java正则匹配和替换非数字、非字母

使用java的正则匹配之前要记得导包

import java.util.regex.Matcher;
import java.util.regex.Pattern;

1.使用正则判断是否有数字、字母

 public static void main(String[] args) {
        System.out.println(containsNum("111"));
        System.out.println(containsLetter("aaa"));
        System.out.println(containsNumOrLetter("aaa"));
    }
//判断是否含有字母
    public static boolean containsLetter(String str) {
        String patt="[a-z|A-Z]";
        Pattern r = Pattern.compile(patt);
        Matcher matcher = r.matcher(str);
        return matcher.find();
    }
//判断是否含有数字
    public static boolean containsNum(String str) {
        String patt="[0-9]";
        Pattern r = Pattern.compile(patt);
        Matcher matcher = r.matcher(str);
        return matcher.find();
    }
//判断是否含有数字或字母
    public static boolean containsNumOrLetter(String str) {
        String patt="[0-9|a-z|A-Z]";
        Pattern r = Pattern.compile(patt);
        Matcher matcher = r.matcher(str);
        return matcher.find();
    }

2.那如果是判断是不含有字母或数字的正则怎么写呢？

   public static void main(String[] args) {
        System.out.println(containsNoNum("111"));
        System.out.println(containsNoLetter("aaa"));
        System.out.println(containsNoNumOrLetter("aaa"));
    }

    public static boolean containsNoLetter(String str) {
        String patt="[^a-z]";
        Pattern r = Pattern.compile(patt);
        Matcher matcher = r.matcher(str);
        return matcher.find();
    }

    public static boolean containsNoNum(String str) {
        String patt="[^0-9]";
        Pattern r = Pattern.compile(patt);
        Matcher matcher = r.matcher(str);
        return matcher.find();
    }

    public static boolean containsNoNumOrLetter(String str) {
        String patt="[^0-9|a-z|A-Z]";
        Pattern r = Pattern.compile(patt);
        Matcher matcher = r.matcher(str);
        return matcher.find();
    }

3.根据上面的正则来写一个比较版本号的方法

    public static void main(String[] args) {
        System.out.println(compareVersion("1.3_bc", "1.3_b"));
    }


    public static String compareVersion(String version1, String version2) {

        //忽略大小写，只保留数字和字母和点
        String v1 = version1.toLowerCase().replaceAll("[^0-9|a-z|.]", "");
        String v2 = version2.toLowerCase().replaceAll("[^0-9|a-z|.]", "");
        //按点来切割
        String[] arr1 = v1.split("\\.");
        String[] arr2 = v2.split("\\.");
        int len = arr1.length > arr2.length ? arr2.length : arr1.length;

        //正则判断是否含有字母
        String patt = "[a-z]";
        Pattern r = Pattern.compile(patt);
        int i = 0;
        do {
            Matcher m1 = r.matcher(arr1[i]);
            Matcher m2 = r.matcher(arr2[i]);

            boolean flag = false;
            //判断是否含有字母
            if (m1.find() && m2.find()) {//如果都含有字母
                //先比较数字
                String num1 = arr1[i].substring(0, m1.start());
                String num2 = arr2[i].substring(0, m2.start());
                if (Integer.parseInt(num1) > Integer.parseInt(num2)) {
                    return version1;
                } else if (Integer.parseInt(num1) < Integer.parseInt(num2)) {
                    return version2;
                }
                //再比较含有字母的字符串
                String str1 = arr1[i].substring(m1.start());
                String str2 = arr2[i].substring(m2.start());
                if (str1.compareTo(str2) > 0)
                    return version1;
                else if (str1.compareTo(str2) < 0)
                    return version2;
            } else if ((flag = m1.find()) || m2.find()) {//如果只是其中一个含有字母
                String vContains = flag ? arr1[i] : arr2[i];
                String vOther = flag ? arr2[i] : arr1[i];
                //先比较数字
                String num1 = vContains.substring(0, flag ? m1.start() : m2.start());
                String num2 = vOther;
                if (Integer.parseInt(num1) > Integer.parseInt(num2)) {
                    return version1;
                } else if (Integer.parseInt(num1) < Integer.parseInt(num2)) {
                    return version2;
                }
                return flag ? version1 : version2;
            } else {//如果都不含有字母，则直接比较数字
                if (Integer.parseInt(arr1[i]) > Integer.parseInt(arr2[i])) {
                    return version1;
                } else if (Integer.parseInt(arr1[i]) < Integer.parseInt(arr2[i])) {
                    return version2;
                }
            }
        } while (++i < len);

        //以上判断都没有结果则返回数组 长度较长的那个版本
        return arr1.length > arr2.length ? version1 : version2;
    }

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