LESSON 378 OF 410 · PROJECTS: COMMAND-LINE TOOLS

CLI Tool: wc v2 — Count Words in Java

Practice

Build a tiny version of the Unix wc -w command. Given a list of lines, return the total number of words (whitespace-separated tokens) across all lines as an integer.

Function signature:

public int countWords(List<String> lines)

Example:

Input: lines = ["hello world", "foo bar baz", ""]

Output: 5

The empty string contributes 0 words, "hello world" contributes 2, and "foo bar baz" contributes 3. Total: 5.

Words are separated by one or more spaces or tabs, and leading or trailing whitespace is ignored. A line with no words (empty, or only whitespace) contributes 0, and an empty list of lines gives 0. The input is plain ASCII text.

Iterate over the lines and accumulate the word count. Java's String.split("\\s+") on an empty/whitespace-only line still returns an array of length 1 — so handle the empty case explicitly.

Trim the line, skip it if it's empty, otherwise split:

String trimmed = line.trim();
if (trimmed.isEmpty()) continue;
total += trimmed.split("\\s+").length;

The full solution:

class Solution {
    public int countWords(List<String> lines) {
        int total = 0;
        for (String line : lines) {
            String trimmed = line.trim();
            if (trimmed.isEmpty()) continue;
            total += trimmed.split("\\s+").length;
        }
        return total;
    }
}

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CLI Tool: wc v2 — Count Words in Java

Wc V2 in Java