Regular expression matching, replacement, search, and cutting methods in JAVA-javaTutorial-php.cn

Regular expression matching, replacement, search, and cutting methods in JAVA

高洛峰

Release： 2017-01-22 13:53:45

Original

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正则表达式的查找;主要是用到String类中的split();

String str;

str.split();方法中传入按照什么规则截取,返回一个String数组

常见的截取规则:

str.split("\\.")按照.来截取

str.split(" ")按照空格截取

str.split("cc+")按照c字符来截取,2个c或以上

str.split((1)\\.+)按照字符串中含有2个字符或以上的地方截取(1)表示分组为1

截取的例子;

按照分组截取;截取的位置在两个或两个以上的地方

String str = "publicstaticccvoidddmain";
   //对表达式进分组重用
   String ragex1="(.)\\1+";
   String[] ss = str.split(ragex1);
   for(String st:ss){
   System.out.println(st);
   }
//按照两个cc+来截取
String ragex = " ";
  //切割
   String strs = "publicstaticccvoidddmain";
  String ragexs = "cc+";
  String[] s = strs.split(ragexs);
  for(String SSSS :s){
  System.out.println(SSSS);
  }
  System.out.println("=-=========");

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正则表达式中的替换;

语法定义规则;

String s =str.replaceAll(ragex, newstr);

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字符串中的替换是replace();

将4个或4个以上的连续的数字替换成*

// 替换
   String str="wei232123jin234";
   String ragex = "\\d{4,}";
   String newstr = "*";
   String s =str.replaceAll(ragex, newstr);
   System.out.println(s);

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将重复的字符串换成一个*

String str ="wwweiei222222jjjiiinnn1232";
   String ragex ="(.)\\1+";
   String newStr ="*";
   String s = str.replaceAll(ragex, newStr);
   System.out.println(s);

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将我...我...要..要.吃...吃...饭换成我要吃饭

String str = "我...我...要..要.吃...吃...饭";
  String regex = "\\.+";
  String newStr = "";
  str=test(str, regex, newStr);
  regex = "(.)\\1+";
  newStr = "$1";
  test(str, regex, newStr);
public static String test(String str, String regex, String newStr) {
  String str2 = str.replaceAll(regex, newStr);
  System.out.println(str2);
  return str2;
 }

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正则表达式的字符串的获取

1,根据定义的正则表达式创建Pattern对象

2,使用Pattern对象类匹配

3,判断是否为true

4,加入到组

例子;

String str = "public static void main(String[] args)"
    + " public static void main(String[] args)public static void main(String[] args)";
 String ragex = "\\b[a-zA-Z]{4,5}\\b";
 Pattern p =Pattern.compile(ragex);
 Matcher m = p.matcher(str);
    while(m.find()){
    String s = m.group();
    System.out.println(s);
    }

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作业:

1,获取user中的user

String str ="<html>user</html>";
String regex = "<html>|</html>";
 String newStr = "";
String str2 = str.replaceAll(regex, newStr);
System.out.println(str2);

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2,获取dhfjksaduirfn 11@qq.com dsjhkfa wang@163.com wokaz中的邮箱号码

String regex = " ";
String[] strs=str.split(regex);
 for(String str2:strs){
 String ragexDemo = "[a-zA-Z0-9]([a-zA-Z0-9]*[-_]?[a-zA-Z0-9]+)*"
 + "@([a-zA-Z0-9]+)\\.[a-zA-Z]+\\.?[a-zA-Z]{0,2}";
Pattern p = Pattern.compile(ragexDemo);
Matcher m = p.matcher(str2);
while(m.find()){
System.out.println(m.group());
  }
 }

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示例代码：

import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
public class test {
  public static void main(String[] args) {
    getStrings(); //用正则表达式获取指定字符串内容中的指定内容
    System.out.println("********************");
    replace(); //用正则表达式替换字符串内容
    System.out.println("********************");
    strSplit(); //使用正则表达式切割字符串
    System.out.println("********************");
    strMatch(); //字符串匹配
  }
 
  private static void strMatch() {
    String phone = "13539770000";
    //检查phone是否是合格的手机号(标准:1开头，第二位为3,5,8，后9位为任意数字)
    System.out.println(phone + ":" + phone.matches("1[358][0-9]{9,9}")); //true 
     
    String str = "abcd12345efghijklmn";
    //检查str中间是否包含12345
    System.out.println(str + ":" + str.matches("\\w+12345\\w+")); //true
    System.out.println(str + ":" + str.matches("\\w+123456\\w+")); //false
  }
 
  private static void strSplit() {
    String str = "asfasf.sdfsaf.sdfsdfas.asdfasfdasfd.wrqwrwqer.asfsafasf.safgfdgdsg";
    String[] strs = str.split("\\.");
    for (String s : strs){
      System.out.println(s);
    }   
  }
 
  private static void getStrings() {
    String str = "rrwerqq84461376qqasfdasdfrrwerqq84461377qqasfdasdaa654645aafrrwerqq84461378qqasfdaa654646aaasdfrrwerqq84461379qqasfdasdfrrwerqq84461376qqasfdasdf";
    Pattern p = Pattern.compile("qq(.*?)qq");
    Matcher m = p.matcher(str);
    ArrayList<String> strs = new ArrayList<String>();
    while (m.find()) {
      strs.add(m.group(1));     
    }
    for (String s : strs){
      System.out.println(s);
    }   
  }
 
  private static void replace() {
    String str = "asfas5fsaf5s4fs6af.sdaf.asf.wqre.qwr.fdsf.asf.asf.asf";
    //将字符串中的.替换成_，因为.是特殊字符，所以要用\.表达，又因为\是特殊字符，所以要用\\.来表达.
    str = str.replaceAll("\\.", "_");
    System.out.println(str);   
  }
}

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