通过包名查看应用Activity是否存在

public boolean checkBrowser(String packageName) {
if (packageName == null || "".equals(packageName))
return false;
try {
ApplicationInfo info = getPackageManager().getApplicationInfo(
packageName, PackageManager.GET_UNINSTALLED_PACKAGES);
return true;
} catch (NameNotFoundException e) {
return false;
}
}

Intent intent = new Intent();
intent.setClassName("包名", "类名");
if(getPackageManager().resolveActivity(intent, 0) == null) {
//说明系统中不存在这个activity
}

//电子市场包名com.android.vending