判断设备是否已经安装某应用

//主要是判断某个包是否已存在

 public static boolean isLinePgAInstalled(Context cxt) {
  try {
   PackageInfo info = cxt.getPackageManager().getPackageInfo(PACKE_NAME, 0);
   if (info != null) {
    return true;
   }
  } catch (NameNotFoundException e) {
   e.printStackTrace();
  }
  return false;
 }