Java String replaceAll() usage and example

Java String(문자열) 메서드

The Java String replaceAll() method replaces each substring that matches the regular expression in the string with the specified text.

The syntax of the replaceAll() method is:

string.replaceAll(String regex, String replacement)

replaceAll() parameters

The replaceAll() method has two parameters.

• regex - The regular expression to be replaced (can be a typical string)

• replacement - The matched substring is replaced by this string

replaceAll() return value

• The replaceAll() method returns a new string in which each occurrence of the matched substring is replaced by the replacement string (replacement).

example1: Java String replaceAll() method

class Main {
　　　　public static void main(String[] args) {
　　　　　　　　String str1　= "aabbaaac";
　　　　　　　　String str2　= "Learn223Java55@";
　　　　　　　　//Regular expression representing a sequence of numbers
　　　　　　　　String regex = "\\d+";
　　　　　　　　//All occurrences of "aa" are replaced with "zz"
　　　　　　　　System.out.println(str1.replaceAll("aa", "zz"));　//　zzbbzzac
　　　　　　　　//Replace numbers or number sequences with spaces
　　　　　　　　System.out.println(str2.replaceAll(regex, " "));　//　Learn Java @
　　　　}
}

In the above example, "\\d+" is a regular expression that matches one or more numbers.

Escaping characters in replaceAll()

The replaceAll() method can take a regular expression or a typical string as the first parameter. This is because a typical string itself is a regular expression.

In regular expressions, some characters have special meanings. These meta-characters are:

\　^　$　.　|　?　*　+　{}　[]　()

If you need to match substrings containing these meta-characters, you can use \ or use the replace() method to escape these characters.

//　Program to replace the　+　character
class Main {
　　　　public static void main(String[] args) {
　　　　　　　　String str1　= "+a-+b";
　　　　　　　　String str2　= "Learn223Java55@";
　　　　　　　　String regex = "\\+";
　　　　　　　　//　대체+"　를 "#"로 대체"를 사용하여 replaceAll() 메서드
　　　　　　　　////replaceAll()를 사용하여 “　+”대체”를 “#”로
　　　　　　　　System.out.println(str1.replaceAll("\\+"", "#"));　//　#a-#b
　　　　　　　　//　대체+"　를　"#"　로　replace()를 사용하여 대체"　
　　　　　　　　System.out.println(str1.replace("+"", "#"));　//　#a-#b
　　　　}
}

처음에 보았던 것처럼, replace() 메서드를 사용할 때는 특수 문자를 인코딩할 필요가 없습니다. 더 많은 정보를 얻으려면 다음을 방문하세요:Java String replace()

만약 첫 번째 일치하는 부분 문자열만을 대체하려면, 다음을 사용하세요:Java String replaceFirst()메서드。

Java String(문자열) 메서드