Java String StringBuffer StringBuilder 效率测试

　　

 

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

package ersatz;   import java.io.FileNotFoundException;   public class Ersatz {   public static void main(String[] args) throws FileNotFoundException {     long commenceTime = 0L;     long closureTime = 0L;     StringBuffer buffer = new StringBuffer("");       commenceTime = System.currentTimeMillis();     for (int i = 0; i < 80000; ++i) {       buffer.append(String.valueOf(i));     }     closureTime = System.currentTimeMillis();     System.out.println("StringBuffer elapsed: " + (closureTime - commenceTime));       StringBuilder builder = new StringBuilder("");     commenceTime = System.currentTimeMillis();     for (int i = 0; i < 80000; ++i) {       builder.append(String.valueOf(i));     }     closureTime = System.currentTimeMillis();     System.out.println("StringBuilder elapsed: " + (closureTime - commenceTime));     String str = "";     commenceTime = System.currentTimeMillis();     for (int i = 0; i < 80000; ++i) {       str += String.valueOf(i);     }     closureTime = System.currentTimeMillis();     System.out.println("String elapsed: " + (closureTime - commenceTime));   } }