Most efficient way of converting String to Integer in java

Question

There are many ways of converting a String to an Integer object. Which is the most efficient among the below:

Integer.valueOf()
Integer.parseInt()
org.apache         


        

Answer 1

I tried a comparison of valueOf, parseInt, Ints.tryParse, NumberUtils.createInteger and NumberUtils.toInt with the program below. I was on jdk 1.8.0

As expected, the methods that did not need to create an Integer object were the fastest. My results were:

valueOf took: 77
parseInt took: 61
Ints.tryParse took: 117
numberUtils.createInteger took: 169
numberUtils.toInt took: 63 

So the summary is:

If you can get by using an int, use Integer.parseInt.

If you absolutely need an Integer, use Integer.valueOf

If you need the convenience of not handling exceptions when you parse, or if you are unsure of the format of the input (i.e its a string that need not be a number) use Ints.tryParse

The code I used was:

public class HelloWorld {

public static int limit = 1000000;
public static String sint = "9999";

public static void main(String[] args) {

    long start = System.currentTimeMillis();
    for (int i = 0; i < limit; i++) {
       Integer integer = Integer.valueOf(sint);
    }
    long end = System.currentTimeMillis();

    System.out.println("valueOf took: " + (end - start));


    start = System.currentTimeMillis();
    for (int i = 0; i < limit; i++) {
        int integer = Integer.parseInt(sint);
    }
    end = System.currentTimeMillis();

    System.out.println("parseInt took: " + (end - start));


    start = System.currentTimeMillis();
    for (int i = 0; i < limit; i++) {
        int integer = Ints.tryParse(sint);
    }
    end = System.currentTimeMillis();

    System.out.println("Ints.tryParse took: " + (end - start));


    start = System.currentTimeMillis();
    for (int i = 0; i < limit; i++) {
        Integer integer = NumberUtils.createInteger(sint);
    }
    end = System.currentTimeMillis();

    System.out.println("numberUtils.createInteger took: " + (end - start));

    start = System.currentTimeMillis();
    for (int i = 0; i < limit; i++) {
        int integer = NumberUtils.toInt(sint);
    }
    end = System.currentTimeMillis();

    System.out.println("numberUtils.toInt took: " + (end - start));

}
}