Print the contents of a Bundle to Logcat?

Bundle#keySet() should work.

for (String key: bundle.keySet())
{
  Log.d ("myApplication", key + " is a key in the bundle");
}

And if you want to get the Object, you can use Bundle#get(String key)(which is also in the same documentation I linked at the top of my answer). However, keep in mind using the generic get() call:

• You're working with Object. If you're simply printing to a Log, toString() will be invoked and all will be fine. However, if you actually want to use the key's pair, you need to do instanceof checks to avoid calling the wrong method.
• Since toString will be invoked, if you have a special Object (eg ArrayLists, or special Serializable/Parcelable extras) you're most likely not going to get anything useful from the printout.

You can get more specific by printing the mapped value as follows:

for (String key : bundle.keySet())
{
    Log.d("Bundle Debug", key + " = \"" + bundle.get(key) + "\"");
}