虽然这个问题已经有了答案,但我对字符串替换的性能很感兴趣,所以进行了一个小测试。因此,我将我的示例代码添加到这里,供所有对结果感兴趣的人使用。我已经以这种方式编写了测试,可以添加其他替换策略来测试自己的。
我有一个测试驱动程序(没有JUnit,这样更容易复制和粘贴)
public class StringReplaceTest {
public static void main(String[] args) {
int iterations = 1000000;
String[] exclude = { "one", "two", "three" };
String input = "if we add one and two we get three";
StringRemove replaceAll = new StringReplaceAll();
StringRemove replace = new StringReplace();
StringRemove stringUtilsRemove = new StringUtilsRemove();
assertStringRemove(replaceAll);
assertStringRemove(replace);
assertStringRemove(stringUtilsRemove);
profileStringRemove(replaceAll, input, exclude, iterations);
profileStringRemove(replace, input, exclude, iterations);
profileStringRemove(stringUtilsRemove, input, exclude, iterations);
}
private static void assertStringRemove(StringRemove stringRemove) {
String[] exclude = { "one", "two", "three" };
String input = "if we add one and two we get three";
String replaced = stringRemove.remove(input, exclude);
String expected = "if we add and we get ";
if (!expected.equals(replaced)) {
throw new IllegalStateException(
"String was not replaced correctly. Excpected <" + expected
+ "> but was <" + replaced + ">");
}
}
private static void profileStringRemove(StringRemove stringRemove,
String input, String[] subStringsToRemove, int iterations) {
long start = System.currentTimeMillis();
int testCount = iterations;
while (iterations-- > 0) {
stringRemove.remove(input, subStringsToRemove);
}
long end = System.currentTimeMillis();
printSummery(stringRemove.getClass().getSimpleName(), testCount, start,
end);
}
private static void printSummery(String action, int iterations, long start,
long end) {
System.out.println(action + " took: " + (end - start) + " ms for "
+ iterations + " iterations");
}
还有不同的字符串替换策略:
public interface StringRemove {
public String remove(String input, String... subStringsToRemove);
}
public class StringReplaceAll implements StringRemove {
public String remove(String input, String... subStringsToRemove) {
for (int ix = 0; ix < subStringsToRemove.length; ix++) {
input = input.replaceAll(subStringsToRemove[ix], "");
}
return input;
}
}
public class StringReplace implements StringRemove {
public String remove(String input, String... subStringsToRemove) {
for (int ix = 0; ix < subStringsToRemove.length; ix++) {
int replaceLength = 0;
while (replaceLength != input.length()) {
input = input.replace(subStringsToRemove[ix], "");
replaceLength = input.length();
}
}
return input;
}
}
public class StringUtilsRemove implements StringRemove {
public String remove(String input, String... subStringsToRemove) {
for (int ix = 0; ix < subStringsToRemove.length; ix++) {
input = StringUtils.remove(input, subStringsToRemove[ix]);
}
return input;
}
}
我的电脑上的结果是:
StringReplaceAll took: 3456 ms for 1000000 iterations
StringReplace took: 3162 ms for 1000000 iterations
StringUtilsRemove took: 761 ms for 1000000 iterations