性能:就像Jeffrey在他的回复中所说的，在Java中这并没有太大的区别。

通常，为了代码的可读性，在哪里捕获异常的选择取决于您是否希望循环继续处理。

在您的示例中，您在捕获异常时返回。在这种情况下，我会在循环中放入try/catch。如果你只是想捕捉一个坏值，但继续处理，把它放在里面。

第三种方法:您总是可以编写自己的静态ParseFloat方法，并在该方法中而不是在循环中处理异常处理。使异常处理与循环本身隔离!

class Parsing
{
    public static Float MyParseFloat(string inputValue)
    {
        try
        {
            return Float.parseFloat(inputValue);
        }
        catch ( NumberFormatException e )
        {
            return null;
        }
    }

    // ....  your code
    for(int i = 0; i < max; i++) 
    {
        String myString = ...;
        Float myNum = Parsing.MyParseFloat(myString);
        if ( myNum == null ) return;
        myFloats[i] = (float) myNum;
    }
}

如果将try/catch放在循环中，则会在异常发生后继续循环。如果你把它放在循环之外，你会在抛出异常时立即停止。

我想添加我自己的0.02c，关于在哪里放置异常处理的一般问题时两个相互竞争的考虑因素:

The "wider" the responsibility of the try-catch block (i.e. outside the loop in your case) means that when changing the code at some later point, you may mistakenly add a line which is handled by your existing catch block; possibly unintentionally. In your case, this is less likely because you are explicitly catching a NumberFormatException The "narrower" the responsibility of the try-catch block, the more difficult refactoring becomes. Particularly when (as in your case) you are executing a "non-local" instruction from within the catch block (the return null statement).

把它放在里面。您可以继续处理(如果您愿意)，也可以抛出一个有用的异常，告诉客户端myString的值和包含坏值的数组的索引。我认为NumberFormatException已经告诉您坏的值，但原则是将所有有用的数据放在您抛出的异常中。考虑一下在程序的调试器中，您会对什么感兴趣。

考虑:

try {
   // parse
} catch (NumberFormatException nfe){
   throw new RuntimeException("Could not parse as a Float: [" + myString + 
                              "] found at index: " + i, nfe);
} 

在需要的时候，您将非常感谢这样一个异常，其中包含尽可能多的信息。

My perspective would be try/catch blocks are necessary to insure proper exception handling, but creating such blocks has performance implications. Since, Loops contain intensive repetitive computations, it is not recommended to put try/catch blocks inside loops. Additionally, it seems where this condition occurs, it is often "Exception" or "RuntimeException" which is caught. RuntimeException being caught in code should be avoided. Again, if if you work in a big company it's essential to log that exception properly, or stop runtime exception to happen. Whole point of this description is PLEASE AVOID USING TRY-CATCH BLOCKS IN LOOPS

如果这是一个全有或全无的失败，那么第一种格式是有意义的。如果希望能够处理/返回所有未失败的元素，则需要使用第二种形式。这些就是我选择方法的基本标准。就我个人而言，如果是孤注一掷，我不会使用第二种形式。