Date: 2019apr12
Update: 2025sep30
Language: Java
Keywords: replace, replaceAll, regex
Level: novice
Q. Java: Change leading spaces in a String to tabs
A. Here is a simple function that does that in a full example:
class Demo {
static String leadingSpacesToTabs(final String in) {
StringBuilder sb = new StringBuilder(in);
for (int i = 0; i < sb.length(); i++) {
if (sb.charAt(i) != ' ') break;
sb.setCharAt(i, '\t');
}
return sb.toString();
}
public static final void main(String []args) {
final String spaceLine = " <div>";
System.out.println("before=" + spaceLine);
final String tabLine = leadingSpacesToTabs(spaceLine);
System.out.println(" after=" + tabLine);
}
}
Output:
before= <div>
after= <div>