如何更换所有星号？

Question

In Java, I want to replace all * characters with \\* .

Example: Text: select * from blah

Result: select \\\\* from blah

public static void main(String[] args) {
    String test = "select * from blah";
    test = test.replaceAll("*", "\\*");
    System.out.println(test);
}

This does not work, nor does adding a escape backslash.

Answer 1

I figured it out

    String test = "select * from blah *asdf";
    test = test.replaceAll("\\*", "\\\\*");
    System.out.println(test);

Answer 2

You don't need any regex functionality for this, so you should use the non-regex version String.replace(CharSequence, CharSequence) :

String test = "select * from blah *asdf";
test = test.replace("*", "\\*");
System.out.println(test);

Answer 3

For those of you keeping score at home, and since understanding the answer may be helpful to someone else...

String test = "select * from blah *asdf";
test = test.replaceAll("\\*", "\\\\*");
System.out.println(test);

works because you must escape the special character * in order to make the regular expression happy. However, \\ is a special character in a Java string, so when building this regex in Java, you must also escape the \\ , hence \\\\* .

This frequently leads to what amounts to double-escapes when putting together regexes in Java strings.