StringBuilder is so much faster than string concatenation
I was googling around whether I should use StringBuilder or just regular string concatenation (s += "lol") in Java. So I found out that StringBuilder is supposed to be faster and decided to try it out. Here is the suberp code I ran to figure this out:
// STRINGBULDER
long builderStart = System.currentTimeMillis();
StringBuilder builder = new StringBuilder();
for (int i = 0; i < 999999; i++) {
builder.append(i).append("asdf").append("\n");
}
long builderEnd = System.currentTimeMillis();
// STRING CONCATENATION
long concatenationStart = System.currentTimeMillis();
String str = "";
for (int i = 0; i < 999999; i++) {
str += i + "asdf" + "\n";
}
long concatenationEnd = System.currentTimeMillis();
// RESULTS
System.out.println("StringBuilder time: " + (builderEnd - builderStart) + " ms");
System.out.println("String concatenation time: " + (concatenationEnd - concatenationStart) + " ms");
It goes through a for loop almost a million times, each time appending the string slightly. The StringBuilder was faster indeed but I 🤯 just how much faster it was:
StringBuilder time: 57 ms
String concatenation time: 673930 ms
And just to clarify, converting StringBuilder into actual String takes almost no time at all. Here are the results of the same loop + converting it to an actual string:
StringBuilder time: 60 ms
StringBuilder to String time: 16 ms
TLDR: Use StringBuilder if you're handling super long strings or something 🪂