关于Java文件单词长度统计代码的疑问（Blue J环境）

Let me break down this code for you, focusing specifically on the part you're confused about—first, let's recap what the entire method does, then dive into that final conditional block.

What the Full Method Does #

This method counts how many words in a file fall into each length category, adjusting for non-letter characters at the start or end of words (like punctuation or symbols). Here's a quick run-through of the lead-up code:

• It loops through every word in the input file with for (String word : resource.words()).
• It calculates the raw length of the word with totalLength = word.length().
• It adjusts the length if the first character isn't a letter (e.g., !Hi gets treated as length 2 instead of 3).
• It adjusts again if the last character isn't a letter and the word is longer than 1 character (e.g., Hi? becomes length 2 instead of 3; it skips this for single-character non-letters like ! to avoid negative lengths).

The Part You're Confused About: Handling the counts Array #

Let's unpack this critical code block:

if (finalLength >= counts.length) {
    counts[counts.length-1] += 1;
} else {
    counts[finalLength] += 1;
}

Core Purpose #

The counts array stores our word length totals:

• counts[0] holds the number of words with final length 0 (like single non-letter characters).
• counts[2] holds the number of words with final length 2 (like My or as).

Why the Conditional? #

Arrays in Java have a fixed length—you can't access an index outside the array's bounds (that would throw an ArrayIndexOutOfBoundsException).

Suppose your counts array has a length of 10 (so valid indices are 0 to 9). If you encounter a word with a final length of 12, you can't put it into counts[12] because that index doesn't exist.

This code solves that problem by:

1. Checking if the calculated finalLength is greater than or equal to the length of the counts array.
2. If yes: It adds that word to the last index of the array (counts.length-1). This acts as a catch-all for all words longer than the maximum index your array can handle. For example, if counts has length 10, all words with length 10 or more get counted in counts[9].
3. If no: It adds the word to the index that matches its final length (e.g., a word of length 3 goes to counts[3]).

Example Scenario #

Suppose counts is initialized as new int[6] (indices 0-5):

• A word with final length 4 → counts[4] += 1
• A word with final length 6 → since 6 >= 6, we add 1 to counts[5]
• A word with final length 10 → same as above, added to counts[5]

This way, you don't lose data for longer words, and you avoid runtime errors from invalid array indices.

内容的提问来源于stack exchange，提问作者gatete yvon