Create RemoveNodeActivity in the sample project that shows an updated list of nodes sorted by latency. This whole activity while be used to add and test the functionallity of removing a node from the nodes list when the app that uses graphenej decides so, and then reconnects to the next best node.

sample/src/main/AndroidManifest.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
     package="cy.agorise.labs.sample">
 
     <uses-permission android:name="android.permission.INTERNET" />
@@ -11,7 +12,8 @@
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
-        android:theme="@style/AppTheme">
+        android:theme="@style/AppTheme"
+        tools:ignore="GoogleAppIndexingWarning">
         <activity android:name=".SubscriptionActivity" />
         <activity android:name=".CallsActivity">
             <intent-filter>
@@ -19,7 +21,8 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
-        <activity android:name=".PerformCallActivity"></activity>
+        <activity android:name=".PerformCallActivity" />
+        <activity android:name=".RemoveNodeActivity" />
     </application>
 
 </manifest>

sample/src/main/java/cy/agorise/labs/sample/CallsActivity.java

@@ -17,6 +17,8 @@ import cy.agorise.graphenej.RPC;
 
 public class CallsActivity extends AppCompatActivity {
 
+    private static final String REMOVE_CURRENT_NODE = "remove_current_node";
+
     @BindView(R.id.call_list)
     RecyclerView mRecyclerView;
 
@@ -50,7 +52,8 @@ public class CallsActivity extends AppCompatActivity {
             RPC.CALL_SET_SUBSCRIBE_CALLBACK,
             RPC.CALL_GET_DYNAMIC_GLOBAL_PROPERTIES,
             RPC.CALL_GET_KEY_REFERENCES,
-            RPC.CALL_GET_ACCOUNT_BALANCES
+            RPC.CALL_GET_ACCOUNT_BALANCES,
+            REMOVE_CURRENT_NODE
         };
 
         @NonNull
@@ -71,6 +74,8 @@ public class CallsActivity extends AppCompatActivity {
                 Intent intent;
                 if(selectedCall.equals(RPC.CALL_SET_SUBSCRIBE_CALLBACK)){
                     intent = new Intent(CallsActivity.this, SubscriptionActivity.class);
+                } else if (selectedCall.equals(REMOVE_CURRENT_NODE)){
+                    intent = new Intent(CallsActivity.this, RemoveNodeActivity.class);
                 }else{
                     intent = new Intent(CallsActivity.this, PerformCallActivity.class);
                     intent.putExtra(Constants.KEY_SELECTED_CALL, selectedCall);

