Android 無網路彈出對話框

 if (isConnect(this) == false) {
Toast.makeText(MainActivity.this, "設備無連接，請鏈接到網絡", 2000).show();
}
else {
Toast.makeText(MainActivity.this, "鏈接到球賽比分網絡", 1000).show();

}

private boolean isConnect(
MainActivity mainActivity) {
ConnectivityManager conManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo networkInfo = conManager
.getActiveNetworkInfo();

if (networkInfo != null) { // 注意，這個判斷一定要的哦，要不然會出錯

return networkInfo
.isAvailable();

}

return false;