Eclipse plugin PMD suggests me to use 

```
str.charAt(0) == 'a'

```

instead of 

```
str.startWith("a")

```

But I don't want to make code more complicated and I believe that java compilers are very smart and they improve performance of str.startWith("a") by converting it into str.charAt(0) == 'a' (or something similar).

Am I right?