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

Your best bet is to use Integer.parseInt. This will return an int, but this can be auto-boxed to an Integer. This is slightly faster than valueOf, as when your numbers are between -128 and 127 it will use the Integer cache and not create new objects. The slowest is the Apache method.

private String data = "99";

public void testParseInt() throws Exception {
    long start = System.currentTimeMillis();
    long count = 0;
    for (int i = 0; i < 100000000; i++) {
        Integer o = Integer.parseInt(data);
        count += o.hashCode();
    }
    long diff = System.currentTimeMillis() - start;
    System.out.println("parseInt completed in " + diff + "ms");
    assert 9900000000L == count;
}

public void testValueOf() throws Exception {
    long start = System.currentTimeMillis();
    long count = 0;
    for (int i = 0; i < 100000000; i++) {
        Integer o = Integer.valueOf(data);
        count += o.hashCode();
    }
    long diff = System.currentTimeMillis() - start;
    System.out.println("valueOf completed in " + diff + "ms");
    assert 9900000000L == count;
}


public void testIntegerConverter() throws Exception {
    long start = System.currentTimeMillis();
    IntegerConverter c = new IntegerConverter();
    long count = 0;
    for (int i = 0; i < 100000000; i++) {
        Integer o = (Integer) c.convert(Integer.class, data);
        count += o.hashCode();
    }
    long diff = System.currentTimeMillis() - start;
    System.out.println("IntegerConverter completed in " + diff + "ms");
    assert 9900000000L == count;
}

parseInt completed in 5906ms
valueOf completed in 7047ms
IntegerConverter completed in 7906ms