Matcher lookingAt() 方法在 Java 中的示例


java.util.regex.Matcher 類表示執行各種匹配操作的引擎。該類沒有建構函式,你可以使用 java.util.regex.Pattern 類的 matches() 方法建立/獲取該類的一個物件。

Matcher 類的 lookingAt() 方法從區域開頭開始使用模式匹配給定的輸入文字。如果匹配,此方法將返回 true,否則返回 false。與 matches() 方法不同,此方法不需要整個區域中的匹配才能返回 true。

示例 1

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Test {
   public static void main(String[] args) {
      String regex = "(.*)(\d+)(.*)";
      String input = "This is a sample Text, 1234, with numbers in between. "
         + "\n This is the second line in the text "
         + "\n This is third line in the text";
      //Creating a pattern object
      Pattern pattern = Pattern.compile(regex);
      //Creating a Matcher object
      Matcher matcher = pattern.matcher(input);
      //checking for the match
      if(matcher.lookingAt()) {
         System.out.println("Match found");
      } else {
         System.out.println("Match not found");
      }
   }
}

輸出

Match found

示例 2

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class LookingAtExample {
   public static void main(String args[]) {
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter String1: ");
      String input1 = sc.nextLine();
      System.out.println("Enter String2: ");
      String input2 = sc.nextLine();
      System.out.println("Enter String3: ");
      String input3 = sc.nextLine();
      String input = input1+"\n"+input2+"\n"+input3;
      System.out.println(input);
      //Regular expression to match a word that contain digits
      String regex = ".*\d+.*";
      //Compiling the regular expression
      Pattern pattern = Pattern.compile(regex);
      //Retrieving the matcher object
      Matcher matcher = pattern.matcher(input);
      //verifying whether match occurred
      boolean bool = matcher.lookingAt();
      if(bool) {
         System.out.println("Given input contains digit");
      } else {
         System.out.println("Given input does not contain any digit");
      }
   }
}

輸出

Enter String1:
sample text2
Enter String2:
data
Enter String3:
sample
sample text2
data
sample
Given input contains digit

更新於:20-Nov-2019

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