The android studio AVD emulator does not show my app

Question

I finished a simple app I learned how to do from "Android Programming, The Big Nerd Ranch Guide (2nd Edition)" the app does nothing but ask a question and wait for an answer and then display weather the answer is correct or not, in a toast.

So I finished the app but when I run it on the android studio AVD emulator I see nothing bu the empty home screen

I am new to android (in fact this is my first app ever) so I don't really know a lot, most of the code is auto generated but I understand some of it but I can't edit it:

Here is the xml code:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="24dp"
        android:text="@string/question_text"></TextView>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/true_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/true_button" />

        <Button
            android:id="@+id/false_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/false_button" />


    </LinearLayout>

</LinearLayout>

And here is the java code (all of it except the onCreate method is auto generated:

package com.bignerdranch.android.geoquiz;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.widget.Button;
import android.view.MenuItem;
import android.widget.Toast;

public class QuizActivity extends AppCompatActivity
{
    private Button mTrueButton;
    private Button mFalseButton;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_quiz);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View view)
            {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG).setAction("Action", null).show();
            }
        });
        mTrueButton = (Button) findViewById(R.id.true_button);
        mFalseButton = (Button) findViewById(R.id.false_button);
        mTrueButton.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                Toast.makeText(QuizActivity.this, R.string.correct_toast, Toast.LENGTH_SHORT).show();


            }
        });
        mFalseButton.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                Toast.makeText(QuizActivity.this, R.string.incorrect_toast, Toast.LENGTH_SHORT);
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item)
    {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings)
        {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

The string resource xml file:

<resources>
    <string name="app_name">GeoQuiz</string>
    <string name="action_settings">Settings</string>
    <string name="question_text">Constantinople is the largest city in Turkey.</string>
    <string name="true_button">True</string>
    <string name="false_button">False</string>
    <string name="correct_toast">Correct !</string>
    <string name="incorrect_toast">Incorrect !</string>
</resources>

And everything else is auto generated and not modefied, screenshots:

the android emulator screenshot

output screenshot

Answer 1

try starting the emulator first and then run the project. It will prompt you to choose a device since the device is up and running select it and see if it will help.