Develop Reference

How can i randomize question in a quiz app

I made a simple quiz on Android Studio which contains 3+ questions. How to make the questions become random without duplicated. This app does not use a database. I'm new to programming so I don't know what to do about this
MainActivity.java
import androidx.appcompat.app.AppCompatActivity;
import android.app.AlertDialog; import android.graphics.Color; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.TextView;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
TextView totalQuestionsTextView;
TextView questionTextView;
Button ansA,ansB,ansC,ansD;
Button submitBtn;
int score=0;
int totalQuestions = QuestionAnswer.question.length;
int currentQuestionIndex = 0;
String selectedAnswer = "";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
totalQuestionsTextView = findViewById(R.id.total_questions);
questionTextView = findViewById(R.id.question);
ansA = findViewById(R.id.ans_A);
ansB = findViewById(R.id.ans_B);
ansC = findViewById(R.id.ans_C);
ansD = findViewById(R.id.ans_D);
submitBtn = findViewById(R.id.submbit_btn);
ansA.setOnClickListener(this);
ansB.setOnClickListener(this);
ansC.setOnClickListener(this);
ansD.setOnClickListener(this);
submitBtn.setOnClickListener(this);
totalQuestionsTextView.setText("Total Questions : "+totalQuestions);
loadNewQuestion();
}
#Override
public void onClick(View view) {
ansA.setBackgroundColor(Color.WHITE);
ansB.setBackgroundColor(Color.WHITE);
ansC.setBackgroundColor(Color.WHITE);
ansD.setBackgroundColor(Color.WHITE);
Button clickedButton = (Button) view;
if(clickedButton.getId()==R.id.submbit_btn){
currentQuestionIndex++;
loadNewQuestion();
}else{
//choices button clicked
selectedAnswer = clickedButton.getText().toString();
clickedButton.setBackgroundColor(Color.MAGENTA);
}
}
void loadNewQuestion(){
if(currentQuestionIndex == totalQuestions){
finishQuiz();
return;
}
questionTextView.setText(QuestionAnswer.question[currentQuestionIndex]);
ansA.setText(QuestionAnswer.choices[currentQuestionIndex][0]);
ansB.setText(QuestionAnswer.choices[currentQuestionIndex][1]);
ansC.setText(QuestionAnswer.choices[currentQuestionIndex][2]);
ansD.setText(QuestionAnswer.choices[currentQuestionIndex][3]);
}
void finishQuiz(){
String passStatus = "";
if (score > totalQuestions*0.60){
passStatus = "Passes";
}else{
passStatus = "Failed";
}
new AlertDialog.Builder(this)
.setTitle(passStatus)
.setMessage("Score is "+score+" out of "+ totalQuestions)
.setPositiveButton("Restart",(dialogInterface, i) -> restartQuiz())
.setCancelable(false)
.show();
}
void restartQuiz(){
score = 0;
currentQuestionIndex = 0;
loadNewQuestion();
}
QuestionAnswer.java
import java.util.Arrays; import java.util.List; import java.util.Random;
public class QuestionAnswer {
public static String[] question = {
"Which company own the android?",
"Which one is not the programming language?",
"Where are you watching this video"
};
public static String choices[][] = {
{"Google", "Apple", "Nokia", "Samsung"},
{"Java", "Kotlin", "Notepad", "Python"},
{"Facebook", "Whatsapp", "Instagram", "Youtube"},
};
public static String correctAnswers[] = {
"Google",
"Notepad",
"Youtube"
};
}
how can i add shuffle.collection or random to make my app show random question instead

You need to find out about Random class first in Java. Thereafter, you will create a random number using Random class in onClick function, then set a question's index to your Random number

