BranchingChoiceExample

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.choiceapp.MainActivity">

    <TextView
        android:id="@+id/question_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="@style/TextAppearance.AppCompat.Large"
        android:text="Hello World!"/>

    <ListView
        android:id="@+id/question_options"
        android:layout_weight="8"
        android:layout_width="match_parent"
        android:layout_height="0dp">

    </ListView>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <Button
            android:id="@+id/button_restart"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Restart"/>

        <Button
            android:id="@+id/button_back"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Back"/>

    </LinearLayout>



</LinearLayout>

MainActivity.java

package com.example.choiceapp;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Adapter;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.EnumSet;

public class MainActivity extends AppCompatActivity
{
	TextView mQuestionView;
	ListView mOptionView;
	QuestionAdapter mAdapter;
	ListAdapter mAnswerAdapater;

	Button mRestartButton;
	Button mBackButton;

	ArrayList<Question<?>> mAnsweredQuestions = new ArrayList<>();

	enum Age
	{
		CHILD,
		ADULT
	}

	enum Height
	{
		SHORT,
		NORMAL,
		TALL
	}

	enum Occupation
	{
		CHILD,
		STUDENT,
		WORKING,
		JOBLESS
	}


	//Abstract, generic class.
	//This class requires that another class extend it.
	//the T represetns another class, in our case any of the Enums
	//that provide us with the selectable options
	abstract class Question<T>
	{
		String mQuestion;
		T[] mOptions;
		Question mNext;
		T Answer;

		public Question(String question,  T... options)
		{
			mQuestion = question;
			mOptions = options;
		}

		@Override
		public String toString()
		{
			return Answer.toString();
		}

		public abstract Question getNext(int selectedOption);
	}

	///////////////
	// Age
	///////////////

	class AgeQuestion extends Question<Age>
	{
		public AgeQuestion(Age... options)
		{
			super("Are you an adult?", options );
		}

		@Override
		public Question getNext(int selectedOption)
		{
			Age option = mOptions[selectedOption];
			Answer = option;

			if (option == Age.ADULT)
			{
				//If adult, occuptation question will include these options
				return new OccupationQuestion( 	Occupation.JOBLESS,
												Occupation.STUDENT,
												Occupation.WORKING );
			}
			else
			{
				//Otherwise just child, not that it matters.
				return new OccupationQuestion( 	Occupation.CHILD );
			}
		}
	}

	///////////////
	// Occuptation
	///////////////

	class OccupationQuestion extends Question<Occupation>
	{
		public OccupationQuestion(Occupation... options)
		{
			super("What is your occuptation?", options );
		}

		@Override
		public Question getNext(int selectedOption)
		{
			Occupation option = mOptions[selectedOption];
			this.Answer = option;

			//Next question should contain all options regardless
			return new HeightQuestion( 	Height.SHORT,
										Height.NORMAL,
										Height.TALL );

		}
	}

	///////////////
	// Height
	///////////////

	class HeightQuestion extends Question<Height>
	{
		public HeightQuestion(Height... options)
		{
			super("What is your height?", options );
		}

		@Override
		public Question getNext(int selectedOption)
		{
			Height option = mOptions[selectedOption];
			this.Answer = option;

			//Last question, return null to indicate end.
			return null;
		}
	}

	private class QuestionAdapter extends BaseAdapter
	{
		Question mQuestion;

		QuestionAdapter(){};


		public void setQuestion(Question question)
		{
			mQuestion = question;
			notifyDataSetChanged();
		}

		public Question getQuestion()
		{
			return mQuestion;
		}

		@Override
		public int getCount()
		{
			if (mQuestion == null)
				return 0;

			return mQuestion.mOptions.length;
		}

		@Override
		public Object getItem(int position)
		{
			return mQuestion.mOptions[position];
		}

		@Override
		public long getItemId(int position)
		{
			return 0;
		}

		@Override
		public View getView(final int position, View convertView, ViewGroup parent)
		{
			if (convertView == null)
				convertView = new Button(parent.getContext());
			((Button)convertView).setText( mQuestion.mOptions[position].toString() );	//Just using toString of enum for simplciity

			convertView.setOnClickListener(new View.OnClickListener()
			{
				@Override
				public void onClick(View v)
				{

					Question question = mAdapter.getQuestion();
					mAnsweredQuestions.add( question );
					MainActivity.this.setupQuestion( question.getNext( position ) );

				}
			});

			return  convertView;
		}
	}

	private void displayAnswers()
	{
		String[] answers = new String[mAnsweredQuestions.size()];
		for (int i = 0; i < mAnsweredQuestions.size(); i++)
		{
			answers[i] = mAnsweredQuestions.get(i).toString();
		}
		mAnswerAdapater = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, answers);
		mOptionView.setAdapter(mAnswerAdapater);

		mBackButton.setEnabled(false);
	}

	private void setupQuestion( Question ques )
	{
		if (ques == null)
		{
			//All done, display answers
			displayAnswers();
			return;
		}

		mQuestionView.setText(ques.mQuestion);
		mAdapter.setQuestion( ques);

	}

	void displayPreviousQuestion()
	{
		if (mAnsweredQuestions.isEmpty())
			return;
		Question prevQuestion = mAnsweredQuestions.remove(  mAnsweredQuestions.size() -1 );
		setupQuestion(prevQuestion);
	}

	void startQuestions()
	{
		mAnsweredQuestions.clear();
		mAdapter = new QuestionAdapter();
		mOptionView.setAdapter(mAdapter);
		//Display first question with these options
		setupQuestion( new AgeQuestion( Age.CHILD, Age.ADULT) );

		mBackButton.setEnabled(true);
	}

	@Override
	protected void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		mQuestionView = findViewById(R.id.question_text);
		mOptionView = findViewById(R.id.question_options);

		mBackButton = findViewById(R.id.button_back);
		mRestartButton = findViewById(R.id.button_restart);


		mBackButton.setOnClickListener(new View.OnClickListener()
		{
		@Override
		public void onClick(View v)
		{
			displayPreviousQuestion();
		}
		});

		mRestartButton.setOnClickListener(new View.OnClickListener()
		{
			@Override
			public void onClick(View v)
			{
				startQuestions();
			}
		});


		//Display first question
		startQuestions();
	}
}