Question

In Java, str=str.replaceAll("\\W", " ");
what does the \\ and W means ? Thank you !

Answer 1

Hi,Let me know if you need more information:-

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StringReplace.java

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public class StringReplace {

   public static void main(String[] args) {

       String str = new String(
               "__ a ! . 1   élève BCD GOÄ_432 GOÄ_432 ; : - ఆది - A a gefräßig gefräßig gefrä GHD \\W ` ~ @ # $ % ^ & * ( ) - _ + = ] [ { } \\ | ");
       String str1 = new String(str);
       System.out.println(str);
       str = str.replaceAll("\\W", "|NONWORD|");
       // --> \W means A non word character
       System.out.println("[" + str + "]");
       System.out.println();
       // --> \w matches word characters
       str1 = str1.replaceAll("\\w", "|WORD|");
       System.out.println("[" + str1 + "]");

       // --> \ means you are skipping character next to it.
       String str3 = "\\5\\7"; // Here actual string value is --> \\5\\7
       System.out.println("\5\6");
       System.out.println("Actual:"+str3);
       // to skip the values you are mentioning \ before \5 and \7
       String replace = "\\\\";
       System.out.println(replace);
       str3 = str3.replaceAll("\\\\", "-");
       // the actual value i want to replace in the above string is --> \ so i
       // am giving \\
       // now \5\7 will become --> -5-7
       System.out.println("Value: " + str3);

       // Description:
       // \ --> escape character in java Strings.
   }

}

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OUTPUT:-

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__ a ! . 1   élève BCD GOÄ_432 GOÄ_432 ; : - ఆది - A a gefräßig gefräßig gefrä GHD \W ` ~ @ # $ % ^ & * ( ) - _ + = ] [ { } \ |
[__|NONWORD|a|NONWORD||NONWORD||NONWORD||NONWORD||NONWORD|1|NONWORD||NONWORD|l|NONWORD|ve|NONWORD|BCD|NONWORD|GO|NONWORD|_432|NONWORD|GO|NONWORD|_432|NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD|A|NONWORD|a|NONWORD|gefr|NONWORD||NONWORD|ig|NONWORD|gefr|NONWORD||NONWORD|ig|NONWORD|gefr|NONWORD||NONWORD|GHD|NONWORD||NONWORD|W|NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD|_|NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD||NONWORD|]

[|WORD||WORD| |WORD| ! . |WORD|   é|WORD|è|WORD||WORD| |WORD||WORD||WORD| |WORD||WORD|Ä|WORD||WORD||WORD||WORD| |WORD||WORD|Ä|WORD||WORD||WORD||WORD| ; : - ఆది - |WORD| |WORD| |WORD||WORD||WORD||WORD|äß|WORD||WORD| |WORD||WORD||WORD||WORD|äß|WORD||WORD| |WORD||WORD||WORD||WORD|ä |WORD||WORD||WORD| \|WORD| ` ~ @ # $ % ^ & * ( ) - |WORD| + = ] [ { } \ | ]

Actual:\5\7
\\
Value: -5-7

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Thanks