Java中的 Matcher useAnchoringBounds(boolean) 方法及示例

Matcher 类的useAnchoringBounds(boolean)方法用于设置此匹配器的锚定边界。通过锚定边界，这意味着如果锚定边界设置为 true，则匹配器将匹配 ^ 和 $ 等锚点以获取匹配。此方法返回一个带有修改后的锚定边界的匹配器。

句法：

public boolean useAnchoringBounds(
               boolean setAnchoringBounds)

参数：此方法采用参数setAnchoringBounds ，它是一个布尔值，描述了要修改的匹配器的锚定边界。

返回值：此方法返回一个带有修改后的锚定边界的匹配器。

下面的示例说明了 Matcher.useAnchoringBounds() 方法：

示例 1：

// Java code to illustrate useAnchoringBounds() method
  
import java.util.regex.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // Get the regex to be checked
        String regex = "(Geeks)";
  
        // Create a pattern from regex
        Pattern pattern
            = Pattern.compile(regex);
  
        // Get the String to be matched
        String stringToBeMatched
            = "GeeksForGeeks Geeks for For Geeks Geek";
  
        // Create a matcher for the input String
        Matcher matcher
            = pattern.matcher(stringToBeMatched);
  
        // set the anchoring bounds to true
        // using useAnchoringBounds() method
        matcher = matcher
                      .useAnchoringBounds(true);
  
        // Check if this matcher has anchoring bounds or not
        System.out.println("Does this matcher"
                           + " has anchoring bounds: "
                           + matcher.hasAnchoringBounds());
    }
}

输出：

Does this matcher has anchoring bounds: true

示例 2：

// Java code to illustrate useAnchoringBounds() method
  
import java.util.regex.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // Get the regex to be checked
        String regex = "(FGF)";
  
        // Create a pattern from regex
        Pattern pattern
            = Pattern.compile(regex);
  
        // Get the String to be matched
        String stringToBeMatched
            = "FGF GFG GFG FGF";
  
        // Create a matcher for the input String
        Matcher matcher
            = pattern.matcher(stringToBeMatched);
  
        // set the anchoring bounds to true
        // using useAnchoringBounds() method
        matcher = matcher
                      .useAnchoringBounds(false);
  
        // Check if this matcher has anchoring bounds or not
        System.out.println("Does this matcher"
                           + " has anchoring bounds: "
                           + matcher.hasAnchoringBounds());
    }
}

输出：

Does this matcher has anchoring bounds: false

参考： https://docs.oracle.com/javase/9/docs/api/ Java/util/regex/Matcher.html#useAnchoringBounds-boolean-