Java：如何将String添加到对象Arraylist？

Question

Harry Potter Which Character Are You Quiz.

So I want to take each option, and the character(s) associated with each option (below the options is each character(s) separated by a comma ex. 1.Acid Pops Neville Longbottom, 3. Bertie Bott's Every Flavour Beans Luna Lovegood Nymphadora Tonks....I want to send the option, character(s) in the main method and send it as a String to the Question class and store it in an Arraylist of type Answer not String. And in the Answer class will be passed only what the user selects so for ex. 2. Sherbert Lemons and Albus Dumbledore.

String[] questions =
{
    "Favourite sweet",
};
String [][] options =
{
    {"1.Acid Pops","2.Sherbert Lemons","3.Bertie Bott's Every Flavour Beans", 
    "4.Cake","5.Hagrid's Rock Cakes","6.Chocolate Frogs","7.Ginger Newt",
    "8.I hate sweets\n"},

    {"Neville Longbottom","Albus Dumbledore", "Luna Lovegood, Nymphadora 
    Tonks", "Dobby, Arthur Weasley", "Rubeus Hagrid",
    "Harry Potter, Ron Weasley", "Minerva McGonagall, Hermione Granger, 
     Dolores Umbridge, Sybill Trelawney", 
    "Severus Snape, Tom Riddle, Sirius Black, Bellatrix Lestrange, Draco 
     Malfoy, Lucius Malfoy"}
    };

Here is my for loop in my main method:

for (int i =0; i < questions.length; i ++){
        String aQuestion = questions[i];
        Question q = new Question(aQuestion);
        System.out.println(aQuestion);
        for(int j=0; j < options[i].length; j++){
            q.setAnswers(options[i][j], options[i+1][j]);
            System.out.println(options[i][j]);
        }
    }

Here's my Question class:

 private String question;
 public ArrayList<Answer> answers = new ArrayList<Answer>();

 public Question(String q){
    question = q;
 }

public void setAnswers(String options, String options2){
    answers.add(options);
    answers.add(options2);
} 

Sorry if this doesn't make sense. I also don't understand why you have an arraylist of type: Answer that matches a class name you have in your program. If that also makes sense.

Answer 1

Here is the problem, You cannot add anything(any other object) to your List<Answer> except for Answer objects.

See the following lines Line 1 and Line 2

public void setAnswers(String options, String options2){
    answers.add(options);    //LINE 1
    answers.add(options2);   //LINE 2
} 

Now, I am not really sure how your Answer really looks like. But if it has got something to do with the options. It can have the following constructor in Answer class

Answer(String option){
   this.option = option;
}

And you can modify your code to look something like this

public void setAnswers(String options, String options2){
    answers.add(new Answer(options));    //LINE 1
    answers.add(new Answer(options));   //LINE 2
} 

Answer 2

I also don't understand why you have an arraylist of type

Collections in java were made typed to avoid accidental addition of wrong object to it. You can very well omit the type from the declaration but that is not recommended.

As an alternative solution you can either:

1. Change the type of ArrayList<Answer> answers to more generic one like Serializable or,
2. Wrap String options1 and options2 and convert them into Answer type and then add them to list.

I'll prefer second option.

Convert: Create a method in Answer class which return Answer object, you can make it static

public static Answer getAnswerFromString(String answer) {
  // Logic to create Answer object from string
}

Then modify this method as below to add answer to the list:

public void setAnswers(String options, String options2){
  answers.add(Answer.getAnswerFromString(options));
  answers.add(Answer.getAnswerFromString(options2));
}

Or you can add a constructer with String parameter if it make sense as pointed in other answer.