廖雪峰Java9正则表达式-2正则表达式进阶-6搜索和替换

1.使用正则表达式分割字符串：

        String[] string.split(String regex);
        "a b c".split("\\s");->[a, b, c]
        "a b    c".split("\\s");->[a, b, , , , c]
        "a b    c".split("\\s+");->[a, b, c]
        "a,b:;c".split("[\\,\\:\\;\\s]+");->[a, b, c]

    public static void main(String[] args){
        String tags = "java php python";
        String[] arr = tags.split("\\s");
        System.out.println(Arrays.toString(arr));
    }

```#java
public class SplitString {
public static void main(String[] args){
String tags = "java php python";
String[] arr = tags.split("\\s+");
System.out.println(Arrays.toString(arr));
}
}
```

```#java
public class SplitString {
public static void main(String[] args){
String tags = "java, php;: python";
String[] arr = tags.split("[\\,\\;\\:\\s]+");
System.out.println(Arrays.toString(arr));
}
}
```

2.使用正则表达式查找字符串

package com.testList;

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

public class SearchString {
    public static void main(String[] args){
        String s = "The quick brown fox jumps over the lazy dog.";
        //区分大小写
        Pattern p1 = Pattern.compile("the");
        Matcher m1 = p1.matcher(s);
        while(m1.find()){
            String sub = s.substring(m1.start(),m1.end());
            System.out.print(sub+",start="+m1.start()+" end="+m1.end()+"\t");
        }
        System.out.println();
        //不区分大小写
        Pattern p2 = Pattern.compile("the",Pattern.CASE_INSENSITIVE);
        Matcher m2 = p2.matcher(s);
        while(m2.find()){
            String sub = s.substring(m2.start(),m2.end());
            System.out.print(sub+",start="+m2.start()+" end="+m2.end()+"\t");
        }
        System.out.println();
        //匹配每个单词
        Pattern p3 = Pattern.compile("\\w+",Pattern.CASE_INSENSITIVE);
        Matcher m3 = p3.matcher(s);
        while(m3.find()){
            String sub = s.substring(m3.start(),m3.end());
            System.out.print(sub+",start="+m3.start()+" end="+m3.end()+"\t");
        }
        System.out.println();
        //匹配带有o的单词
        Pattern p4 = Pattern.compile("\\w*o\\w*",Pattern.CASE_INSENSITIVE);
        Matcher m4 = p4.matcher(s);
        while(m4.find()){
            String sub = s.substring(m4.start(),m4.end());
            System.out.print(sub+",start="+m4.start()+" end="+m4.end()+"\t");
        }
    }
}

3.使用正则表达式替换字符串

public class SplitString {
    public static void main(String[] args){
        String s = "The  quick brown    fox jumps over   the  lazy dog.";
        //区分大小写
        String r = s.replaceAll("\\s+"," ");//参数依次为正则表达式，用于替换的字符
        System.out.println(r);
        String r2 = s.replaceAll("(\\w+)","<b>$1</b>");//$1方向引用，指向前面捕获的单词
        System.out.println(r2);
    }
}

4.总结

使用正则表达式可以：

• 分割字符串：String .split()
• 搜索字串：Matcher.find()
• 替换字符串：String.replaceAll()