sample/src/main/java/cy/agorise/labs/sample/RemoveNodeActivity.java

@@ -0,0 +1,274 @@
+package cy.agorise.labs.sample;
+
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.ServiceConnection;
+import android.graphics.Color;
+import android.graphics.Typeface;
+import android.os.Build;
+import android.os.Bundle;
+import android.os.IBinder;
+import android.support.annotation.NonNull;
+import android.support.v4.content.ContextCompat;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.util.SortedList;
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.text.SpannableStringBuilder;
+import android.text.Spanned;
+import android.text.style.ForegroundColorSpan;
+import android.text.style.StyleSpan;
+import android.util.Log;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+import java.util.Comparator;
+import java.util.List;
+import java.util.Locale;
+
+import butterknife.BindView;
+import butterknife.ButterKnife;
+import cy.agorise.graphenej.api.android.NetworkService;
+import cy.agorise.graphenej.network.FullNode;
+import io.reactivex.Observer;
+import io.reactivex.android.schedulers.AndroidSchedulers;
+import io.reactivex.disposables.Disposable;
+import io.reactivex.subjects.PublishSubject;
+
+public class RemoveNodeActivity extends AppCompatActivity implements ServiceConnection {
+
+    private final String TAG = this.getClass().getName();
+
+    @BindView(R.id.rvNodes)
+    RecyclerView rvNodes;
+
+    FullNodesAdapter nodesAdapter;
+
+    // Comparator used to sort the nodes in ascending order
+    private final Comparator<FullNode> LATENCY_COMPARATOR = (a, b) ->
+            Double.compare(a.getLatencyValue(), b.getLatencyValue());
+
+    /* Network service connection */
+    private NetworkService mNetworkService;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_remove_node);
+
+        ButterKnife.bind(this);
+
+        rvNodes.setLayoutManager(new LinearLayoutManager(this));
+        nodesAdapter = new FullNodesAdapter(this, LATENCY_COMPARATOR);
+        rvNodes.setAdapter(nodesAdapter);
+    }
+
+    @Override
+    public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
+        // We've bound to LocalService, cast the IBinder and get LocalService instance
+        NetworkService.LocalBinder binder = (NetworkService.LocalBinder) iBinder;
+        mNetworkService = binder.getService();
+
+        if(mNetworkService != null){
+            // PublishSubject used to announce full node latencies updates
+            PublishSubject<FullNode> fullNodePublishSubject = mNetworkService.getNodeLatencyObservable();
+            if(fullNodePublishSubject != null)
+                fullNodePublishSubject.observeOn(AndroidSchedulers.mainThread()).subscribe(nodeLatencyObserver);
+
+            List<FullNode> fullNodes = mNetworkService.getNodes();
+            nodesAdapter.add(fullNodes);
+        }
+    }
+
+    @Override
+    public void onServiceDisconnected(ComponentName componentName) {
+
+    }
+
+    /**
+     * Observer used to be notified about node latency measurement updates.
+     */
+    private Observer<FullNode> nodeLatencyObserver = new Observer<FullNode>() {
+        @Override
+        public void onSubscribe(Disposable d) { }
+
+        @Override
+        public void onNext(FullNode fullNode) {
+            nodesAdapter.add(fullNode);
+        }
+
+        @Override
+        public void onError(Throwable e) {
+            Log.e(TAG,"nodeLatencyObserver.onError.Msg: "+e.getMessage());
+        }
+
+        @Override
+        public void onComplete() { }
+    };
+
+    @Override
+    protected void onStart() {
+        super.onStart();
+        // Bind to LocalService
+        Intent intent = new Intent(this, NetworkService.class);
+        bindService(intent, this, Context.BIND_AUTO_CREATE);
+    }
+
+    @Override
+    protected void onPause() {
+        super.onPause();
+        unbindService(this);
+    }
+
+    class FullNodesAdapter extends RecyclerView.Adapter<FullNodesAdapter.ViewHolder> {
+
+        class ViewHolder extends RecyclerView.ViewHolder {
+            ImageView   ivNodeStatus;
+            TextView    tvNodeName;
+
+            ViewHolder(View itemView) {
+                super(itemView);
+
+                ivNodeStatus    = itemView.findViewById(R.id.ivNodeStatus);
+                tvNodeName      = itemView.findViewById(R.id.tvNodeName);
+            }
+        }
+
+        private final SortedList<FullNode> mSortedList = new SortedList<>(FullNode.class, new SortedList.Callback<FullNode>() {
+            @Override
+            public void onInserted(int position, int count) {
+                notifyItemRangeInserted(position, count);
+            }
+
+            @Override
+            public void onRemoved(int position, int count) {
+                notifyItemRangeRemoved(position, count);
+            }
+
+            @Override
+            public void onMoved(int fromPosition, int toPosition) {
+                notifyItemMoved(fromPosition, toPosition);
+            }
+
+            @Override
+            public void onChanged(int position, int count) {
+                notifyItemRangeChanged(position, count);
+            }
+
+            @Override
+            public int compare(FullNode a, FullNode b) {
+                return mComparator.compare(a, b);
+            }
+
+            @Override
+            public boolean areContentsTheSame(FullNode oldItem, FullNode newItem) {
+                return oldItem.getLatencyValue() == newItem.getLatencyValue();
+            }
+
+            @Override
+            public boolean areItemsTheSame(FullNode item1, FullNode item2) {
+                return item1.getUrl().equals(item2.getUrl());
+            }
+        });
+
+        private final Comparator<FullNode> mComparator;
+
+        private Context mContext;
+
+        FullNodesAdapter(Context context, Comparator<FullNode> comparator) {
+            mContext = context;
+            mComparator = comparator;
+        }
+
+        private Context getContext() {
+            return mContext;
+        }
+
+        @NonNull
+        @Override
+        public FullNodesAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+            Context context = parent.getContext();
+            LayoutInflater inflater = LayoutInflater.from(context);
+
+            View transactionView = inflater.inflate(R.layout.item_node, parent, false);
+
+            return new ViewHolder(transactionView);
+        }
+
+        @Override
+        public void onBindViewHolder(@NonNull ViewHolder viewHolder, int position) {
+            final FullNode fullNode = mSortedList.get(position);
+
+            // Show the green check mark before the node name if that node is the one being used
+            if (fullNode.isConnected())
+                viewHolder.ivNodeStatus.setImageResource(R.drawable.ic_connected);
+            else
+                viewHolder.ivNodeStatus.setImageDrawable(null);
+
+            double latency = fullNode.getLatencyValue();
+
+            // Select correct color span according to the latency value
+            ForegroundColorSpan colorSpan;
+
+            if (latency < 400)
+                colorSpan = new ForegroundColorSpan(ContextCompat.getColor(getContext(), R.color.colorPrimary));
+            else if (latency < 800)
+                colorSpan = new ForegroundColorSpan(Color.rgb(255,136,0)); // Holo orange
+            else
+                colorSpan = new ForegroundColorSpan(Color.rgb(204,0,0)); // Holo red
+
+            // Create a string with the latency number colored according to their amount
+            SpannableStringBuilder ssb = new SpannableStringBuilder();
+
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+                ssb.append(fullNode.getUrl().replace("wss://", ""), new StyleSpan(Typeface.BOLD), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+            }
+            ssb.append(" (");
+
+            // 2000 ms is the timeout of the websocket used to calculate the latency, therefore if the
+            // received latency is greater than such value we can assume the node was not reachable.
+            String ms = latency < 2000 ? String.format(Locale.US, "%.0f ms", latency) : "??";
+
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+                ssb.append(ms, colorSpan, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+            }
+            ssb.append(")");
+
+            viewHolder.tvNodeName.setText(ssb);
+        }
+
+        /**
+         * Functions that adds/updates a FullNode to the SortedList
+         */
+        public void add(FullNode fullNode) {
+            // Remove the old instance of the FullNode before adding a new one. My understanding is that
+            // the sorted list should be able to automatically find repeated elements and update them
+            // instead of adding duplicates but it wasn't working so I opted for manually removing old
+            // instances of FullNodes before adding the updated ones.
+            int removed = 0;
+            for (int i=0;  i<mSortedList.size(); i++)
+            if (mSortedList.get(i - removed).getUrl().equals(fullNode.getUrl()))
+                mSortedList.removeItemAt(i-removed++);
+
+            mSortedList.add(fullNode);
+        }
+
+        /**
+         * Function that adds a whole list of nodes to the SortedList. It should only be used at the
+         * moment of populating the SortedList for the first time.
+         */
+        public void add(List<FullNode> fullNodes) {
+            mSortedList.addAll(fullNodes);
+        }
+
+
+        @Override
+        public int getItemCount() {
+            return mSortedList.size();
+        }
+    }
+}

