我对单击Listener的启动设备热点的按钮有问题。这是错误
原因：java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法“ void android.widget.TextView.setOnClickListener（android.view.View $ OnClickListener）”
请有人帮我解决问题
public static final String TAG = "ShareActivity";
public static final String PREFERENCES_KEY_SHARED_FILE_PATHS = "FileDitto_shared_file_paths";
public static final String PREFERENCES_KEY_DATA_WARNING_SKIP = "FileDitto_data_warning_skip";
private static final int REQUEST_WRITE_SETTINGS = 1;
TextView m_sender_wifi_info;
TextView m_noReceiversText;
RelativeLayout m_receivers_list_layout;
RecyclerView m_receiversList;
SwitchCompat m_apControlSwitch;
TextView m_showShareList;
Toolbar m_toolbar;
private ReceiversListingAdapter m_receiversListAdapter;
private CompoundButton.OnCheckedChangeListener m_sender_ap_switch_listener;
private ShareUIHandler m_uiUpdateHandler;
private BroadcastReceiver m_p2pServerUpdatesListener;
private HotspotControl hotspotControl;
private boolean isApEnabled = false;
private boolean shouldAutoConnect = true;
private String[] m_sharedFilePaths = null;
private static final int PERMISSIONS_REQUEST_CODE_ACCESS_COARSE_LOCATION = 100;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
m_sender_wifi_info = (TextView) findViewById(R.id.p2p_sender_wifi_hint);
m_noReceiversText = (TextView) findViewById(R.id.p2p_no_receivers_text);
m_showShareList = (TextView) findViewById(R.id.p2p_sender_items_label);
m_showShareList.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
showSharedFilesDialog();
}
});
m_receivers_list_layout = (RelativeLayout) findViewById(R.id.p2p_receivers_list_layout);
m_receiversList = (RecyclerView) findViewById(R.id.p2p_receivers_list);
m_apControlSwitch = (SwitchCompat) findViewById(R.id.p2p_sender_ap_switch);
m_toolbar = (Toolbar) findViewById(R.id.toolbar);
m_toolbar.setTitle(getString(R.string.send_title));
setSupportActionBar(m_toolbar);
getSupportActionBar().setDisplayShowTitleEnabled(true);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
hotspotControl = HotspotControl.getInstance(getApplicationContext());
m_receiversList.setLayoutManager(new LinearLayoutManager(getApplicationContext()));
m_receiversList.addItemDecoration(new ItemFix(getResources().getDrawable(R.drawable.li_divider)));
if (null != getIntent() && getIntent().hasExtra(DittoService.EXTRA_FILE_PATHS))
m_sharedFilePaths = getIntent().getStringArrayExtra(DittoService.EXTRA_FILE_PATHS);
SharedPreferences prefs = getSharedPreferences(getPackageName(), Context.MODE_PRIVATE);
if (null == m_sharedFilePaths)
m_sharedFilePaths = Utils.toStringArray(prefs.getString(PREFERENCES_KEY_SHARED_FILE_PATHS, null));
else
prefs.edit().putString(PREFERENCES_KEY_SHARED_FILE_PATHS, new JSONArray(Arrays.asList(m_sharedFilePaths)).toString()).apply();
m_receiversListAdapter = new ReceiversListingAdapter(new ArrayList<HotspotControl.WifiScanResult>(), m_sharedFilePaths);
m_receiversList.setAdapter(m_receiversListAdapter);
m_sender_ap_switch_listener = new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (isChecked) {
if (!isOreoOrAbove()) {
if (Build.VERSION.SDK_INT >= 23 &&
Utils.getTargetSDKVersion(getApplicationContext()) >= 23 && !Settings.System.canWrite(DittoActivity.this)) {
changeApControlCheckedStatus(false);
showMessageDialogWithListner(getString(R.string.p2p_sender_system_settings_permission_prompt), new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Intent intent = new Intent(Settings.ACTION_MANAGE_WRITE_SETTINGS);
intent.setData(Uri.parse("package:" + getPackageName()));
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivityForResult(intent, REQUEST_WRITE_SETTINGS);
}
}, false, true);
return;
} else if (!getSharedPreferences(getPackageName(), Context.MODE_PRIVATE).getBoolean(PREFERENCES_KEY_DATA_WARNING_SKIP, false) && Utils.isMobileDataEnabled(getApplicationContext())) {