Passing data always comes back 0

I have fixed the problem that I originally create this question for, but now I have a new problem. The activity gets created and it goes to my other screen when I select the button, but now the value that is suppose to get passed to the second activity always comes back as 0.
I am assuming this is the line that is causing it? How, would I fix that?
int goal = intent.getIntExtra("calorieGoal", 0);
My Main Activity.java
package net.androidbootcamp.myapplication;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
public class MainActivity extends AppCompatActivity {
String selection;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//gets data from the user input
final EditText weight = (EditText)findViewById(R.id.bodyWeight);
final EditText age = (EditText)findViewById(R.id.yearsOld);
final EditText height = (EditText)findViewById(R.id.inchHeight);
//gets the spinner selection
final Spinner activityLevel = (Spinner)findViewById(R.id.activityLevel);
//initate the button, and set code for when the button is clicked
Button lose = (Button)findViewById(R.id.loseButton);
lose.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String userWeight = weight.getText().toString();
String userheight = height.getText().toString();
String userAge = age.getText().toString();
int uWeight = Integer.parseInt(userWeight);
int uHeight = Integer.parseInt(userheight);
int uAge = Integer.parseInt(userAge);
double calorieGoal;
selection = activityLevel.getSelectedItem().toString();
if(selection == "sedentary"){
double bmr = 66.47 + (6.24 * uWeight) + (12.7 * uHeight) - (6.75 * uAge);
calorieGoal = bmr * 1.2;
Intent intent = new Intent(MainActivity.this, Gain_Activity.class);
intent.putExtra("calorieGoal", calorieGoal);
startActivity(intent);
}
}
});
}
}
second activity that I am trying to send the data to
package net.androidbootcamp.myapplication;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
public class Gain_Activity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_gain_);
Intent intent = getIntent();
int goal = intent.getIntExtra("calorieGoal", 0);
TextView texview = findViewById(R.id.calorieGoal);
texview.setText(goal);
}
}

calorieGoal is of type double, not int. You will not be able to get it via getIntExtra.
Try getDoubleExtra.

Closing Android Game After 5 Seconds

I'm tring to build an simple android game.
Users answer the questions, when the answer is correct, it is continue..
I want to add time control for each answer.
I tried to add handler function, but I didn't.
My Code;
import java.util.Collections;
import java.util.Arrays;
import java.util.List;
import java.util.Random;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class EasyGameActivity extends Activity {
public int score = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_easygame);
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
public void run() {
finishScreen();
}
}, 5000);
startGame();
}
private void startGame() {
// TODO Auto-generated method stub
Button b1 = (Button)findViewById(R.id.answer_one);
Button b2 = (Button)findViewById(R.id.answer_two);
Button b3 = (Button)findViewById(R.id.answer_three);
Button b4 = (Button)findViewById(R.id.answer_four);
Random number = new Random();
int first = number.nextInt(100)+1;
int second = number.nextInt(100)+1;
int answer = first + second;
int rnd1 = answer + 1;
int rnd2 = answer + 2;
int rnd3 = answer - 1;
final String a = Integer.toString(answer);
String b = Integer.toString(rnd1);
String c = Integer.toString(rnd2);
String d = Integer.toString(rnd3);
((TextView) findViewById(R.id.display)).setText(Integer.toString(first) + '+' + Integer.toString(second));
List<Button> buttons = Arrays.asList(b1, b2, b3, b4);
List<String> texts = Arrays.asList(a, b, c, d);
Collections.shuffle(texts);
int i = 0;
OnClickListener onClick = new OnClickListener() {
public void onClick(View view) {
Button button = (Button) view;
String value = (String) button.getText();
if(value == a) {
checkTrue();
} else {
finishScreen();
}
}
};
for(Button button : buttons) {
button.setText(texts.get(i++));
button.setOnClickListener(onClick);
}
}
private void checkTrue() {
score++;
((TextView) findViewById(R.id.score)).setText(Integer.toString(score));
startGame();
}
private void finishScreen() {
score = 0;
startActivity (new Intent("com.bsinternet.mathfast.RESTARTGAMESCREEN"));
finish();
}
}
How can I add time control. Thanks.

This bit of code doesn't look right
if(value == a) {
checkTrue();
} else {
finishScreen();
}
You should be using equals() to check for String equality. At the moment you are checking only object equality, which will evaluate to False, and the code will never call checkTrue().
Do this instead:
if(value.equals(a) {
checkTrue();
} else {
finishScreen();
}

