我在ARM v6处理器上运行
Java软件.这个程序的性质要求我将一些数字(int或float)转换为String.处理器运行速度为850Mhz. Java Runtime是OpenJDK Zero VM 1.7.0_21-b02.
我并不期待这里有坚如磐石的表演,但我希望能比我在下面的代码片段中看到的更有效.
long time1, time2;
float[] src = new float[2000000];
for (int i = 0; i < src.length; i++) {
src[i] = (float)Math.random()* 2.56454512f * (float) Math.random();
}
time1 = System.nanoTime();
for (int j = 0; j < src.length; j++) {
String test = String.valueOf(src[j]);
}
time2 = System.nanoTime();
logTimeDelay("String.valueOf", time1, time2);
time1 = System.nanoTime();
for (int j = 0; j < src.length; j++) {
String test = Float.toString(src[j]);
}
time2 = System.nanoTime();
logTimeDelay("Float.toString", time1, time2);
StringBuilder sb = new StringBuilder(50);
time1 = System.nanoTime();
for (int j = 0; j < src.length; j++) {
sb.setLength(0);
sb.append(src[j]);
}
time2 = System.nanoTime();
logTimeDelay("StringBuilder.append, setLength", time1, time2);
time1 = System.nanoTime();
for (int j = 0; j < src.length; j++) {
String test = "" + src[j];
}
time2 = System.nanoTime();
logTimeDelay("\"\" + ", time1, time2);
private static void logTimeDelay(String message, long time1, long time2){
System.out.println(String.format(message + ": %.5f s", (float) (time2 - time1) / 1.0e9));
}
在我的i7计算机上运行此代码段会返回以下结果：
String.valueOf: 0.39714 s
Float.toString: 0.33295 s
StringBuilder.append, setLength: 0.33277 s
"" + : 0.37581 s
在ARMv6处理器上运行完全相同的代码段会返回以下值：
String.valueOf: 204.78758 s
Float.toString: 200.79659 s
StringBuilder.append, setLength: 180.81551 s
"" + : 267.63036 s
有关如何在此设备上优化我的数字到int转换的任何线索？
提前致谢.
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