Replace alphabet in a string using replace?

Question

I\'m wondering if I can use string.replace() to replace all alphabets in a string?

String sentence = \"hello world! 722\"
String str = sentence         


        

Answer 1

You can use the following (regular expression):

    String test = "hello world! 722";
    System.out.println(test);
    String testNew = test.replaceAll("(\\p{Alpha})", "@");
    System.out.println(testNew);

You can read all about it in here: http://docs.oracle.com/javase/tutorial/essential/regex/index.html

Answer 2

You replace using regular expressions with String#replaceAll. The pattern [a-zA-Z] will match all lowercase English letters (a-z) and all uppercase ones (A-Z). See the below code in action here.

final String result = str.replaceAll("[a-zA-Z]","@"); 

If you want to replace all alphabetical characters from all locales, use the pattern \p{L}. The documentation for Pattern states that:

Both \p{L} and \p{IsL} denote the category of Unicode letters.

See the below code in action here.

final String result = str.replaceAll("\\p{L}", "@");

Answer 3

Java's String#replaceAll takes a regex string as argument. Tha being said, [a-ZA-Z] matches any char from a to z (lowercase) and A to Z (uppercase) and that seems to be what you need.

String sentence = "hello world! 722";
String str = sentence.replaceAll("[a-zA-Z]", "@");
System.out.println(str); // "@@@@@ @@@@@! 722"

See demo here.

Answer 4

Use String#replaceAll that takes a Regex:

str = str.replaceAll("[a-zA-Z]", "@");

Note that String#replace takes a String as argument and not a Regex. If you still want to use it, you should loop on the String char-by-char and check whether this char is in the range [a-z] or [A-Z] and replace it with @. But if it's not a homework and you can use replaceAll, use it :)