android 检查手机是否安装该程序

public boolean checkPrograme(String packName,String actvityName) {
       boolean flag = false;
       PackageManager manager = getPackageManager();
       // 只查找启动方式为LAUNCHER并且是ACTION_MAIN的APP
       Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
       mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
      // 根据Intent值查询这样的app
      final List<ResolveInfo> apps = manager.queryIntentActivities(mainIntent, 0);
   
      for(ResolveInfo app:apps){
        //该应用的包名和主Activity  
        String pkg = app.activityInfo.packageName;  
        String cls = app.activityInfo.name; 
        if(pkg.equals(packName) || cls.equals(actvityName)){
                   try {
              info = manager.getPackageInfo(pkg, 0);
           } catch (NameNotFoundException e) {
              e.printStackTrace();
           }
           String mVersonName = info.versionName;
           int versionCode = info.versionCode;
           Log.v("TAG", "==========mVersonName  :"+mVersonName);
           break;
      }
      Log.v("TAG", "pkg  :"+pkg);
      Log.v("TAG", "cls  :"+cls);
    }
    return flag;
  }