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How to replace a string exactly as it is?

Consider the following code:
String str = "folder1;b";
String replacement = "C:\\myfolder";
System.out.println(str.replaceAll("b", replacement));
This printsC:myfolder.
How can I replace str with the replacement string as is? (Without the slashes being removed)
I've tried Pattern.quote(replacement) but that prints \QC:\Development\E
I have no control over replacement which comes from an external source and it is not known what its contents would be.

If you aren't using regular expressions, better to use String.replace():
String str = "folder1;b";
String replacement = "C:\\myfolder";
System.out.println(str.replace("b", replacement));
String.replace() does a literal replacement, it doesn't treat the arguments as regular expressions.
I will point out that you will run into trouble if your str is folder1;bash;b as both of the bs will be replaced.

String.replaceAll uses regex. You don't need that.
Try this:
String str = "b";
String replacement = "C:\\myfolder";
System.out.println(str.replace(str,replacement);

The second parameter of String.replaceAll expect a regex. In the regex world a \ has a special operator meaning. You have to escape it once for the jvm and once for regex.
String str = "b";
String replacement = "C:\\\\\\\\myfolder";
System.out.println(str.replaceAll(str, replacement));
Will print out
C:\\myfolder
With String.replace it does take the literal string and thus you only have to escape it once for the jvm
String str = "b";
String replacement = "C:\\\\myfolder";
System.out.println(str.replace(str, replacement));
Will print
C:\\myfolder
And lastly, if you have no idea how the incoming replacement String looks like you can escape it beforehand with
String str = "b";
String replacement = "C:\\myfolder"; // might be anything
String actualReplacement = replacement.replaceAll("\\\\", "\\\\\\\\");
System.out.println(str.replace(str, actualReplacement));
Will print
C:\\myfolder
Other than that you could use one of the apache.utils to achieve it, but this one here is without any third party library.

Regex to convert this String

How can I convert this String AB23-01-0001 to AB23010001( replacing the "-" with "") and AB230001 (removing the middle part) using regex in Java, right row I'm using replace for the first case and substring and appending them into a SB for the second case. Just wanted to know how to achieve it using REGEX.

Why not use the method built into the String class?
String newString = "AB23-01-0001".replaceAll("[-]", "");
Note the use of [] - a regex string, since you are just replacing a -, you can omit them.

str = "AB23-01-0001"
happy = str.replaceAll("[^a-zA-Z0-9]", "");
from https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#replaceAll(java.lang.String,%20java.lang.String)

Try this:
Pattern p1 = Pattern.compile("-[^-]*-");
Matcher m1 = p1.matcher("AB23-01-0001");
System.out.println(m1.replaceAll(""));
To test it
A replacement to the patter is Pattern.compile("-[\\d\\w]+-")

You can use build-in method to remove both parts at once with RegEx:
String value = "AB23-01-0001";
value = value.replaceAll("-[\\d\\w]+-", "");

Replace String ignoring case in Java [duplicate]

This question already has answers here:
How to replace case-insensitive literal substrings in Java
(10 answers)
Closed 7 years ago.
String Checkout = D:\ifs\APP\Checkout
String DeleteLine = D:\IFS\APP\Checkout\trvexp\client\Ifs.App\text.txt
Note the ifs and IFS in both Strings.
I want to replace the Checkout String in the Deleted Line
So the final String would look like this:
\trvexp\client\Ifs.App\text.txt
Following is what I have tried, but obviously due to Case Sensitivity, the string won't get replaced. Any Solution or a work around for this?
String final = DeleteLine.replace(Checkout, "");

String.replace() doesn't support regex. You need String.replaceAll().
DeleteLine.replaceAll("(?i)" + Pattern.quote(Checkout), "");

Put (?i) in the replaceAll method's regular expression:
String finalString = DeleteLine.replaceAll("(?i)" + Checkout, "");

You can do this:
String Checkout = "D:\\\\ifs\\\\APP\\\\Checkout";
String DeleteLine = "D:\\IFS\\APP\\Checkout\\trvexp\\client\\Ifs.App\\text.txt";
String f = DeleteLine.replaceFirst("(?i)"+Checkout, "");

Alternatively, if youi want the pattern on a specific portion you can do it manually. You can declare the checkout Sting as:
String Checkout= \Q(?i)D:\ifs\APP\Checkout\E
as
\Q means "start of literal text"
\E means"end of literal text"
and then do the replace
String final = DeleteLine.replace(Checkout, "");

Replace String variable with exact string

If i want to replace one string variable with exact string in java, what can I do?
I know that replace in java , replace one exact string with another, but now i have string variable and i want to replace it's content with another exact string.
for example:
`String str="abcd";
String rep="cd";`
Now I want to replace rep content with"kj"
It means that I want to have str="abkj" at last.

If I understand your question, you could use String.replace(CharSequence, CharSequence) like
String str="abcd";
String rep="cd";
String nv = "kj";
str = str.replace(rep, nv); // <-- old, new
System.out.println(str);
Output is (the requested)
abkj

i think he wants:
String toReplace = "REPLACE_ME";
"REPLACE_ME What a nice day!".replace(toReplace,"");
"REPLACEME What a nice day!".replace(toReplace,"") results in:
" What a nice day!"

How to replace all numbers in java string

I have string like this String s="ram123",d="ram varma656887"
I want string like ram and ram varma so how to seperate string from combined string
I am trying using regex but it is not working
PersonName.setText(cursor.getString(cursor.getColumnIndex(cursor
.getColumnName(1))).replaceAll("[^0-9]+"));

The correct RegEx for selecting all numbers would be just [0-9], you can skip the +, since you use replaceAll.
However, your usage of replaceAll is wrong, it's defined as follows: replaceAll(String regex, String replacement). The correct code in your example would be: replaceAll("[0-9]", "").

You can use the following regex: \d for representing numbers. In the regex that you use, you have a ^ which will check for any characters other than the charset 0-9
String s="ram123";
System.out.println(s);
/* You don't need the + because you are using the replaceAll method */
s = s.replaceAll("\\d", ""); // or you can also use [0-9]
System.out.println(s);

To remove the numbers, following code will do the trick.
stringname.replaceAll("[0-9]","");

Please do as follows
String name = "ram varma656887";
name = name.replaceAll("[0-9]","");
System.out.println(name);//ram varma
alternatively you can do as
String name = "ram varma656887";
name = name.replaceAll("\\d","");
System.out.println(name);//ram varma
also something like given will work for you
String given = "ram varma656887";
String[] arr = given.split("\\d");
String data = new String();
for(String x : arr){
data = data+x;
}
System.out.println(data);//ram varma

i think you missed the second argument of replace all. You need to put a empty string as argument 2 instead of actually leaving it empty.
try
replaceAll(<your regexp>,"")

you can use Java - String replaceAll() Method.
This method replaces each substring of this string that matches the given regular expression with the given replacement.
Here is the syntax of this method:
public String replaceAll(String regex, String replacement)
Here is the detail of parameters:
regex -- the regular expression to which this string is to be matched.
replacement -- the string which would replace found expression.
Return Value:
This method returns the resulting String.
for your question use this
String s = "ram123", d = "ram varma656887";
System.out.println("s" + s.replaceAll("[0-9]", ""));
System.out.println("d" + d.replaceAll("[0-9]", ""));