Android custom LinearLayout not appearing

Question

I'm facing problems when creating custom LinearLayout

I have defined my custom layout in xml as follows

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
android:gravity="center_horizontal">

<TextView
    android:id="@+id/textViewIcon"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textSize="48sp"
    android:text="abc" />

<TextView
    android:id="@+id/textViewMessage"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textSize="24sp"
    android:text="abc" />

<Button
    android:id="@+id/btnAction"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textSize="30sp" />
</LinearLayout>

Then I defined some attributes in attrs.xml

 <?xml version="1.0" encoding="utf-8"?>
    <resources>
    <declare-styleable name="CustomEmptyListView">
        <attr name="visualIcon" format="string"/>
        <attr name="message" format="string"/>
        <attr name="textColor" format="color"/>
        <attr name="iconColor" format="color"/>
        <attr name="buttonColor" format="color"/>
        <attr name="buttonVisibility" format="boolean" />
        <attr name="buttonText" format="string" />
    </declare-styleable>
    </resources>

Here is the code for my custom class

public class CustomEmptyListView extends LinearLayout {
    private TextView txtIcon;
    private TextView txtMessage;
    private Button btnAction;

    public CustomEmptyListView(Context context, AttributeSet attrs) {
        super(context, attrs);


    }

    public CustomEmptyListView(Context context) {
        super(context);
        LayoutInflater.from(context).inflate(R.layout.empty_listview, this);
    }

    public CustomEmptyListView(Context context, AttributeSet attrs, int defStyleAttr) {
        this(context, attrs);
        initViews(context, attrs);
    }


    private void initViews(Context context, AttributeSet attrs) {
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CustomEmptyListView, 0, 0);
        String iconText = a.getString(R.styleable.CustomEmptyListView_visualIcon);
        String message = a.getString(R.styleable.CustomEmptyListView_message);
        int buttonColor = a.getColor(R.styleable.CustomEmptyListView_buttonColor, ContextCompat.getColor(context,R.color.blueGreen));
        int textColor = a.getColor(R.styleable.CustomEmptyListView_textColor, ContextCompat.getColor(context,R.color.textCard));
        int iconColor = a.getColor(R.styleable.CustomEmptyListView_textColor, ContextCompat.getColor(context,R.color.light_grey));
        boolean btnVisible = a.getBoolean(R.styleable.CustomEmptyListView_buttonVisibility,true);
        String buttonText = a.getString(R.styleable.CustomEmptyListView_buttonText);
        a.recycle();

        LayoutInflater.from(getContext()).inflate(
                R.layout.empty_listview, this);

        txtIcon = (TextView)findViewById(R.id.textViewIcon);
        txtIcon.setText(iconText);
        txtIcon.setTextColor(iconColor);

        txtMessage = (TextView)findViewById(R.id.textViewMessage);
        txtMessage.setText(message);
        txtMessage.setTextColor(textColor);

        btnAction = (Button)findViewById(R.id.btnAction);
        btnAction.setText(buttonText);
        btnAction.setBackgroundColor(buttonColor);
        btnAction.setTextColor(ContextCompat.getColor(context,R.color.white));
        if(btnVisible){
            btnAction.setVisibility(View.GONE);
        }else{
            btnAction.setVisibility(View.VISIBLE);
        }
    }
}

And after adding it to my layout xml file as follows

<com.package.views.CustomEmptyListView
        android:id="@+id/emptyListView"
        android:visibility="visible"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        custom:message="@string/no_hay_tareas_registradas"
        custom:visualIcon="@string/icon_tasks"
        android:layout_centerInParent="true"
        custom:buttonText="@string/anadir_tarea">

    </com.package.views.CustomEmptyListView>

In my xml editor I only can see a 0 width and height component and nothin shows on runtime. What I'm doing wrong? Thank you in advance!

Answer 1

You must define a correct namespace for your attributes. See this post.