changeApControlCheckedStatus(false);
showDataWarningDialog();
return;
}
} else if (!checkLocationPermission()) {
changeApControlCheckedStatus(false);
return;
}
enableAp();
} else {
changeApControlCheckedStatus(true);
showMessageDialogWithListner(getString(R.string.p2p_sender_close_warning), new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Log.d(TAG, "sending intent to service to stop p2p..");
resetSenderUi(true);
}
}, true, false);
}
}
};
m_apControlSwitch.setOnCheckedChangeListener(m_sender_ap_switch_listener);
m_p2pServerUpdatesListener = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
if (isFinishing() || null == intent)
return;
int intentType = intent.getIntExtra(DittoService.ShareIntents.TYPE, 0);
if (intentType == DittoService.ShareIntents.Types.FILE_TRANSFER_STATUS) {
String fileName = intent.getStringExtra(DittoService.ShareIntents.SHARE_SERVER_UPDATE_FILE_NAME);
updateReceiverListItem(intent.getStringExtra(DittoService.ShareIntents.SHARE_CLIENT_IP), intent.getIntExtra(DittoService.ShareIntents.SHARE_TRANSFER_PROGRESS, -1), intent.getStringExtra(DittoService.ShareIntents.SHARE_SERVER_UPDATE_TEXT), fileName);
} else if (intentType == DittoService.ShareIntents.Types.AP_DISABLED_ACKNOWLEDGEMENT) {
shouldAutoConnect = false;
resetSenderUi(false);
}
}
};
registerReceiver(m_p2pServerUpdatesListener, new IntentFilter(DittoService.ShareIntents.SHARE_SERVER_UPDATES_INTENT_ACTION));
}
@Override
protected void onResume() {
super.onResume();
if (Utils.isShareServiceRunning(getApplicationContext())) {
if (!m_apControlSwitch.isChecked()) {
Log.e(TAG, "p2p service running, changing switch status and start handler for ui changes");
changeApControlCheckedStatus(true);
}
refreshApData();
m_receivers_list_layout.setVisibility(View.VISIBLE);
} else if (m_apControlSwitch.isChecked()) {
changeApControlCheckedStatus(false);
resetSenderUi(false);
}
else if (shouldAutoConnect) {
m_apControlSwitch.setChecked(true);
}
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == android.R.id.home) {
onBackPressed();
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
protected void onDestroy() {
super.onDestroy();
if (null != m_p2pServerUpdatesListener)
unregisterReceiver(m_p2pServerUpdatesListener);
if (null != m_uiUpdateHandler)
m_uiUpdateHandler.removeCallbacksAndMessages(null);
m_uiUpdateHandler = null;
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode) {
case PERMISSIONS_REQUEST_CODE_ACCESS_COARSE_LOCATION:
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
enableAp();
} else {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.ACCESS_COARSE_LOCATION)) {
showMessageDialogWithListner(getString(R.string.p2p_receiver_gps_permission_warning), new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
checkLocationPermission();
}
}, true, true);
} else {
showMessageDialogWithListner(getString(R.string.p2p_receiver_gps_no_permission_prompt), new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
try {
Intent intent = new Intent();
intent.setAction(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
Uri uri = Uri.fromParts("package", getPackageName(), null);
intent.setData(uri);
startActivity(intent);
} catch (ActivityNotFoundException anf) {
Toast.makeText(getApplicationContext(), "Settings activity not found", Toast.LENGTH_SHORT).show();
}
}
}, true, true);
}
}
}
}
public void showMessageDialogWithListner(String message,
DialogInterface.OnClickListener listner, boolean showNegavtive,
final boolean finishCurrentActivity) {
if (isFinishing())
return;
final AlertDialog.Builder builder = new AlertDialog.Builder(this, R.style.AppCompatAlertDialogStyle);
builder.setCancelable(false);
builder.setMessage(Html.fromHtml(message));
