add icon for notebook list’s item

app/src/main/java/org/houxg/leamonax/adapter/NotebookAdapter.java

@@ -1,10 +1,12 @@
 package org.houxg.leamonax.adapter;
 
 
+import android.support.annotation.Nullable;
 import android.support.v7.widget.RecyclerView;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
+import android.widget.ImageView;
 import android.widget.TextView;
 
 import org.houxg.leamonax.R;
@@ -91,7 +93,7 @@ public class NotebookAdapter extends RecyclerView.Adapter<NotebookAdapter.Notebo
 //        boolean hasChild = hasChild(notebookId);
         holder.placeholder.setVisibility(isSuperOrRoot ? View.GONE : View.VISIBLE);
 //        holder.navigator.setVisibility(hasChild ? View.VISIBLE : View.INVISIBLE);
-        holder.navigator.setText(isSuper ? "-" : "+");
+        holder.navigator.setImageResource(isSuper ? R.drawable.ic_expanding : R.drawable.ic_expandable);
         holder.navigator.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
@@ -175,9 +177,10 @@ public class NotebookAdapter extends RecyclerView.Adapter<NotebookAdapter.Notebo
     static class NotebookHolder extends RecyclerView.ViewHolder {
         View itemView;
         @BindView(R.id.navigator)
-        TextView navigator;
+        ImageView navigator;
         @BindView(R.id.tv_title)
         TextView titleTv;
+        @Nullable
         @BindView(R.id.placeholder)
         View placeholder;
 

app/src/main/res/layout/item_add_notebook.xml

@@ -2,34 +2,30 @@
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
+    android:layout_gravity="center_vertical"
+    android:background="?android:attr/selectableItemBackground"
     android:orientation="horizontal">
 
-    <View
-        android:id="@+id/placeholder"
-        android:layout_width="12dp"
-        android:layout_height="wrap_content" />
-
-    <TextView
+    <ImageView
         android:id="@+id/navigator"
         android:layout_width="36dp"
         android:layout_height="match_parent"
-        android:layout_gravity="center_vertical"
-        android:gravity="center"
-        android:text="+"
-        android:textColor="#333"
-        android:textSize="18sp" />
+        android:layout_gravity="start|center_vertical"
+        android:paddingEnd="16dp"
+        android:paddingStart="16dp"
+        android:scaleType="center"
+        android:src="@drawable/ic_add_note_book" />
 
     <TextView
         android:id="@+id/tv_title"
-        android:layout_width="match_parent"
+        android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_gravity="center_vertical"
-        android:gravity="center_vertical|start"
+        android:fontFamily="sans-serif-medium"
         android:paddingBottom="8dp"
-        android:paddingEnd="8dp"
+        android:gravity="center_vertical"
         android:paddingTop="8dp"
         android:text="@string/add_notebook"
         android:textColor="@color/primary_text_light"
-        android:textSize="16sp" />
+        android:textSize="14sp" />
 
 </LinearLayout>

app/src/main/res/layout/item_notebook.xml

@@ -1,37 +1,39 @@
 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    xmlns:tools="http://schemas.android.com/tools"
+    android:clickable="true"
     android:orientation="horizontal">
 
     <View
         android:id="@+id/placeholder"
-        android:layout_width="12dp"
+        android:layout_width="16dp"
         android:layout_height="wrap_content" />
 
-    <TextView
+    <ImageView
         android:id="@+id/navigator"
         android:layout_width="36dp"
         android:layout_height="match_parent"
-        android:layout_gravity="center_vertical"
-        android:gravity="center"
-        android:text="+"
-        android:textColor="#333"
-        android:textSize="18sp" />
+        android:layout_gravity="start|center_vertical"
+        android:background="?android:attr/selectableItemBackground"
+        android:paddingEnd="16dp"
+        android:paddingStart="16dp"
+        android:scaleType="center"
+        android:src="@drawable/ic_expandable" />
 
     <TextView
         android:id="@+id/tv_title"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:layout_gravity="center_vertical"
+        android:layout_gravity="start|center_vertical"
         android:background="?android:attr/selectableItemBackground"
-        android:gravity="center_vertical|start"
+        android:fontFamily="sans-serif-medium"
+        android:gravity="start|center_vertical"
         android:paddingBottom="8dp"
-        android:paddingEnd="8dp"
         android:paddingTop="8dp"
-        tools:text="NotebookTitle"
         android:textColor="@color/primary_text_light"
-        android:textSize="16sp" />
+        android:textSize="14sp"
+        tools:text="NotebookTitle" />
 
 </LinearLayout>