The replaceFirst(Function) method of Matcher Class behaves as a append-and-replace method. This method replaces first instance of the pattern matched in the matcher with the function passed in the parameter.
public String replaceFirst( Function replacerFunction)
Parameters: This method takes a parameter replacerFunction which is the function that defines the replacement of the matcher.
Return Value: This method returns a String with the target String constructed by replacing the String.
Exceptions: This method throws following exceptions:
- NullPointerException: if the replacer function is null
- ConcurrentModificationException: if it is detected that the replacer function modified this matcher’s state
Below examples illustrate the Matcher.replaceFirst() method:
Before Replacement: GeeksForGeeks Geeks for For Geeks Geek After Replacement: GEEKSForGeeks Geeks for For Geeks Geek
Before Replacement: GFG FGF GFG GFG FGF After Replacement: GFG fgf GFG GFG FGF
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