Starting with a clean project created with: android create project -n something -t android-7 -p something -k com.example.something -a Something When I run ant debug install and open the application in my emulator, I see (as expected) Here's where it goes bad. I now change something trivial in the application. In this example, I'm going to remove the setContentView call from the main activity so it looks like this: package com.example.something; import android.app.Activity; import android.os.Bundle; public class Something extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //setContentView(R.layout.main); REMOVED } } Now I rebuild the application with ant debug install and run it in the emulator. I see this: This is wrong. I just removed the text with my previous edit. If I do ant clean before ant debug install , I get the expected result: I don't want to have