Using a JTextField to get a regular expression from a user. How do I make it see \t as a tab instead of a \ followed by a t

Question

JTextField reSource; //contains the regex expression the user wants to search for
String re=reSource.getText();
Pattern p=Pattern.compile(re,myflags); //myflags defined elsewhere in code
Matcher m=p.matcher(src); //src is the text to search and comes from a JTextArea
while (m.find()==true) {

• If the user enters \t it finds \t not tab.
  
• If the user enters \\\t it finds \\\t not tab.
  
• If the user enters [\t] or [\\\t] it finds t not tab.

I want it such that if the user enters \t it finds tab. Of course it also needs to work with \n, \r etc...

If re="\t"; is used instead of re=reSource.getText(); with \t in the JTextField then it finds tabs. How do I get it to work with the contents of the JTextField?

Answer 1

Example:

String src = "This\tis\ta\ttest";
System.out.println("src=\"" + src + '"'); // --> prints "This is a test"
String re="\\t";
System.out.println("re=\"" + re + '"'); // --> prints "\t" - as when you use reSource.getText();

Pattern p = Pattern.compile(re);
Matcher m = p.matcher(src);
while (m.find()) {
    System.out.println('"' + m.group() + '"');
}

Output:

src="This   is  a   test"
re="\t"
"   "
"   "
"   "

Try this:

re=re.replace("\\t", "\t");
OR
re=re.replace("\\t", "\\\\t");

I think the problem is in understanding that when you type:

String str = "\t";

Then it is actualy same as:

String str = "   ";

But if you type:

String str = "\\t";

Then the System.out.print(str) will be "\t".