匹配器替换 Java 中的 First(字符串)方法，示例
原文:https://www . geesforgeks . org/matcher-replaceferstring-method-in-Java-with-examples/
Matcher 类的 replaceFirst() 方法表现为一种追加和替换方法。此方法读取输入字符串，并用匹配器字符串中的第一个匹配模式替换它。
语法:
public String replaceFirst(String stringToBeReplaced)
参数:要替换的字符串，即匹配器中要替换的字符串。
返回类型:通过替换字符串构造目标字符串的字符串。
例 1:
Java 语言(一种计算机语言，尤用于创建网站)
// Java Program to Illustrate replaceFirst() Method
// of Matcher class
// Importing required classes
import java.util.regex.*;
// Main class
public class GFG {
// Main driver method
public static void main(String[] args)
{
// Getting the regex to be checked
String regex = "(Geeks)";
// Creating a pattern from regex
Pattern pattern = Pattern.compile(regex);
// Getting the String to be matched
String stringToBeMatched
= "GeeksForGeeks Geeks for For Geeks Geek";
// Creating a matcher for the input String
Matcher matcher
= pattern.matcher(stringToBeMatched);
// Displaying the string to be matched
// before replacing
System.out.println("Before Replacement: "
+ stringToBeMatched);
// Getting the string to be replaced
String stringToBeReplaced = "GFG";
StringBuilder builder = new StringBuilder();
// Replacing every matched pattern with the target
// string using replaceFirst() method
System.out.println(
"After Replacement: "
+ matcher.replaceFirst(stringToBeReplaced));
}
}
Output:
Before Replacement: GeeksForGeeks Geeks for For Geeks Geek
After Replacement: GFGForGeeks Geeks for For Geeks Geek
例 2:
Java 语言(一种计算机语言，尤用于创建网站)
// Java Program to Illustrate replaceFirst() Method
// Importing required classes
import java.util.regex.*;
// Main class
public class GFG {
// Main driver method
public static void main(String[] args)
{
// Getting the regex to be checked
String regex = "(FGF)";
// Creating a pattern from regex
Pattern pattern = Pattern.compile(regex);
// Getting the string to be matched
String stringToBeMatched = "FGF FGF FGF FGF";
// Creating a matcher for the input String
Matcher matcher
= pattern.matcher(stringToBeMatched);
// Printing string on console
// before replacement
System.out.println("Before Replacement: "
+ stringToBeMatched);
// Getting the string to be replaced
String stringToBeReplaced = "GFG";
StringBuilder builder = new StringBuilder();
// Replacing every matched pattern with target
// string using replaceFirst() method and printing
// the string to be replaced
System.out.println(
"After Replacement: "
+ matcher.replaceFirst(stringToBeReplaced));
}
}
Output:
Before Replacement: FGF FGF FGF FGF
After Replacement: GFG FGF FGF FGF
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