replaceAll Dangling metacharacter

Question

I have a string, say 1++++----2 and I want to replace ++++---- with a certain string, say string. The I use the java function replaceAll, but it keep warning Dangling metacharacter every time I use it:

mystring.replaceAll("++++----", "string");

If you are using fixed string replacement, use `replace` method — nhahtdh, Jul 21 '15 at 07:17
Looking at the previous question, it seems that you are approaching the problem the wrong way. — nhahtdh, Jul 21 '15 at 07:18
yes, it works. I think that replace only work with char, not string — The Dark Knight, Jul 21 '15 at 07:19

dly · Answer 1 · 2015-07-21T07:25:13.053

3

Escape the +, only the first or all doesn't matter here.

String str = "1+++---2";
str = str.replaceAll("\\+\\+\\+---", "");
System.out.println(str);

Output:

Or use replaceAllas it's meant to be used:

str = str.replaceAll("[+-]", "");

edited Jul 21 '15 at 07:25

answered Jul 21 '15 at 07:19

dly

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Suresh Atta · Answer 2 · 2015-07-21T07:27:51.223

2

replaceAll's first argument takes a regualr expression and + have special meaning in regualr expression. Escape + to make it work properly .

mystring.replaceAll("\\+\\+\\+\\+----", "string");

edited Jul 21 '15 at 07:27

answered Jul 21 '15 at 07:16

Suresh Atta

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score 1 · Answer 3 · answered Jul 21 '15 at 07:18

You can use following regex :

mystring.replaceAll("\\++-+", "string")

Since + is a regex character you need to escape it.so here in "\\++-+" the first part \\+ will match the character + literally and the second + will match 1 or more combination of character + and the rest is -+ which will match 1 or more -.

score 0 · Answer 4 · answered Jul 21 '15 at 07:24

When you replace a fixed string, you need a replace function:

String mystring  = "1++++----2";
System.out.println(mystring.replace("++++----", "string"));

See demo

Otherwise, you need a regex with replaceAll.

System.out.println(mystring.replaceAll("[+]+-+", "string"));

Note that you do not need to escape the + inside a regex character class, which is convenient in Java.

replaceAll Dangling metacharacter

4 Answers4