builder.setPositiveButton(getString(R.string.Action_Ok), listner);
if (showNegavtive)
builder.setNegativeButton(getString(R.string.Action_cancel),
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if (finishCurrentActivity)
finish();
else dialog.dismiss();
}
});
builder.show();
}
@TargetApi(23)
private boolean checkLocationPermission() {
if (Build.VERSION.SDK_INT >= 23 && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(
this,
new String[]{Manifest.permission.ACCESS_COARSE_LOCATION},
PERMISSIONS_REQUEST_CODE_ACCESS_COARSE_LOCATION
);
return false;
}
return true;
}
public void showDataWarningDialog() {
if (isFinishing())
return;
final AlertDialog.Builder builder = new AlertDialog.Builder(this, R.style.AppCompatAlertDialogStyle);
builder.setCancelable(false);
builder.setMessage(getString(R.string.sender_data_on_warning));
builder.setPositiveButton(getString(R.string.label_settings), new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
startActivity(new Intent(
Settings.ACTION_SETTINGS));
}
});
builder.setNegativeButton(getString(R.string.label_thats_ok),
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
changeApControlCheckedStatus(true);
enableAp();
}
});
builder.setNeutralButton(getString(R.string.label_dont_ask), new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
SharedPreferences prefs = getSharedPreferences(getPackageName(), Context.MODE_PRIVATE);
prefs.edit().putBoolean(PREFERENCES_KEY_DATA_WARNING_SKIP, true).apply();
changeApControlCheckedStatus(true);
enableAp();
}
});
builder.show();
}
void showSharedFilesDialog() {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Shared Files");
builder.setItems(m_sharedFilePaths, null);
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
dialogInterface.dismiss();
}
});
builder.show();
}
private void enableAp() {
m_sender_wifi_info.setText(getString(R.string.p2p_sender_hint_connecting));
startP2pSenderWatchService();
refreshApData();
m_receivers_list_layout.setVisibility(View.VISIBLE);
}
private void disableAp() {
//Send STOP action to service
Intent p2pServiceIntent = new Intent(getApplicationContext(), DittoService.class);
p2pServiceIntent.setAction(DittoService.WIFI_AP_ACTION_STOP);
startService(p2pServiceIntent);
isApEnabled = false;
}
private void startP2pSenderWatchService() {
Intent p2pServiceIntent = new Intent(getApplicationContext(), DittoService.class);
p2pServiceIntent.putExtra(DittoService.EXTRA_FILE_PATHS, m_sharedFilePaths);
if (null != getIntent()) {
p2pServiceIntent.putExtra(DittoService.EXTRA_PORT, isOreoOrAbove() ? DEFAULT_PORT_OREO : getIntent().getIntExtra(DittoService.EXTRA_PORT, 0));
p2pServiceIntent.putExtra(DittoService.EXTRA_SENDER_NAME, getIntent().getStringExtra(DittoService.EXTRA_SENDER_NAME));
}
p2pServiceIntent.setAction(DittoService.WIFI_AP_ACTION_START);
startService(p2pServiceIntent);
}
private void startHostspotCheckOnService() {
Intent p2pServiceIntent = new Intent(getApplicationContext(), DittoService.class);
p2pServiceIntent.setAction(DittoService.WIFI_AP_ACTION_START_CHECK);
startService(p2pServiceIntent);
}
private void refreshApData() {
if (null == m_uiUpdateHandler)
m_uiUpdateHandler = new ShareUIHandler(this);
updateApStatus();
listApClients();
}
private void updateApStatus() {
if (!HotspotControl.isSupported()) {
m_sender_wifi_info.setText("Warning: Hotspot mode not supported!\n");
}
if (hotspotControl.isEnabled()) {
if (!isApEnabled) {
isApEnabled = true;
startHostspotCheckOnService();
}
WifiConfiguration config = hotspotControl.getConfiguration();
String ip = Build.VERSION.SDK_INT >= 23 ? WifiUtils.getHostIpAddress() : hotspotControl.getHostIpAddress();
if (TextUtils.isEmpty(ip))
ip = "";
else
ip = ip.replace("/", "");
m_toolbar.setSubtitle(getString(R.string.p2p_sender_subtitle));
