How to write build time stamp into apk

Question

1. Making some changes in Android Contacts package
2. Using mm (make) command to build this application

Because I have to change and

Answer 1

Edit: My answer does not work anymore since option keepTimestampsInApk was removed. Working in 2020 is https://stackoverflow.com/a/26372474/6937282 (also https://stackoverflow.com/a/22649533/6937282 for more details)

Original answer:

A hint for solution "last modification time of classes.dex file" an newer AndroidStudio versions: In default config the timestamp is not written anymore to files in apk file. Timestamp is always "Nov 30 1979".

You can change this behavior by adding this line to file

%userdir%/.gradle/gradle.properties (create if not existing)

android.keepTimestampsInApk = true

See Issue 220039

(Must be in userdir, gradle.properties in project build dir seems not to work)

Answer 2

If you use Gradle, you can add buildConfigField with timestamp updated at build time.

android {
    defaultConfig {
        buildConfigField "long", "TIMESTAMP", System.currentTimeMillis() + "L"
    }
}

Then read it at runtime.

Date buildDate = new Date(BuildConfig.TIMESTAMP);

Answer 3

Install time : packageInfo.lastUpdateTime
build time   : zf.getEntry("classes.dex").getTime()

Both are differnet time. You can check with the code below.

public class BuildInfoActivity extends Activity {

    private static final String TAG = BuildInfoActivity.class.getSimpleName();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        try {

            PackageManager pm = getPackageManager();
            PackageInfo packageInfo = null;
            try {
                packageInfo = pm.getPackageInfo(getPackageName(), 0);
            } catch (NameNotFoundException e) {
                e.printStackTrace();
            }

            // install datetime
            String appInstallDate = DateUtils.getDate(
                    "yyyy/MM/dd hh:mm:ss.SSS", packageInfo.lastUpdateTime);

            // build datetime
            String appBuildDate = DateUtils.getDate("yyyy/MM/dd hh:mm:ss.SSS",
                    DateUtils.getBuildDate(this));

            Log.i(TAG, "appBuildDate = " + appBuildDate);
            Log.i(TAG, "appInstallDate = " + appInstallDate);

        } catch (Exception e) {
        }

    }

    static class DateUtils {

        public static String getDate(String dateFormat) {
            Calendar calendar = Calendar.getInstance();
            return new SimpleDateFormat(dateFormat, Locale.getDefault())
                    .format(calendar.getTime());
        }

        public static String getDate(String dateFormat, long currenttimemillis) {
            return new SimpleDateFormat(dateFormat, Locale.getDefault())
                    .format(currenttimemillis);
        }

        public static long getBuildDate(Context context) {

            try {
                ApplicationInfo ai = context.getPackageManager()
                        .getApplicationInfo(context.getPackageName(), 0);
                ZipFile zf = new ZipFile(ai.sourceDir);
                ZipEntry ze = zf.getEntry("classes.dex");
                long time = ze.getTime();

                return time;

            } catch (Exception e) {
            }

            return 0l;
        }

    }
}

Answer 4

Method which checks date of last modification of classes.dex, this means last time when your app's code was built:

  try{
     ApplicationInfo ai = getPackageManager().getApplicationInfo(getPackageName(), 0);
     ZipFile zf = new ZipFile(ai.sourceDir);
     ZipEntry ze = zf.getEntry("classes.dex");
     long time = ze.getTime();
     String s = SimpleDateFormat.getInstance().format(new java.util.Date(time));
     zf.close();
  }catch(Exception e){
  }

Tested, and works fine, even if app is installed on SD card.