sample/src/main/res/drawable/ic_connected.xml

@@ -0,0 +1,5 @@
+<vector android:height="24dp" android:tint="#32C832"
+    android:viewportHeight="24.0" android:viewportWidth="24.0"
+    android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#FF000000" android:pathData="M19,3L5,3c-1.11,0 -2,0.9 -2,2v14c0,1.1 0.89,2 2,2h14c1.11,0 2,-0.9 2,-2L21,5c0,-1.1 -0.89,-2 -2,-2zM10,17l-5,-5 1.41,-1.41L10,14.17l7.59,-7.59L19,8l-9,9z"/>
+</vector>

sample/src/main/res/layout/activity_remove_node.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <android.support.v7.widget.RecyclerView
+        android:id="@+id/rvNodes"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toTopOf="@+id/btnRemoveCurrentNode"
+        tools:listitem="@layout/item_node"/>
+
+    <Button
+        android:id="@+id/btnRemoveCurrentNode"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Remove current node"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"/>
+
+</android.support.constraint.ConstraintLayout>

sample/src/main/res/layout/item_node.xml

@@ -0,0 +1,30 @@
+<?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"
+    android:paddingStart="24dp"
+    android:paddingEnd="24dp"
+    android:paddingTop="2dp"
+    android:paddingBottom="2dp">
+
+    <ImageView
+        android:id="@+id/ivNodeStatus"
+        android:layout_width="16dp"
+        android:layout_height="16dp"
+        tools:src="@drawable/ic_connected"/>
+
+    <TextView
+        android:id="@+id/tvNodeName"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="2dp"
+        android:layout_marginLeft="2dp"
+        tools:text="de.palmpayisthebestappinthefreakingworld.io/ws (123ms)"
+        android:ellipsize="middle"
+        android:singleLine="true"
+        android:textColor="#222"
+        android:textSize="16sp"/>
+
+</LinearLayout>