如何在Java中用新行分割每个输入？

Question

I'm trying get 5 string inputs from the user and those inputs are going to be stored in an array. When I enter something like "Hello World" and hit a new line I can only enter 3 more words. So I want each user input to be a sentence and hitting enter should ask the user for another input on a new line.

Here is my code so far:

Scanner user_input = new Scanner(System.in);   
String ask1 = user_input.next()+"\n";
String ask2 = user_input.next()+"\n";
String ask3 = user_input.next()+"\n";
String ask4 = user_input.next()+"\n";
String ask5 = user_input.next();
String[] cars = {ask1, ask2, ask3, ask4, ask5};    

Answer 1

According to the documentation , Scanner.next() :

Finds and returns the next complete token from this scanner. A complete token is preceded and followed by input that matches the delimiter pattern.

As the default delimiter used by Scanner is whitespace, calling next() will get you individual words from user input. When you want to capture multiple words that end with a newline, you should use Scanner.nextLine() instead.

Additionally, you can remove code duplication (which you always should do, keeping things DRY ) by creating the array beforehand and allocating the user input entries within a loop:

final int numberOfCars = 5;
Scanner userInput = new Scanner(System.in);   
String[] cars = new String[numberOfCars];

for (int i = 0; i < numberOfCars; i++) {
    cars[i] = userInput.nextLine();
}

Answer 2

I recommend that you have a certain keyword or phrase that the user can type which stops the program. Here, I made a simple program that uses the java.util.Scanner object to receive keyboard input. Each value is stored in a java.util.ArrayList called "inputs." When the user is done entering input, he/she will type "stop" and the program will stop.

import java.util.*; //you need this for ArrayList and Scanner

public class Input{

    public static void main(String[] args){

        Scanner user_input = new Scanner(System.in); //create a scanner object
        ArrayList<String> inputs = new ArrayList<String>(); //I used a java.util.ArrayList simply because it is more flexible than an array
        String temp = ""; //create a temporary string which will represent  the current input string

                while(!((temp = user_input.next()).equals("stop"))){ //set temp equal to the  new input each iteration
                inputs.add(temp); //add the temp string to the arraylist
                }
    }
}

If you want to convert the ArrayList to a normal String[], use this code:

String[] inputArray = new String[inputs.size];
for(int i = 0; i < inputs.size(); i++){
    inputArray[i] = inputs.get(i);
} 

Answer 3

You can make this more generic by storing your question on an array and looping through a for loop prompting for input until you have question. This why when you have more questions you can add them to list without changing anything else on the code.

Then, to answer your original question regarding creating a String array, you could use following method String[] a = answers.toArray(new String[answers.size()]);

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

public class HelloWorld
{
  public static void main(String[] args)
  {
    ArrayList<String> questions = new ArrayList<String>(5){{
        add("What is your name?");
        add("What is school you went to?");
        add("Do you like dogs?");
        add("What is pats name?");
        add("Are you batman?");
    }};

    ArrayList<String> answers = new ArrayList<String>(questions.size()); // initialize answers with the same size as question array
    String input = ""; // Stores user input here
    Scanner scanner = new Scanner(System.in);
    for(String question : questions){
      System.out.println(question); // Here we adding a new line and the user type his answer on a new line
      input = scanner.nextLine();
      answers.add(input); // Store the answer on answers array
    }
    System.out.println("Thank you.");
    String[] a = answers.toArray(new String[answers.size()]); // THis converts ArrayList to String[]
    System.out.println("You entered: " + a.toString());
  }
}

Answer 4

You want this instead:

Scanner user_input = new Scanner(System.in);   
String ask1 = user_input.nextLine()+"\n";
String ask2 = user_input.nextLine()+"\n";
String ask3 = user_input.nextLine()+"\n";
String ask4 = user_input.nextLine()+"\n";
String ask5 = user_input.nextLine();
String[] cars = {ask1, ask2, ask3, ask4, ask5};