Android list view current position doesn't work properly

I'm Getting data from my database and pushing them into ListView to view all the data.
Inside my ListView I also have a TextView with the text "Like" in it. Now when I click the like text it will change to "Liked" and I'm updating my like status in my database.
Now my problem is that when i click the "Like" text, the text changes to "Liked" and also it is updated in DB. But also when I scroll through the List View, I can notice other lists' Like text is also changed to Liked. I'm not sure what's going wrong.
I've been trying to get around this problem for quite some days but had no success.
This is my adapter code. At the bottom you can see my onClickListener for the textview
package com.mytestapp.myapp;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebView;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class ForumAdapter extends ArrayAdapter<DiscussionList> {
private static List<DiscussionList> items = null;
public ForumAdapter(Context context, List<DiscussionList> items) {
super(context, R.layout.custom_list, items);
this.items = items;
}
#Override
public int getCount() {
return items.size();
}
public static DiscussionList getModelPosition(int position) {
return items.get(position);
}
public void refill(List<DiscussionList> items) {
items.clear();
items.addAll(items);
notifyDataSetChanged();
}
public static class ViewHolder {
WebView mywebviewholder;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
View v = convertView;
if (v == null) {
LayoutInflater li = LayoutInflater.from(getContext());
v = li.inflate(R.layout.custom_list, null);
} else {
holder = (ViewHolder) convertView.getTag();
}
DiscussionList app = items.get(position);
if (app != null) {
TextView titleText = (TextView) v.findViewById(R.id.dscTitle);
TextView categoryText = (TextView) v.findViewById(R.id.dscCategory);
TextView descriptionText = (TextView) v
.findViewById(R.id.dscDescription);
TextView timeText = (TextView) v.findViewById(R.id.dscTime);
TextView idText = (TextView) v.findViewById(R.id.dscDiscId);
final TextView likeText = (TextView) v.findViewById(R.id.likeText1);
String like_Status = app.getLikeStatus();
titleText.setText(app.getTitle());
categoryText.setText(app.getCategory());
descriptionText.setText(app.getDescription());
timeText.setText(app.getTime());
idText.setText(app.getDiscId());
if (like_Status == "null") {
likeText.setText("Like");
} else {
likeText.setText("Liked");
}
final String dId = app.getDiscId();
// onClick for image button inside list view
likeText.setTag(new Integer(position));
likeText.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
final Integer myposition = (Integer) view.getTag();
// Toast.makeText(getContext(), "" + dId,
// Toast.LENGTH_SHORT)
// .show();
likeText.setText("Liked");
MainActivity val = new MainActivity();
val.updateLikeTable(dId);
}
});
}
return v;
}
}
And also this is my MainActivity.java file where i update the likes in database
package com.mytestapp.myapp;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.os.StrictMode;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.Toast;
public class MainActivity extends ListActivity implements FetchDataListener {
public static String strTitle = "0", strCategory = "0",
strDescription = "0", strTime = "0", strDid = "0";
Collegemate_DB db = new Collegemate_DB(this);
int likeStatus = 1;
private ProgressDialog dialog;
public static String usId=null;
ImageButton imgButton;
List<DiscussionList> items = new ArrayList<DiscussionList>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_forum_topics);
usId = db.getCurrentuserId();
initView();
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
.permitAll().build();
StrictMode.setThreadPolicy(policy);
}
/*
* On click listener to get values from DiscussionList class and send it
* to another activity when clicking on the list item
*/
ListView forumList = getListView();
forumList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// Get position of the clicked list item from adapter
String dTitle, dCategory, dDescription, dTime, dDid;
DiscussionList accessVar = ForumAdapter
.getModelPosition(position);
dTitle = accessVar.getTitle();
dCategory = accessVar.getCategory();
dDescription = accessVar.getDescription();
dTime = accessVar.getTime();
dDid = accessVar.getDiscId();
/*
* Storing the forum values in string and passing it to another
* activity
*/
String values[] = { dTitle, dCategory, dDescription, dTime,
dDid };
Intent i = new Intent(MainActivity.this, ForumFullView.class);
i.putExtra("sendData", values);
startActivity(i);
}
});
}
private void initView() {
// show progress dialog
Log.i("j","Inside Init");
dialog = ProgressDialog.show(this, "", "Loading...");
String url = "http://example.com/mypath/listData.php?currentUser_id="
+ usId;
Log.i("Fetch Url : ", url);
FetchDataTask task = new FetchDataTask(this);
task.execute(url);
}
#Override
public void onFetchComplete(List<DiscussionList> data) {
// dismiss the progress dialog
if (dialog != null)
dialog.dismiss();
// create new adapter
ListView forumList = getListView();
// set the adapter to list
ForumAdapter adapter = new ForumAdapter(this, data);
if (forumList.getAdapter() == null) {
//final ForumAdapter adapter = new ForumAdapter(this, data);
forumList.setAdapter(adapter);
} else {
((ForumAdapter) forumList.getAdapter()).refill(items);
}
// setListAdapter(adapter);
}
#Override
public void onFetchFailure(String msg) {
// dismiss the progress dialog
if (dialog != null)
dialog.dismiss();
// show failure message
Toast.makeText(this, msg, Toast.LENGTH_LONG).show();
}
public void updateLikeTable(String dId,List<DiscussionList> items) {
try {
String likeUrl = "http://example.com/mypath/createlike.php?discId="
+ dId + "&userId=" + usId + "&like_status=" + likeStatus;
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet();
request.setURI(new URI(likeUrl));
client.execute(request);
} catch (Exception e) {
e.printStackTrace();
}
}
}
Any help is appreciated.
Thanks in advance

