Java中的 Matcher appendReplacement(StringBuilder, String) 方法及示例

Matcher 类的appendReplacement(StringBuilder, String)方法表现为追加和替换方法。此方法读取输入字符串并将其替换为匹配器字符串中的匹配模式。

句法：

public Matcher 
    appendReplacement(StringBuilder builder, 
                      String stringToBeReplaced)

参数：此方法有两个参数：

• builder ：这是存储目标字符串的 StringBuilder 。
• stringToBeReplaced ：这是匹配器中要替换的字符串。

返回值：此方法返回一个替换了目标字符串的匹配器。

异常：此方法抛出以下异常：

• IllegalStateException ：如果尚未尝试匹配，或者之前的匹配操作失败
• IllegalArgumentException ：如果替换字符串引用了模式中不存在的命名捕获组
• IndexOutOfBoundsException ：如果替换字符串引用了模式中不存在的捕获组

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

示例 1：

// Java code to illustrate appendReplacement() 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);
  
        System.out.println("Before Replacement: "
                           + stringToBeMatched);
  
        // Get the String to be replaced
        String stringToBeReplaced = "GEEKS";
        StringBuilder builder = new StringBuilder();
  
        // Replace every matched pattern
        // with the target String
        // using appendReplacement() method
        while (matcher.find()) {
            matcher.appendReplacement(builder,
                                      stringToBeReplaced);
        }
        matcher.appendTail(builder);
  
        // Print the replaced matcher
        System.out.println("After Replacement: "
                           + builder.toString());
    }
}

输出：

Before Replacement: GeeksForGeeks Geeks for For Geeks Geek
After Replacement: GEEKSForGEEKS GEEKS for For GEEKS Geek

示例 2：

// Java code to illustrate appendReplacement() 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 FGF FGF FGF";
  
        // Create a matcher for the input String
        Matcher matcher
            = pattern.matcher(stringToBeMatched);
  
        System.out.println("Before Replacement: "
                           + stringToBeMatched);
  
        // Get the String to be replaced
        String stringToBeReplaced = "GFG";
        StringBuilder builder = new StringBuilder();
  
        // Replace every matched pattern
        // with the target String
        // using appendReplacement() method
        while (matcher.find()) {
            matcher.appendReplacement(builder,
                                      stringToBeReplaced);
        }
        matcher.appendTail(builder);
  
        // Print the replaced matcher
        System.out.println("After Replacement: "
                           + builder.toString());
    }
}

输出：

Before Replacement: FGF FGF FGF FGF
After Replacement: GFG GFG GFG GFG

参考： https://docs.oracle.com/javase/9/docs/api/ Java/util/regex/Matcher.html#appendReplacement-java.lang.StringBuilder-java.lang.String-