m_sender_wifi_info.setText(getString(R.string.p2p_sender_hint_wifi_connected, config.SSID, config.preSharedKey, "http://" + ip + ":" + hotspotControl.getShareServerListeningPort()));
if (m_showShareList.getVisibility() == View.GONE) {
m_showShareList.append(String.valueOf(m_sharedFilePaths.length));
m_showShareList.setVisibility(View.VISIBLE);
}
}
if (null != m_uiUpdateHandler) {
m_uiUpdateHandler.removeMessages(UPDATE_AP_STATUS);
m_uiUpdateHandler.sendEmptyMessageDelayed(UPDATE_AP_STATUS, 1500);
}
}
private synchronized void listApClients() {
if (hotspotControl == null) {
return;
}
hotspotControl.getConnectedWifiClients(2000,
new HotspotControl.WifiClientConnectionListener() {
public void onClientConnectionAlive(final HotspotControl.WifiScanResult wifiScanResult) {
runOnUiThread(new Runnable() {
@Override
public void run() {
addReceiverListItem(wifiScanResult);
}
});
}
@Override
public void onClientConnectionDead(final HotspotControl.WifiScanResult c) {
Log.e(TAG, "onClientConnectionDead: " + c.ip);
runOnUiThread(new Runnable() {
@Override
public void run() {
onReceiverDisconnected(c.ip);
}
});
}
public void onWifiClientsScanComplete() {
runOnUiThread(new Runnable() {
@Override
public void run() {
if (null != m_uiUpdateHandler) {
m_uiUpdateHandler.removeMessages(LIST_API_CLIENTS);
m_uiUpdateHandler.sendEmptyMessageDelayed(LIST_API_CLIENTS, 1000);
}
}
});
}
}
);
}
private void resetSenderUi(boolean disableAP) {
m_uiUpdateHandler.removeCallbacksAndMessages(null);
m_sender_wifi_info.setText(getString(R.string.p2p_sender_hint_text));
m_receivers_list_layout.setVisibility(View.GONE);
m_showShareList.setVisibility(View.GONE);
m_toolbar.setSubtitle("");
if (disableAP)
disableAp();
else {
changeApControlCheckedStatus(false);
}
if (null != m_receiversListAdapter)
m_receiversListAdapter.clear();
m_noReceiversText.setVisibility(View.VISIBLE);
}
private void changeApControlCheckedStatus(boolean checked) {
m_apControlSwitch.setOnCheckedChangeListener(null);
m_apControlSwitch.setChecked(checked);
m_apControlSwitch.setOnCheckedChangeListener(m_sender_ap_switch_listener);
shouldAutoConnect = checked;
}
private void updateReceiverListItem(String ip, int progress, String updatetext, String fileName) {
View taskListItem = m_receiversList.findViewWithTag(ip);
if (null != taskListItem) {
ReceiversListItemHolder holder = new ReceiversListItemHolder(taskListItem);
if (updatetext.contains("Error in file transfer")) {
holder.resetTransferInfo(fileName);
return; }
holder.update(fileName, updatetext, progress);
} else {
Log.e(TAG, "no list item found with this IP******");
} }
private void addReceiverListItem(HotspotControl.WifiScanResult wifiScanResult) {
List<HotspotControl.WifiScanResult> wifiScanResults = m_receiversListAdapter.getObjects();
if (null != wifiScanResults && wifiScanResults.indexOf(wifiScanResult) != -1) {
Log.e(TAG, "duplicate client, try updating connection status");
View taskListItem = m_receiversList.findViewWithTag(wifiScanResult.ip);
if (null == taskListItem)
return;
ReceiversListItemHolder holder = new ReceiversListItemHolder(taskListItem);
if (holder.isDisconnected()) {
Log.d(TAG, "changing disconnected ui to connected: " + wifiScanResult.ip);
holder.setConnectedUi(wifiScanResult);
}
} else {
m_receiversListAdapter.add(wifiScanResult);
if (m_noReceiversText.getVisibility() == View.VISIBLE)
m_noReceiversText.setVisibility(View.GONE);
} }
private void onReceiverDisconnected(String ip) {
View taskListItem = m_receiversList.findViewWithTag(ip);
if (null != taskListItem) {
ReceiversListItemHolder holder = new ReceiversListItemHolder(taskListItem);
if (!holder.isDisconnected())
holder.setDisconnectedUi();
// m_receiversListAdapter.remove(new WifiApControl.Client(ip, null, null));
}
if (m_receiversListAdapter.getItemCount() == 0)
