higekick

ApplicationInfo appInfo = getPackageManager().getApplicationInfo(getPackageName(), 0);
long lastInstallTime = new File(appInfo.sourceDir).lastModified();
Log.d("INSTALL_TIME".TAG, "install time = " + Long.toString(lastInstallTime)); //1.

PackageInfo pkgInfo = getPackageManager().getPackageInfo(getPackageName(), PackageManager.GET_META_DATA);
Log.d("INSTALL_TIME", "firstInstallTime = " + Long.toString(pkgInfo.firstInstallTime)); //2.
Log.d("INSTALL_TIME", "firstInstallTime = " + Long.toString(pkgInfo.lastUpdateTime)); //3.