Java.toCharArray()和charAt()的效率对比分析

 public static void test() {
 String s = "a";
 for(int i = 0; i < 100000; i++) {
  s += "a";
 }
 
 long start1 = System.currentTimeMillis();
 char[] cs = s.toCharArray();
 for(char c:cs) {
  System.out.println(1); // 需要输入语句进入循环
 }
 long end1 = System.currentTimeMillis();
 
 long start2 = System.currentTimeMillis();
 for(int i = 0; i < s.length(); i++) {
  char c = s.charAt(i);
  System.out.println(1);
 }
 long end2 = System.currentTimeMillis();
 
 System.out.println(end1 - start1);
 System.out.println(end2 - start2);
 }

 
public class Demo {
	
	public static void main(String[] args){
		
		String str = "helloworld";
    char[] data = str.toCharArray();// 将字符串转为数组
    for (int x = 0; x < data.length; x++) {
      System.out.print(data[x] + " ");
      data[x] -= 32;
      System.out.print(data[x] + " ");
    }
    System.out.println(new String(data));
	}
}