how to get next item in ArrayList in java

Issue

i followed a YouTube tutorial about programming a quiz app using java android studio in the tutorial you put the question in array list then you get randomly question from it this can cause a problem of getting the same question many time. How can i fix that? i thought about instead of using random i use a function to get the next item in the list but it didn't work for me. Yhis is my code

package com.example.quiz20;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.google.android.material.bottomsheet.BottomSheetDialog;

import java.util.ArrayList;
import java.util.Random;

public class MainActivity extends AppCompatActivity {
    private TextView questionTV,questionNumberTV;
    private Button option1Btn,option2Btn,option3Btn,option4Btn;
    private ArrayList<QuizModel> quizModelArrayList;
    Random random;
    int currentScore = 0 , questionAttempted = 0, currentPos;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        questionTV= findViewById(R.id.idTVQuestion);
        questionNumberTV=findViewById(R.id.idTVQuestionAttempted);
        option1Btn=findViewById(R.id.idBtnOption1);
        option2Btn=findViewById(R.id.idBtnOption2);
        option3Btn=findViewById(R.id.idBtnOption3);
        option4Btn=findViewById(R.id.idBtnOption4);
        quizModelArrayList = new ArrayList<>();
        random = new Random();
        getQuizQuestion(quizModelArrayList);
        currentPos = random.nextInt(quizModelArrayList.size());
        setDataToViews(currentPos);
        option1Btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(quizModelArrayList.get(currentPos).getAnswer().trim().toLowerCase().equals(option1Btn.getText().toString().trim().toLowerCase())){
                    currentScore++;
                }
                questionAttempted++;
                currentPos = random.nextInt(quizModelArrayList.size());
                setDataToViews(currentPos);

            }
        });

        option2Btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(quizModelArrayList.get(currentPos).getAnswer().trim().toLowerCase().equals(option2Btn.getText().toString().trim().toLowerCase())){
                    currentScore++;
                }
                questionAttempted++;
                currentPos = random.nextInt(quizModelArrayList.size());
                setDataToViews(currentPos);
            }
        });

        option3Btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(quizModelArrayList.get(currentPos).getAnswer().trim().toLowerCase().equals(option3Btn.getText().toString().trim().toLowerCase())){
                    currentScore++;
                }
                questionAttempted++;
                currentPos = random.nextInt(quizModelArrayList.size());
                setDataToViews(currentPos);
            }
        });

        option4Btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(quizModelArrayList.get(currentPos).getAnswer().trim().toLowerCase().equals(option4Btn.getText().toString().trim().toLowerCase())){
                    currentScore++;
                }
                questionAttempted++;
                currentPos = random.nextInt(quizModelArrayList.size());
                setDataToViews(currentPos);
            }
        });

    }

    private void showBottomSheet(){
        BottomSheetDialog bottomSheetDialog = new BottomSheetDialog(MainActivity.this);
        View bottomSheetView = LayoutInflater.from(getApplicationContext()).inflate(R.layout.score_bottom_sheet,(LinearLayout)findViewById(R.id.idLLScore));
        TextView scoreTV = bottomSheetView.findViewById(R.id.idTVScore);
        Button restartQuizBtn = bottomSheetView.findViewById(R.id.idBtnRestart);
        scoreTV.setText("you score is \n"+currentScore + "/4");
        restartQuizBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                currentPos = random.nextInt(quizModelArrayList.size());
                setDataToViews(currentPos);
                questionAttempted = 0;
                currentScore = 0;
                bottomSheetDialog.dismiss();
            }
        });
        bottomSheetDialog.setCancelable(false);
        bottomSheetDialog.setContentView(bottomSheetView);
        bottomSheetDialog.show();
    }

    private void setDataToViews(int currentPos){
        questionNumberTV.setText("Question Attempted : "+questionAttempted + "/4");
        if(questionAttempted == 4){
            showBottomSheet();
        }else {
            questionTV.setText(quizModelArrayList.get(currentPos).getQuestion());
            option1Btn.setText(quizModelArrayList.get(currentPos).getOption1());
            option2Btn.setText(quizModelArrayList.get(currentPos).getOption2());
            option3Btn.setText(quizModelArrayList.get(currentPos).getOption3());
            option4Btn.setText(quizModelArrayList.get(currentPos).getOption4());
        }


    }
    private void getQuizQuestion(ArrayList<QuizModel> quizModelArrayList) {
        quizModelArrayList.add(new QuizModel("in which year google released?","1998","2000","2004","1995","1998"));
        quizModelArrayList.add(new QuizModel("What does CPU stand for?","Core Processing Unit","Central Processing Unit","Command Processing Unit","Custom Processing Unit","Central Processing Unit"));
        quizModelArrayList.add(new QuizModel("what is the name of the first internet search engine?","Google","Yahoo","AOL","Archie","Archie"));
        quizModelArrayList.add(new QuizModel("Which Programming language is the most widely used?","JavaScript","JAVA","Python","PHP","JavaScript"));

    }
}

Solution

To avoid getting the same selection multiple times, you may want to remove it from the list after it was chosen. The syntax could look something like this:

    Random rand = new Random();
    ArrayList <Type> list = new ArrayList<>();
    int selection = rand.nextInt(list.size() + 1);

    switch(selection)
    {
        case X:
            do the X stuff;
            list.remove(X);
            break;
    }

The ArrayList knows what index X is at, so calling it by name will remove the entry. Using the size of the ArrayList to create the bounds for Random numbers also helps keep it dynamic

NOTE this is NOT complete code

Information/examples about preserving contents of the ArrayList using list.clone()

https://www.tutorialspoint.com/clone-an-arraylist-in-java -- An ArrayList can be cloned using the java.util.ArrayList.clone() method. This method does not take any parameters but returns a shallow copy of the specified ArrayList instance. This means that the new ArrayList created using the ArrayList.clone() method refers to the same elements as the original ArrayList but it does not duplicate the elements.

Answered By - Kemper Lee