Java中遍历字符串toCharArray()和charAt()效率比较

public static void test() {
    String s = "a";
    for(int i = 0; i < 100000; i++) {
        s += "a";
    }
    /****************toCharArray遍历*************/
    long start1 = System.currentTimeMillis();
    char[] arr = s.toCharArray();
    for (int i = 0; i < arr.length; i++) {
         char c = arr[i];
         System.out.println(c);
    }
    long end1 = System.currentTimeMillis();
    /****************charAt遍历******************/
    long start2 = System.currentTimeMillis();
    for(int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);
        System.out.println(c);
    }
    long end2 = System.currentTimeMillis();  

    System.out.println(end1 - start1);  //503
    System.out.println(end2 - start2);  //453
}  

由此得出charAt效率较高。