Java正则表达式逻辑运算符
Java正则表达式支持3个逻辑运算符，它们是-
XY：X，然后是Y
X|Y：X或Y
(X)：捕获组。
XY：X，然后是Y
这仅匹配两个连续的单个字符。
示例
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Test {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter input text: ");
String input = sc.nextLine();
String regex = "am";
//创建一个模式对象
Pattern pattern = Pattern.compile(regex);
//匹配字符串中的已编译模式
Matcher matcher = pattern.matcher(input);
if (matcher.find()) {
System.out.println("Match occurred");
} else {
System.out.println("Match not occurred");
}
}
}输出1
Enter input text: sample text Match occurred
输出2
Enter input text: hello how are you Match not occurred
X|Y
这匹配“|”周围的两个表达式/字符中的任何一个
示例
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexExample {
public static void main( String args[] ) {
String regex = "Hello|welcome";
String input = "Hello how are you welcome to Nhooo";
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(input);
int count = 0;
while(matcher.find()) {
count++;
}
System.out.println("Number of matches: "+count);
}
}输出结果
Number of matches: 2
(X)：捕获组
捕获组使您可以将多个字符视为一个单元。您只需要将这些字符放在一组括号内即可。
示例
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class CapturingGroups {
public static void main( String args[] ) {
System.out.println("Enter input text");
Scanner sc = new Scanner(System.in);
String input = sc.nextLine();
String regex = "(.*)(\\d+)(.*)";
//创建一个Pattern对象
Pattern pattern = Pattern.compile(regex);
//现在创建匹配对象。
Matcher matcher = pattern.matcher(input);
if (matcher.find( )) {
System.out.println("Found value: " + matcher.group(0) );
System.out.println("Found value: " + matcher.group(1) );
System.out.println("Found value: " + matcher.group(2) );
System.out.println("Found value: " + matcher.group(3) );
} else {
System.out.println("NO MATCH");
}
}
}输出结果
Enter input text sample data with 1234 (digits) in middle Found value: sample data with 1234 (digits) in middle Found value: sample data with 123 Found value: 4 Found value: (digits) in middle
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