如何实现符合规则的Java全名输入与条件终止程序？

Got it, let's build this out properly. Below is a complete, commented version of the main method that meets all your requirements, plus breakdowns of the key logic:

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

public class FullNameInput {
    public static void main(String[] args) { 
        Scanner keyboard = new Scanner(System.in); 
        System.out.println("Enter up to 10 full names with up to 120 characters and at least two names with at least 4 characters each.\nEnter 'end' to stop once you've entered at least 5 valid names.");
        
        // Store all valid full names as we collect them
        ArrayList<String> validNames = new ArrayList<>();
        
        // Run until we hit 10 valid names or user terminates early (with ≥5 names)
        while (validNames.size() < 10) {
            System.out.print("\nEnter a full name (or 'end' to terminate): ");
            String input = keyboard.nextLine().trim();
            
            // Handle early termination request
            if (input.equalsIgnoreCase("end")) {
                if (validNames.size() >= 5) {
                    System.out.println("Terminating program early. You've entered enough valid names.");
                    break;
                } else {
                    System.out.println("Error: You need at least 5 valid names before you can terminate. Keep going!");
                    continue;
                }
            }
            
            // First check: full name length can't exceed 120 characters
            if (input.length() > 120) {
                System.out.println("Error: Full name is too long! Max 120 characters allowed. Try again.");
                continue;
            }
            
            // Split name into individual parts (handles multiple spaces between names)
            String[] nameParts = input.split("\\s+");
            int longNameCount = 0;
            
            // Count how many name parts are 4+ characters long
            for (String part : nameParts) {
                if (part.length() >= 4) {
                    longNameCount++;
                }
            }
            
            // Second check: at least two parts meet the 4+ character requirement
            if (longNameCount >= 2) {
                validNames.add(input);
                System.out.printf("Success! Added valid name. You've entered %d out of 10.%n", validNames.size());
            } else {
                System.out.println("Error: Full name needs at least two names with 4+ characters. Try again.");
            }
        }
        
        // Wrap up by showing all collected valid names
        System.out.println("\nProgram finished. Here are your valid full names:");
        for (int i = 0; i < validNames.size(); i++) {
            System.out.printf("%d. %s%n", i + 1, validNames.get(i));
        }
        
        keyboard.close();
    }
}

Key Logic Breakdown: #

• Early Termination Guard: We check for "end" first, but only allow it if the user has already entered 5+ valid names—no skipping out early before meeting the minimum.
• Length Check: We reject overly long inputs immediately to avoid wasting time processing invalid entries.
• Robust Name Splitting: Using split("\\s+") ensures we handle messy input with multiple spaces (like "Jane Elizabeth Doe") without creating empty string entries.
• Long Name Validation: We count every name part that's 4+ characters long, and only accept the full name if this count hits at least 2.
• Automatic Stop: The loop will exit on its own once we hit 10 valid names, as required.

内容的提问来源于stack exchange，提问作者Ruca