How to replace a substring of a string [duplicate]

Answer 1

By regex i think this is java, the method replaceAll() returns a new String with the substrings replaced, so try this:

String teste = "abcd=0; efgh=1";

String teste2 = teste.replaceAll("abcd", "ffffdd");

System.out.println(teste2);

Output:

ffffdd=0; efgh=1

Answer 2

You are probably not assigning it after doing the replacement or replacing the wrong thing. Try :

String haystack = "abcd=0; efgh=1";
String result = haystack.replaceAll("abcd","ffffdd");

Answer 3

In javascript:

var str = "abcdaaaaaabcdaabbccddabcd";
document.write(str.replace(/(abcd)/g,"----"));
//example output: ----aaaaa----aabbccdd----

In other languages, it would be something similar. Remember to enable global matches.

Answer 4

You need to use return value of replaceAll() method. replaceAll() does not replace the characters in the current string, it returns a new string with replacement.

• String objects are immutable, their values cannot be changed after they are created.
• You may use replace() instead of replaceAll() if you don't need regex.

    String str = "abcd=0; efgh=1";
    String replacedStr = str.replaceAll("abcd", "ffffdd");

    System.out.println(str);
    System.out.println(replacedStr);

outputs

abcd=0; efgh=1
ffffdd=0; efgh=1

Answer 5

You need to create the variable to assign the new value to, like this:

String str = string.replaceAll("abcd","ffffdd");

Answer 6

Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string; see Matcher.replaceAll. Use Matcher.quoteReplacement(java.lang.String) to suppress the special meaning of these characters, if desired.

from javadoc.