java - 我可以在自身内部存储 Activity 或 Fragment 的静态实例吗？

Question

我需要更新基于 BroadcastReceiver 的 UI 元素。 self 引用存储自己创建的最后一个实例以发送更新有什么问题吗？

public class ExampleFragment extends Fragment {

    private static ExampleFragment sExampleFragment = null; 
    private BroadcastReceiver mNetworkReceiver;    
    private TextView networkStateTextView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        sExampleFragment = this;
        mNetworkReceiver = new NetworkChangeReceiver();
        registerNetworkBroadcast();        
    }

    public void updateTextView(Boolean value) {
        networkStateTextView.setText(String.valueOf(value));
    }

    public static void setNetworkConnectedState(boolean value){        
        sExampleFragment.updateTextView(value);
    }

    private void registerNetworkBroadcast() {
        getContext().registerReceiver(mNetworkReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
    }

    protected void unregisterNetworkChanges() {
        try {
            getContext().unregisterReceiver(mNetworkReceiver);
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        }
    }
}

我的广播接收器:

public class NetworkChangeReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(final Context context, final Intent intent) {
        try
        {
            Log.d("Network Available ", String.valueOf(isOnline(context)));
            ExampleFragment.setNetworkConnectedState(isOnline(context));
        } catch (NullPointerException e) {
            e.printStackTrace();
        }
    }

    private boolean isOnline(Context context) {
        try {
            ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo netInfo = cm.getActiveNetworkInfo();
            //should check null because in airplane mode it will be null
            return (netInfo != null && netInfo.isConnected());
        } catch (NullPointerException e) {
            e.printStackTrace();
            return false;
        }
    }
}

有没有办法在不让静态成员污染我的 Fragment 的情况下做到这一点？

Answer 1

        // Monitor network changed events
        mNetworkReceiver = new NetworkChangeReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {

                try
                {
                    Log.d("Network Available ", String.valueOf(isOnline(context)));
                    ///networkChanged(isOnline(context));

                    if(isOnline(context)){
                        connectedImageView.setBackground(ContextCompat.getDrawable(getContext(), R.drawable.ic_connected_yes));
                        connectedTextView.setText(R.string.connected_yes);
                    }else{
                        connectedImageView.setBackground(ContextCompat.getDrawable(getContext(), R.drawable.ic_connected_no));
                        connectedTextView.setText(R.string.connected_no);
                    }

                } catch (NullPointerException e) {
                    e.printStackTrace();
                }
            }
        };