How to append to beginning of java string using replace with regex?

Question

How can I use java string replaceAll or replaceFirst to append to beginning?

String joe = "Joe";
String helloJoe = joe.replaceAll("\\^", "Hello");

Desired Output: "Hello Joe"

You can't "append to the beginning of a string" anyway since strings in Java are immutable. You'll create a new string object anyway. — fge
– fge, Commented Mar 15, 2015 at 2:15
Okey dokey! lambdaStuff.map(s->s.replace("^","Hello")).orElse("")); — genxgeek
– genxgeek, Commented Mar 15, 2015 at 5:19

Avinash Raj · Accepted Answer · 2015-03-15 02:23:24Z

5

You don't need to escape ^ because ^ is a special meta character in regex which matches the start of a line.

String helloJoe = whatever.replaceFirst("^", "Hello ");

edited Mar 15, 2015 at 2:23

answered Mar 15, 2015 at 2:14

Avinash Raj

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Elliott Frisch · Accepted Answer · 2015-03-15 02:15:00Z

2

You could perform a simple String append with +, or String.format(String, Object...) like

String whatever = "Joe";
String helloJoe = String.format("Hello %s", whatever);
// String helloJoe = "Hello " + whatever;
System.out.println(helloJoe);

Output is (as requested)

Hello Joe

answered Mar 15, 2015 at 2:15

Elliott Frisch

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