The problem you're having is that the ListView widget recycles its views if it can. Once a view is off the screen from scrolling, it goes onto a garbage heap so that when a new view scrolls into place it can be reused, rather than requiring a fresh one to be inflated from scratch. That recycled view is the convertView parameter in the getView() method. When your ListView is first populating, convertView will always be null, since the garbage pile has nothing in it, so you're forced to inflate new views, but subsequent calls will likely have that parameter as non-null.
The practical result of this is that when a clicked view that's been set to "Liked" gets recycled, the TextView is still there and still populated with "Liked" rather than the presumed default of "Like". So if you click a view, then scroll down so it goes off the screen, it'll come back around and cause the bug you're seeing.
What you'll probably want to do to fix this is to set the text of likeText within getView() every time, based on what it is in your database. If the post has been liked, set it to "Liked", and if it hasn't, set it to "Like". It should just be one more line, assuming you have easy access to whether or not the post is liked from your DiscussionList object.
P.S. As a side note, hard-coded strings are typically frowned upon in Android, so you may want to move your "Liked" string into the resource files. It's not really necessary unless you're planning to do translations, but it's still good practice.

Android passing value from checkbox to toast view

I managed to do the passing value from radio button and now I want when the user clicks on several checkboxes to display the checked values in a toast view +Toppings: HERE
package com.example.pizzaorderding;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final EditText name=(EditText)findViewById(R.id.name);
final EditText phone=(EditText)findViewById(R.id.phone_number);
final EditText address=(EditText)findViewById(R.id.address);
final RadioGroup shapes = (RadioGroup) findViewById(R.id.rBtnshapes);
final RadioGroup types = (RadioGroup) findViewById(R.id.rBtntypes);
final CheckBox pep = (CheckBox)findViewById(R.id.pepperoni);
final CheckBox mshr = (CheckBox)findViewById(R.id.mushrooms);
Button orderBtn = (Button)findViewById(R.id.orderBtn);
orderBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
StringBuffer result = new StringBuffer();
result.append("Pepperoni").append(pep.isChecked());
result.append("Mushrooms").append(mshr.isChecked());
int selectedShape = shapes.getCheckedRadioButtonId();
int selectedCheese = types.getCheckedRadioButtonId();
RadioButton sh = (RadioButton)findViewById(selectedShape);
RadioButton ty=(RadioButton)findViewById(selectedCheese);
Toast.makeText(MainActivity.this, "Name: "+name.getText()+"\n"+"Phone: "+phone.getText()+"\n"+"Address: " +address.getText()+"\n"+"Shape: "+sh.getText()+"\n"+"Cheese: "+ty.getText()+"\n"+"Toppings: "+result.toString(), Toast.LENGTH_SHORT).show();
}
});
}
}

Maybe this will work?
result.append("Pepperoni").append(pep.isChecked().toString());
result.append("Mushrooms").append(mshr.isChecked().toString());

Do you mean something like:
if (pep.isChecked())
result.append("Pepperoni, ");
if (mshr.isChecked())
result.append("Mushrooms, ");
if (result.length() > 2)
result.delete(result.length() - 2, result.length()); // to remove last ", "

public void onClick(View v) {
// TODO Auto-generated method stub
StringBuffer result = new StringBuffer();
result.append("Pepperoni"+"\n").append(pep.isChecked()).toString();
result.append("Mushrooms"+"\n").append(mshr.isChecked()).toString();
int selectedShape = shapes.getCheckedRadioButtonId();
int selectedCheese = types.getCheckedRadioButtonId();
RadioButton sh = (RadioButton)findViewById(selectedShape);
RadioButton ty=(RadioButton)findViewById(selectedCheese);
Toast.makeText(MainActivity.this, "Name: "+name.getText()+"\n"+"Phone: "+phone.getText()+"\n"+"Address: " +address.getText()+"\n"+"Shape: "+sh.getText()+"\n"+"Cheese: "+ty.getText()+"\n"+"Toppings: "+result.toString(), Toast.LENGTH_SHORT).show();
`
And that is how it displays http://postimg.org/image/zc1dobpuf/ .. I dont want to display true or false, just if it's checked to display the topping