Date: 2017sep28
Update: 2025sep29
Language: Java
Q. Java: Best way to insert a String into another String
A. Use StringBuilder.insert() as shown in this full example:
class Demo {
// Insert before * in a string.
static String insertBeforeStar(final String in, final String more) {
StringBuilder sb = new StringBuilder(in);
int i = in.indexOf('*');
if (i < 0) return in;
sb.insert(i, more);
return sb.toString();
}
public static final void main(String []args) {
String out = insertBeforeStar("one * three", "two");
System.out.println("out=" + out);
}
}
Output:
out=one two* three
Of course, this isn't best in every case.
But it's less error prone than using multiple substring()s.