我有一个这样的循环:
for (int i = 0; i < max; i++) {
String myString = ...;
float myNum = Float.parseFloat(myString);
myFloats[i] = myNum;
}
这是一个方法的主要内容，该方法的唯一目的是返回浮点数数组。我想让这个方法在出现错误时返回null，所以我把循环放在try…Catch block，像这样:
try {
for (int i = 0; i < max; i++) {
String myString = ...;
float myNum = Float.parseFloat(myString);
myFloats[i] = myNum;
}
} catch (NumberFormatException ex) {
return null;
}
但后来我也想到试一试……Catch块在循环中，像这样:
for (int i = 0; i < max; i++) {
String myString = ...;
try {
float myNum = Float.parseFloat(myString);
} catch (NumberFormatException ex) {
return null;
}
myFloats[i] = myNum;
}
是否有任何理由，性能或其他方面，更喜欢其中一个?
编辑:共识似乎是，将循环放在try/catch中更干净，可能是在它自己的方法中。然而，关于哪个速度更快仍存在争议。有人能测试一下并给出一个统一的答案吗?
As already mentioned, the performance is the same. However, user experience isn't necessarily identical. In the first case, you'll fail fast (i.e. after the first error), however if you put the try/catch block inside the loop, you can capture all the errors that would be created for a given call to the method. When parsing an array of values from strings where you expect some formatting errors, there are definitely cases where you'd like to be able to present all the errors to the user so that they don't need to try and fix them one by one.
我把0.02美元放进去。有时，您需要在稍后的代码中添加“finally”(因为谁会在第一次就写出完美的代码呢?)在这些情况下，将try/catch放在循环之外突然变得更有意义了。例如:
try {
for(int i = 0; i < max; i++) {
String myString = ...;
float myNum = Float.parseFloat(myString);
dbConnection.update("MY_FLOATS","INDEX",i,"VALUE",myNum);
}
} catch (NumberFormatException ex) {
return null;
} finally {
dbConnection.release(); // Always release DB connection, even if transaction fails.
}
因为如果出现错误，您只希望释放一次数据库连接(或选择您最喜欢的其他资源类型……)。
