Я использую следующий код, чтобы проверить, насколько медленным является блок try. К моему удивлению, блок try делает это быстрее. Почему?
public class Test {
int value;
public int getValue() {
return value;
}
public void reset() {
value = 0;
}
// Calculates without exception
public void method1(int i) {
value = ((value + i) / i) << 1;
// Will never be true
if ((i & 0xFFFFFFF) == 1000000000) {
System.out.println("You'll never see this!");
}
}
public static void main(String[] args) {
int i;
long l;
Test t = new Test();
l = System.currentTimeMillis();
t.reset();
for (i = 1; i < 100000000; i++) {
t.method1(i);
}
l = System.currentTimeMillis() - l;
System.out.println("method1 took " + l + " ms, result was "
+ t.getValue());
// using a try block
l = System.currentTimeMillis();
t.reset();
for (i = 1; i < 100000000; i++) {
try {
t.method1(i);
} catch (Exception e) {
}
}
l = System.currentTimeMillis() - l;
System.out.println("method1 with try block took " + l + " ms, result was "
+ t.getValue());
}
}
В моей машине работают 64-разрядные Windows 7 и 64-разрядные JDK7. Я получил следующий результат:
method1 took 914 ms, result was 2
method1 with try block took 789 ms, result was 2
И я запускаю код много раз, и каждый раз, когда у меня получается почти тот же результат.
Update:
Вот результат десятикратного запуска теста на MacBook Pro, Java 6. Try-catch делает метод быстрее, так же как и в Windows.
method1 took 895 ms, result was 2
method1 with try block took 783 ms, result was 2
--------------------------------------------------
method1 took 943 ms, result was 2
method1 with try block took 803 ms, result was 2
--------------------------------------------------
method1 took 867 ms, result was 2
method1 with try block took 745 ms, result was 2
--------------------------------------------------
method1 took 856 ms, result was 2
method1 with try block took 744 ms, result was 2
--------------------------------------------------
method1 took 862 ms, result was 2
method1 with try block took 744 ms, result was 2
--------------------------------------------------
method1 took 859 ms, result was 2
method1 with try block took 765 ms, result was 2
--------------------------------------------------
method1 took 937 ms, result was 2
method1 with try block took 767 ms, result was 2
--------------------------------------------------
method1 took 861 ms, result was 2
method1 with try block took 744 ms, result was 2
--------------------------------------------------
method1 took 858 ms, result was 2
method1 with try block took 744 ms, result was 2
--------------------------------------------------
method1 took 858 ms, result was 2
method1 with try block took 749 ms, result was 2