No errors in Android studio, app still crashes on open

Question

So I'm incredibly new to Android studio. I typically just watch tutorials and follow along to learn what everything is and see how everything works. I was trying to follow a tutorial for a card view/recycler view with a collapsilbe toolbar, and after finishing the code (almost exactly as the guy in the video showed), the app still won't run. Only thing I changed were icon, a couple drawables and some of the values (I edited it all around in the code).

Here's the post of the source code I followed: https://github.com/delaroy/AndroidCardView?files=1

As I said, there's no errors or anything. But when I run the app, it crashes immediately.

This is also my first post, so if any other info is needed, let me know.

As I said, I changed only pictures and a few names of the variables and such. Also, everything that was changed was fixed in values and such.

I've ran other apps on my phone with no issue.

Not sure if it's a phone issue or what.

I'm using a Note 3 running Android 5.0.

Answer 1

Sometimes it occurs due to repeating of ID from xml file, example, if you have two xml files such Main activity and Home, both you have Textview with id myTextview, so once use this(id) in you class, android studio will not count as error but apps will crash at both activity once you click.' Enyoy Coding.

Answer 2

You must check the Log to see what is the exception which caused the crash. In the log (lower part of the IDE) there will be the name of the Exception, the element which launched it and also there will be the links to the lines of the code where the problem was found.

If you still can't find the error this way, you can set breakpoints at the left of the lines of code where you want the application stops during debug, and then run the app in the debug mode to see exactly what happens.

Another tip: often, when I was sure about the rightness of my code and it runs but crashes, it's about having declared all the Activities in the manifest (or all the Services) and to have set all required permission. Because in this case there are no apparent errors before running the app. Let us know!

Answer 3

Ok, it could be about Toolbar, let's see how it works.

In android is better using the widget toolbar instead of actionbar because...

To do that you must add (if there is not) the appcompact v7 library in Gradle (module:app), just like this:

dependecies {  compile 'com.android.support:appcompat-v7:+'  }

To remove the action bar and insert a toolbar you must:

 1. remove actionbar from manifest setting a no actionbar style:
     <application
          android:theme="@style/Theme.AppCompact.Light.NoActionBar"
      />

 2. insert Toolbar widget into the layout of the activity:
     <LinearLayout ...>
          ...
          <android.support.v7.widget.Toolbar
               android:id="@+id/mytoolbar"
               android:layout_width="match_parent"
               android:layout_height="?attr/actionBarSize"
               android:background="?attr/colorPrimary"
               android:elevation="8dp"
               android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
               android:popupTheme="@style/ThemeOverlay.AppCompat.Light"/>

          </LinearLayout>

 3. insert the widget into the activity and set it as support toolbar:
      @Override
     protected void onCreate(Bundle savedInstanceState){
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
           Toolbar myToolbar = (Toolbar) findViewById(R.id.mytoolbar);
           myToolbar.setLogo(R.mipmap.ic_launcher);
           myToolbar.setTitle("Titolo");
           myToolbar.setSubtitle(R.string.sottotitolo);
           setSupportActionBar(myToolbar);
     }

 4. create a menù for the Toolbar, into res>menu
 <?xml version="1.0" encoding="utf-8"?>
 <menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/new_game"
      android:icon="@drawable/ic_new_game"
      android:title="@string/new_game"
      android:showAsAction="ifRoom"/>
    <item android:id="@+id/help"
      android:icon="@drawable/ic_help"
      android:title="@string/help"
      android:showAsAction="never"/>
    <item android:id="@+id/tutorials"
      android:icon="@drawable/ic_tuts"
      android:title="@string/tutorials"
               android:showAsAction="always"/>
     </menu>

 5. bind menù to toolbar through the two methods into the activity:


@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 item selection
    switch (item.getItemId()) {
        case R.id.new_game:
            newGame();
            return true;
        case R.id.help:
            showHelp();
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}