Java技术问题：数组元素长度校验与全名输入逻辑实现

Hey there! Let's break down your two Java questions with practical, easy-to-follow solutions.

There are a couple of straightforward ways to handle this, depending on your performance needs and code style.

方法1：用HashSet高效检测（推荐） #

This method uses a HashSet to track the lengths of elements as we iterate through the array. Since HashSet doesn't allow duplicates, if we try to add a length that's already present, we know we've found our match. It runs in O(n) time, which is great for larger arrays.

import java.util.HashSet;
import java.util.Set;

public class DuplicateLengthChecker {
    public static boolean hasDuplicateLength(String[] arr) {
        Set<Integer> lengthTracker = new HashSet<>();
        for (String element : arr) {
            int len = element.length();
            // add() returns false if the length is already in the set
            if (!lengthTracker.add(len)) {
                return true;
            }
        }
        return false;
    }
}

方法2：双重循环暴力比较 #

If you don't want to use a collection (maybe for super small arrays), you can compare each element's length with every other element. Just note this runs in O(n²) time, so it's not ideal for big datasets.

public class DuplicateLengthChecker {
    public static boolean hasDuplicateLength(String[] arr) {
        for (int i = 0; i < arr.length; i++) {
            int currentLen = arr[i].length();
            for (int j = i + 1; j < arr.length; j++) {
                if (currentLen == arr[j].length()) {
                    return true;
                }
            }
        }
        return false;
    }
}

Let's build out this feature with all your requirements in mind—input handling, validation rules, and storing the split name arrays. Here's a complete, commented implementation:

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class FullNameManager {
    public static void main(String[] args) {
        Scanner inputScanner = new Scanner(System.in);
        List<String[]> validNamesList = new ArrayList<>(); // Stores split arrays of valid full names

        System.out.println("Enter full names (type 'fim' to stop):");

        while (true) {
            // Stop if we hit the 10 valid names limit
            if (validNamesList.size() >= 10) {
                System.out.println("Maximum 10 valid names reached. Stopping input.");
                break;
            }

            String userInput = inputScanner.nextLine().trim();

            // Handle termination with "fim"—make sure we have at least 5 valid names first
            if ("fim".equalsIgnoreCase(userInput)) {
                if (validNamesList.size() < 5) {
                    System.out.println("You need at least 5 valid names. Please keep entering.");
                    continue;
                }
                break;
            }

            // Rule 1: Full name length can't exceed 120 characters
            if (userInput.length() > 120) {
                System.out.println("Nome Inválido");
                continue;
            }

            // Split full name into parts (handles multiple spaces)
            String[] nameParts = userInput.split("\\s+");

            // Rule 2: At least two parts with length 4
            int fourLetterPartCount = 0;
            for (String part : nameParts) {
                if (part.length() == 4) {
                    fourLetterPartCount++;
                }
            }

            if (fourLetterPartCount >= 2) {
                validNamesList.add(nameParts);
                System.out.println("Valid name added.");
            } else {
                System.out.println("Nome Inválido");
            }
        }

        // Optional: Display all valid split name arrays
        System.out.println("\nAll valid split name arrays:");
        for (int i = 0; i < validNamesList.size(); i++) {
            System.out.printf("Name %d: ", i + 1);
            for (String part : validNamesList.get(i)) {
                System.out.print(part + " ");
            }
            System.out.println();
        }

        inputScanner.close();
    }
}

Key details about this implementation: #

• Uses ArrayList<String[]> to store each valid full name's split parts, making it easy to access later
• Handles edge cases: ensures we get at least 5 valid names before allowing "fim" to terminate, stops at 10 valid names
• split("\\s+") splits the full name on any number of spaces, so it works even if the user accidentally adds extra spaces
• Clearly checks both validation rules (length <=120, at least two 4-letter parts) and outputs "Nome Inválido" when either fails

内容的提问来源于stack exchange，提问作者Ruca