Simple java questionnaire using json-CodePudding

I made a simple questionnaire. I need to write the responses to a JSON file. How to do it? I use IDEA Intellij and library GSON for work with JSON. This is main class "Quiz":

package questions;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import com.google.gson.GsonBuilder;
import java.io.FileWriter;
import java.io.IOException;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Scanner;

public class Quiz {
    public static <Outfile> void main(String[] args) throws IOException {

        String userJson = "[{\"question\": \"1.What is your marital status?\", \"a\": \"(a)Single\", \"b\": \"(b)Married\"},"  
                "{\"question\": \"2.Are you planning on getting married next year?\", \"a\": \"(a)Yes\", \"b\": \"(b)No\"}," 
                "{\"question\": \"3.How long have you been married?\", \"a\": \"(a)Less than a year\", \"b\": \"(b)More than a year\"}," 
                "{\"question\": \"4.Have you celebrated your one year anniversary?\", \"a\": \"(a)Yes\" , \"b\": \"(b)No\"}]";

        Gson gson = new Gson();
        Type questionListType = new TypeToken<ArrayList<Question>>(){}.getType();

        ArrayList<Question> questionArray = gson.fromJson(userJson, questionListType);

        FileWriter fileWriter = new FileWriter("answer.json");


        for(Question question : questionArray) {
            System.out.println("Question:"   question.question);
            System.out.println("Answer:"   question.a   "   "   question.b);
            Scanner keyboardInput = new Scanner(System.in);
            String answer = keyboardInput.nextLine();
            System.out.println("You got: "   answer);

        }
        
    }}

This is class "Question":

package questions;
public class Question {

    public String question;
    public String a;
    public String b;

    public String getQuestion() {
        return question;
    }
    public void setQuestion(String question) {
        this.question = question;
    }

    public String getA() {
        return a;
    }
    public void setA(String a) {
        this.a = a;
    }

    public String getB() {
        return b;
    }
    public void setAnswer2(String b) {
        this.b = b;
    }
  }

I'm trying to use FileWriter, but I'm doing it wrong. The output file is empty. Help me, pls.

CodePudding user response：

You have created a FileWriter, but you are never actually writing anything to the file. This is why the file is empty.

  string jsonData = "{}";
  FileWriter output = new FileWriter("answer.json");
  // Writes the string to the file
  output.write(jsonData);

  // Closes the writer
  output.close();

This would allow you to write contents to a file. Make sure to call close() on the FileWriter after writing your content. After that your file answer.json should contain:

{}

CodePudding user response：

@Test
public void test1() {
    try {
        String userJson = "[{\"question\": \"1.What is your marital status?\", \"a\": \"(a)Single\", \"b\": \"(b)Married\"},"  
                "{\"question\": \"2.Are you planning on getting married next year?\", \"a\": \"(a)Yes\", \"b\": \"(b)No\"},"  
                "{\"question\": \"3.How long have you been married?\", \"a\": \"(a)Less than a year\", \"b\": \"(b)More than a year\"},"  
                "{\"question\": \"4.Have you celebrated your one year anniversary?\", \"a\": \"(a)Yes\" , \"b\": \"(b)No\"}]";

        JSONArray jsonArray = JSON.parseArray(userJson);
        System.out.println(jsonArray);
        List<Question> javaList = jsonArray.toJavaList(Question.class);
        writeToFile(javaList);
    } catch (Exception e) {
        e.printStackTrace();
    }


}

private void writeToFile(List<Question> data) throws Exception {
    BufferedWriter bw;
    try {
        bw = new BufferedWriter(new FileWriter("D:\\test.txt"));
        for (int i = 0; i < data.size(); i  ) {
            bw.write(JSON.toJSONString(data.get(i)));
            bw.newLine();
            bw.flush();
        }
        bw.close();
    } catch (Exception e) {
        throw e;
    }
}