由3a（"aaa"）字符串得到1000字符串

//由3a（"aaa"）字符串得到1000字符串//纯字符串实现long start = System.currentTimeMillis();String str = "aaa";while(true){str += str;if(str.length() > 1000){break;}}int overFlowLength = str.length() - 1000;if(overFlowLength > 0){str = str.substring(0,1000);}long end = System.currentTimeMillis();System.out.println("time"+(end - start));System.out.println(str);System.out.println(str.length());System.out.println("=======================");//StringBilder实现start = System.currentTimeMillis();StringBuilder sb = new StringBuilder();for(int i=0;i<333;i++){sb.append("aaa");}sb.append("aaa".charAt(0));end = System.currentTimeMillis();System.out.println("time"+(end - start));System.out.println(sb);System.out.println(sb.length());