m_noReceiversText.setVisibility(View.VISIBLE);
}
static class ReceiversListItemHolder extends RecyclerView.ViewHolder {
TextView title, connection_status;
ReceiversListItemHolder(View itemView) {
super(itemView);
title = (TextView) itemView.findViewById(R.id.p2p_receiver_title);
connection_status = (TextView) itemView.findViewById(R.id.p2p_receiver_connection_status);
}
void setConnectedUi(HotspotControl.WifiScanResult wifiScanResult) {
title.setText(wifiScanResult.ip);
connection_status.setText("Connected");
connection_status.setTextColor(Color.GREEN);
}
void resetTransferInfo(String fileName) {
View v = itemView.findViewWithTag(fileName);
if (null == v) {
Log.e(TAG, "resetTransferInfo - no view found with file name tag!!");
return;
}
((TextView) v).setText("");
}
void update(String fileName, String transferData, int progress) {
View v = itemView.findViewWithTag(fileName);
if (null == v) {
Log.e(TAG, "update - no view found with file name tag!!");
return;
}
if (v.getVisibility() == View.GONE)
v.setVisibility(View.VISIBLE);
((TextView) v).setText(transferData);
}
void setDisconnectedUi() {
connection_status.setText("Disconnected");
connection_status.setTextColor(Color.RED);
}
boolean isDisconnected() {
return "Disconnected".equalsIgnoreCase(connection_status.getText().toString());
}
}
private static class ReceiversListingAdapter extends RecyclerViewArrayAdapter<HotspotControl.WifiScanResult, ReceiversListItemHolder> {
String[] sharedFiles;
ReceiversListingAdapter(List<HotspotControl.WifiScanResult> objects, String[] sharedFiles) {
super(objects);
this.sharedFiles = sharedFiles;
}
@Override
public ReceiversListItemHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LinearLayout itemView = (LinearLayout) LayoutInflater.from(parent.getContext()).
inflate(R.layout.receivers, parent, false);
//Add at least those many textviews of shared files list size so that if a receiver decides to download them all at once, list item can manage to show status of all file downloads
if (null != sharedFiles && sharedFiles.length > 0)
for (int i = 0; i < sharedFiles.length; i++) {
TextView statusView = (TextView) LayoutInflater.from(parent.getContext()).
inflate(R.layout.include_sender_list_item, parent, false);
statusView.setTag(sharedFiles[i].substring(sharedFiles[i].lastIndexOf('/') + 1, sharedFiles[i].length()));
statusView.setVisibility(View.GONE);
statusView.setTextColor(getRandomColor());
itemView.addView(statusView);
}
return new ReceiversListItemHolder(itemView);
}
@Override
public void onBindViewHolder(ReceiversListItemHolder holder, int position) {
HotspotControl.WifiScanResult receiver = mObjects.get(position);
if (null == receiver)
return;
holder.itemView.setTag(receiver.ip);
holder.setConnectedUi(receiver);
}}
static class ShareUIHandler extends Handler {
WeakReference<DittoActivity> mActivity;
static final int LIST_API_CLIENTS = 100;
static final int UPDATE_AP_STATUS = 101;
ShareUIHandler(DittoActivity activity) {
mActivity = new WeakReference<>(activity);
}
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
DittoActivity activity = mActivity.get();
if (null == activity || msg == null || !activity.m_apControlSwitch.isChecked())
return;
if (msg.what == LIST_API_CLIENTS) {
activity.listApClients();
} else if (msg.what == UPDATE_AP_STATUS) {
activity.updateApStatus();
} }}}
答案 0 :(得分：1)
看到代码后，您忘了给布局文件充气。
请在此行super.onCreate(savedInstanceState);下添加以下代码，并带有正确的布局文件引用。
setContentView(R.layout.your_layout_id);
然后您的问题就会解决。
答案 1 :(得分：1)
在调用不同的视图（例如按钮，文本视图等）之前，您需要给活动视图充气。 您应该使用： setContentView（R.layout.activity_main）; //使用您自己的名称更改布局名称。
答案 2 :(得分：0)
尝试在空对象引用上调用虚拟方法'void android.widget.TextView.setOnClickListener（android.view.View $ OnClickListener）'
这意味着您带有clickListener的textview为null，需要与XML中的Textview绑定。 我认为代码将显示视图为null的地方。