mysql8html";
        System.out.println(str);
//删除指定的数字
        System.out.println(str.replace("6", ""));
//删除所有数字
        for (int i = 0; i <= 9; i++) {
            str = str.replace(String.valueOf(i), "");
        }
        System.out.println(str);
//------------使用正则表达式，删除所有数字
        String str2 = "hello16789java16mysql8html";
        System.out.println(str2);
//hello16java16mysql8html
//这两个方法，支持正则表达式 \\d 代表数字 \\D 代表非数字
//String.replaceAll() String.replaceFirst();
        System.out.println(str2.replaceAll("\\d", ""));//删除字符串数字内容
//hellojavamysqlhtml
        System.out.println(str2.replaceAll("\\D", ""));//删除不是数字的内容
//16168
//删除首次出现的字符串匹配删除 \\d+
        System.out.println(str2.replaceFirst("\\d+", ""));
        String[] langs = str2.split("\\d+");
        System.out.println(Arrays.toString(langs));

//        String 支持正则表达式方法
//        .replaceAll()
//        .replaceFirst()
//        .split()
//        .matches()
        System.out.printf("\n=========================================");
        //判断字符串有没有大写
        String strx = "hello";
//.*[A-Z].*
// .代表一个任意符号
        if (strx.matches("^.*[A-Z].*$")) {
            System.out.println(String.format("%s:有大写字母", strx));
        } else {
            System.err.println(String.format("%s:没有大写字母", strx));
        }

        // 判断字符串有没有数字
        System.out.println("hello".matches("^.*\\d.*$"));
        //判断有没有汉字
        System.out.println("china".matches("^.*[\u4e00-\u9fa5].*$"));
// 判断是不是手机号
        String phone = "13014577066";
        String pattern = "^1[3,5,8]\\d{9}$";
        if (phone.matches(pattern)) {
            System.out.println("yes");
        } else {
            System.out.printf("手机号：%s不是合法的手机号。 \n", phone);
        }
// 判断是不是纯中文
        String name = "jack";
        String p = "^[\u4e00-\u9fa5]+$";
        if (name.matches(p)) {
            System.out.println(name);
        } else {
            System.out.println("姓名必须为纯中文");
        }
        String strv = "他的手机号是：13014577033，他在郑州。";
        System.out.println(strv.matches(".*\\d.*"));
//判断str是不是标准的手机号格式
        System.out.println(strv.matches("1[358]\\d{9}"));
//判断字符串有没有手机号
        System.out.println(strv.matches(".*1[358]\\d{9}.*"));
//是不是中文是不是一个汉字 ^开头 $代表结尾 {1}
        System.out.println("中文".matches("^[\u4e00-\u9fa5]$"));//false
//+ {1,}
        System.out.println("中文".matches("^[\u4e00-\u9fa5]+$"));//true
        System.out.println("中文".matches("[\u4e00-\u9fa5]+"));//true
        System.out.println("--".repeat(20));
//* 代表是 {0,}
        System.out.println("中文a".matches("[\u4e00-\u9fa5]*"));//false
        System.out.println("".matches("[\u4e00-\u9fa5]*"));//true
// ? {0,1}
        System.out.println("中".matches("[\u4e00-\u9fa5]?"));//true
        System.out.println("中文".matches("[\u4e00-\u9fa5]{2,6}"));//true
        System.out.println("**".repeat(25));
//是不是全英文
        System.out.println("abc".matches("[a-zA-Z]+"));//true
        System.out.println("ab c".matches("[a-zA-Z]+"));//false
        System.out.println("ab123c".matches("[a-zA-Z]+"));//false
        System.out.println("abDDDc".matches("[a-zA-Z]{1,}"));//true
        System.out.println("___".repeat(20));
//是不是全数字 "\\d+" "\\d*"
        System.out.println("0000".matches("\\d"));//false
        System.out.println("0000".matches("\\d+"));//true
        System.out.println("0000".matches("\\d?"));//false
        System.out.println("0000".matches("\\d*"));//true


//        for (int i = 0; i < sbu.length(); i++) {
//            System.out.printf("\n=======" + sbu[i]);
//
//        }
        System.out.printf("\n=========================================");
        //java.util.regex.Pattern
//var p1 = Pattern.compile("\\d");
        var p1 = Pattern.compile("[a-z]{1,}");
//var p2 = Pattern.compile("[a-zA-Z]{1,}");
        var p2 = Pattern.compile("[a-z]{1,}", Pattern.CASE_INSENSITIVE);
//var p2 = Pattern.compile("[a-z]{1,}", 2);
//输出正则表达式，字符串
//System.out.println(p1);
//System.out.println(p1.toString());
//System.out.println(p1.pattern());
//java.util.regex.Matcher
        var matcher = p2.matcher("java123mysql8html5javascriptcn.webrx.Book-student");
        while (matcher.find()) {
            System.out.printf("%s%n", matcher.group());
        }
//123456789
//12+3+4+56-7-8-9 = 100
        Set<String> set = new HashSet<String>();
        int index = 0;
        while (true) {
            String[] s1x = {"", "+", "-"};
            Random rand = new Random();
            StringBuilder sbux = new StringBuilder("1");
            for (int i = 2; i <= 9; i++) {
                sbux.append(s1x[rand.nextInt(s1x.length)]);
                sbux.append(i);
            }
//System.out.printf("%s%n", sbu);
            //[+-]?\\d+
            var p3 = Pattern.compile("[+-]*[0-9]+");
            var m3 = p3.matcher(sbu);
            int sum = 0;
            while (m3.find()) {
                int num = Integer.parseInt(m3.group());
                sum += num;
            }
            if (sum == 100 && !set.contains(sbu.toString())) {
                System.out.printf("%d、%s = 100%n", ++index, sbu);
                set.add(sbu.toString());
            }
            if (set.size() == 11) {
                break;
            }
        }
        for (String s : set) {
            System.out.printf("%s = 100%n", s);
        }


    }
}