IllegalargumentException while making a custom toast in android

Question

I am very new to android. I am making a custom toast but by app is crashing just after the toast appears in the screen. This is my mainactivity.java -

public class MainActivity extends Activity {
    int counter = 0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }   

    public void dosome(View V) {
        Log.d("message","a message");



        if(V.getId() == R.id.launchmap) {
            Toast toast = new Toast(this);
            toast.setGravity(Gravity.BOTTOM, 0, 0);
            toast.setDuration(Toast.LENGTH_LONG);

            LayoutInflater inflater = getLayoutInflater();
            View appear = inflater.inflate(R.layout.toast_layout,(ViewGroup)findViewById(R.id.root),true);
            toast.setView(appear);
            toast.show();
        }
    }

}   

And these are my xml files.

toast_layout.xml -

<?xml version="1.0" encoding="utf-8"?>
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
   android:id="@+id/imageView1"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:src="@drawable/images" />

activity_main.xml -

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:id="@+id/root"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/launchmarket"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="dosome"
        android:text="launchmarket" />

    <Button
        android:id="@+id/launchmap"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="dosome"
        android:text="launchmap" />

</LinearLayout>

However, in the inflater.inflate, if i pass the 3rd parameter as false, everything works. Why so?

Answer 1

Thing is toast is not supposed to be child of some layout in your view, its an independent layout. This is the layout of your toast (toast_layout.xml in your case).

<?xml version="1.0" encoding="utf-8"?>
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
   android:id="@+id/imageView1"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:src="@drawable/images" />

You need to wrap this with a layout lets say a LinearLayout and give id toast_layout_root for that particular linearLayout. Like so

<?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:id="@+id/toast_layout_root">

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/images" />
</LinearLayout>

Then do this while making your Toast

View appear = inflater.inflate(R.layout.toast_layout,(ViewGroup)findViewById(R.id.toast_layout_root),true);

What you are doing currently is trying attach toast to the linearlayout that is in your activity. Toasts have to be independent.