Android Handler Message and ListView

Question

Here's my error:

*** Uncaught remote exception!  (Exceptions are not yet supported across processes.)
android.util.AndroidRuntimeException: { what=1008 when=368280372 } This message is already in use.
at android.os.MessageQueue.enqueueMessage(MessageQueue.java:171)
at android.os.Handler.sendMessageAtTime(Handler.java:457)
at android.os.Handler.sendMessageDelayed(Handler.java:430)
at android.os.Handler.sendMessage(Handler.java:367)
at android.view.ViewRoot.dispatchAppVisibility(ViewRoot.java:2748)

What I'm attempting is to have a listview, that is populated by custom list items, each list item has multiple views and each view has an onclick listener attached. When this onClickListener is pressed it sends a Message to a Handler with a what and arg1 arguments. Clicking one of my elements fires an intent to start a new activity. Clicking the other shows a toast. When these are pressed in a combination I get the error above. Namely clicking the text to fire the intent, (then press back) then clicking the image to show the toast, then when you click the text to fire the intent again I get the FC.

And here is the code below, I tried to remove as much cruft as I could to get to the bones of the error:

If you want to skip to whats important look at the onClickListener's in ConversationAdapter.class and how they interact with StartPage.class

Android Manifest:

<?xml version="1.0" encoding="utf-8"?>
  <manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.handler.test"
    android:versionCode="1"
    android:versionName="1.0">
      <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".StartPage"
              android:label="@string/app_name">
            <intent-filter>
              <action android:name="android.intent.action.MAIN" />
              <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    <activity
        android:name=".DetailsPage"
        android:label="DetailsPage"
        >
    </activity> 
    </application>
    <uses-sdk android:minSdkVersion="3" />
</manifest>

StartPage.class:

package com.handler.test;

import java.util.ArrayList;

import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.widget.Toast;

public class StartPage extends ListActivity {

private ArrayList<Conversation> mConversations = null;
private ConversationAdapter mAdapter;
private Context mContext;
private ProgressDialog mProgressDialog;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    mContext = this;

    mConversations = new ArrayList<Conversation>();
    this.mAdapter = new ConversationAdapter(mContext, R.layout.inbox_row, mConversations, mHandler);
    setListAdapter(this.mAdapter);

    new Thread(new Runnable() {
        @Override
        public void run() {
            getConversations();
        }
    }).start();

    mProgressDialog = ProgressDialog.show(StartPage.this, "Please wait...", "Retrieving data ...", true);
}

private void getConversations() {
    try {
        mConversations = new ArrayList<Conversation>();
        Conversation o1 = new Conversation();
        o1.setStatus("SF services");
        o1.setMessage("Pending");           
        mConversations.add(o1);
    } catch (Exception e) {
        Log.e("BACKGROUND_PROC", e.getMessage());
    }
    runOnUiThread(returnRes);
}

private Runnable returnRes = new Runnable() {
    @Override
    public void run() {
        if(mConversations != null && mConversations.size() > 0){
            mAdapter.notifyDataSetChanged();
            for(int i=0;i<mConversations.size();i++)
                mAdapter.add(mConversations.get(i));
        }
        mProgressDialog.dismiss();
        mAdapter.notifyDataSetChanged();
    }
  };

private Handler mHandler = new Handler(){
    @Override
    public void handleMessage(Message msg) {
        int convIndex = msg.arg1;
        int viewTouched = msg.what;
        switch(viewTouched){
            case ConversationAdapter.PROF_ICON:
                showNumber(convIndex);
            break;
            case ConversationAdapter.MESSAGE:
                showMessageDetails(convIndex);
            break;
        }
        super.handleMessage(msg);
    }
};

private void showNumber(int convIndex) {
    Toast.makeText(mContext, "Pressed: "+convIndex, Toast.LENGTH_LONG).show();
}

private void showMessageDetails(int convIndex) {
    final Conversation conv = mConversations.get(convIndex);
    Intent i = new Intent(mContext, DetailsPage.class);
    i.putExtra("someExtra", conv);
    startActivity(i);
}
}

DetailsPage.class

package com.handler.test;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class DetailsPage extends Activity {


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    Log.i("Test", "Details Page");      
}


}

Conversation.class:

package com.handler.test;

import java.io.Serializable;

public class Conversation implements Serializable {

private static final long serialVersionUID = -437261671361122258L;

private String status;

public String getStatus() {
    return status;
}
public void setStatus(String status) {
    this.status = status;
}
}

ConversationAdapter.class:

package com.handler.test;

import java.util.ArrayList;

import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;

public class ConversationAdapter extends ArrayAdapter<Conversation> {

public static final int PROF_ICON = 0;
public static final int MESSAGE = 1;

private Context mContext;
private Handler mHandler;
private ArrayList<Conversation> mItems;
private int mXmlId;

private LinearLayout detailsOfConv;
private ImageView iconImage;

public ConversationAdapter(Context context, int textViewResourceId, ArrayList<Conversation> items, Handler handler) {
    super(context, textViewResourceId, items);
    this.mContext = context;
    this.mItems = items;
    this.mXmlId = textViewResourceId;
    this.mHandler = handler;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View v = convertView;
    if (v == null) {
        LayoutInflater vi = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        v = vi.inflate(mXmlId, null);
    }
    final Message m = new Message();
    m.arg1 = position;
    Conversation c = mItems.get(position);
    if (c != null) {
        iconImage = (ImageView) v.findViewById(R.id.icon);
        if (iconImage != null) {
            iconImage.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    m.what = PROF_ICON;
                    mHandler.sendMessage(m);
                }
            });
        }

        detailsOfConv = (LinearLayout) v.findViewById(R.id.details);
        if(detailsOfConv != null){
            detailsOfConv.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    m.what = MESSAGE;
                    mHandler.sendMessage(m);
                }
            });
        }
    }
    return v;
}
}

main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="10dip"
>
<ListView
 android:id="@+id/android:list"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:cacheColorHint="#00000000"
 />
</LinearLayout>

inbox_row.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="?android:attr/listPreferredItemHeight"
  android:padding="6dip">
  <ImageView
    android:id="@+id/icon"
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:layout_marginRight="6dip"
    android:src="@drawable/icon" />
  <LinearLayout
    android:id="@+id/details"
    android:orientation="vertical"
    android:layout_width="0dip"
    android:layout_weight="1"
    android:layout_height="fill_parent">
    <TextView
        android:id="@+id/toptext"
        android:textColor="#99FF66"
        android:layout_width="fill_parent"
        android:layout_height="0dip"
        android:layout_weight="1"
        android:singleLine="true"
        android:text="123456789"
        />       
  </LinearLayout>
</LinearLayout>

Answer 1

My guess would be that you are sending twice the same message. Indeed in the code there is one new Message() and two mHandler.sendMessage(m) which are possibly both executed.

Try making a new message for every time you send a message.

Edited:

Message.obtain() is preferable to Message m = new Message() (because it recycles used messages under the hood)

In your case you could use new.copyFrom(old) if you need a copy of existing message.