问题描述
我的应用程序显示了 NetworkOnMainThreadException 在日志猫。
于是我找到了AsyncTask的方法来卸载网络操作后台线程。
加入AsyncTask.It节目后 ViewRootImpl $ CalledFromWrongThreadException 。所以我必须使用 onPostExecute 。结果
我学会了 Asyntack 文档和电子tried.Now我被困它没有返回正确output.I不知道我是否在宣布它各自的方法的。
My App shows a NetworkOnMainThreadException in the Log Cat.So I found the Asynctask Method to offload network operations to a background thread.After adding the AsyncTask.It shows ViewRootImpl$CalledFromWrongThreadException.So i have to use onPostExecute.
I learnt the Asyntack Docs & tried.Now i got Stuck it is not Returning the correct output.I don't know whether i declared it under the respective Method's.
我要显示在的TextView 电视处理的文本
I want to display the processed Text in the Textview tv
所以帮我在正确的方向：）
So Help me in the Right Direction :)
感谢您的帮助...
WifiApManager
public class WifiApManager {
private final WifiManager mWifiManager;
public WifiApManager(Context context) {
mWifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
}
public boolean setWifiApEnabled(WifiConfiguration wifiConfig, boolean enabled) {
try {
if (enabled) { // disable WiFi in any case
mWifiManager.setWifiEnabled(false);
}
Method method = mWifiManager.getClass().getMethod("setWifiApEnabled", WifiConfiguration.class, boolean.class);
return (Boolean) method.invoke(mWifiManager, wifiConfig, enabled);
} catch (Exception e) {
Log.e(this.getClass().toString(), "wifi", e);
return false;
}
}
public WIFI_AP_STATE getWifiApState() {
try {
Method method = mWifiManager.getClass().getMethod("getWifiApState");
int tmp = ((Integer)method.invoke(mWifiManager));
// Fix for Android 4
if (tmp > 10) {
tmp = tmp - 10;
}
return WIFI_AP_STATE.class.getEnumConstants()[tmp];
} catch (Exception e) {
Log.e(this.getClass().toString(), "wifi", e);
return WIFI_AP_STATE.WIFI_AP_STATE_FAILED;
}
}
public boolean isWifiApEnabled() {
return getWifiApState() == WIFI_AP_STATE.WIFI_AP_STATE_ENABLED;
}
public WifiConfiguration getWifiApConfiguration() {
try {
Method method = mWifiManager.getClass().getMethod("getWifiApConfiguration");
return (WifiConfiguration) method.invoke(mWifiManager);
} catch (Exception e) {
Log.e(this.getClass().toString(), "wifi", e);
return null;
}
}
public boolean setWifiApConfiguration(WifiConfiguration wifiConfig) {
try {
Method method = mWifiManager.getClass().getMethod("setWifiApConfiguration", WifiConfiguration.class);
return (Boolean) method.invoke(mWifiManager, wifiConfig);
} catch (Exception e) {
Log.e(this.getClass().toString(), "wifi", e);
return false;
}
}
public ArrayList<ClientScanResult> getClientList(boolean onlyReachables) {
return getClientList(onlyReachables, 10);
}
public ArrayList<ClientScanResult> getClientList(boolean onlyReachables, int reachableTimeout) {
BufferedReader br = null;
ArrayList<ClientScanResult> result = null;
try {
result = new ArrayList<ClientScanResult>();
br = new BufferedReader(new FileReader("/proc/net/arp"));
String line;
while ((line = br.readLine()) != null) {
String[] splitted = line.split(" +");
if ((splitted != null) && (splitted.length >= 4)) {
// Basic sanity check
String mac = splitted[3];
if (mac.matches("..:..:..:..:..:..")) {
boolean isReachable = InetAddress.getByName(splitted[0]).isReachable(reachableTimeout);
if (!onlyReachables || isReachable) {
result.add(new ClientScanResult(splitted[0], splitted[3], splitted[5], isReachable));
}
}
}
}
} catch (Exception e) {
Log.e(LOGTAG, e.toString());
} finally {
try {
br.close();
} catch (IOException e) {
Log.e(LOGTAG, e.toString());
}
}
return result;
}
}
connect.java
public class connect extends Activity{
WifiApManager wifiApManager;
TextView tv;
Button scan;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.connect);
tv =(TextView) findViewById(R.id.iptv);
scan myScan = new scan(this); // pass the context to the constructor
myScan.execute();
}
class scan extends AsyncTask<String, Void, Void> {
public Context context;
ArrayList<ClientScanResult> clients;
public scan(Context c) // constructor to take Context
{
context = c; // Initialize your Context variable
}
protected Void doInBackground(String... params) {
wifiApManager = new WifiApManager(context); // use the variable here
clients = wifiApManager.getClientList(false);
return null;
}
}
protected void onPostExecute(Void result){
ArrayList<ClientScanResult> clients;
tv.setText("WifiApState: " + wifiApManager.getWifiApState() + "\n\n");
tv.append("Clients: \n");
for (ClientScanResult clientScanResult : clients) //showin error in clients
{
tv.append("####################\n");
tv.append("IpAddr: " + clientScanResult.getIpAddr() + "\n");
tv.append("Device: " + clientScanResult.getDevice() + "\n");
tv.append("HWAddr: " + clientScanResult.getHWAddr() + "\n");
tv.append("isReachable: " + clientScanResult.isReachable()+ "\n");
}
}
}
注意：
它显示了在客户端上的变量的方法onPostExecute在connect.java一个错误。
Note:It shows a error in connect.java on onPostExecute Method in Clients Variable.
推荐答案
在您的onPostExecute（......），你有
in your onPostExecute(...) you have
ArrayList<ClientScanResult> **clients**;
然后
for (ClientScanResult clientScanResult : **clients**) //showin error in clients
客户为空，因此永远不会执行循环。你不需要定义一个新的ArrayList，因为你已经有一个在扫描类定义为一个全局变量
clients is null therefore the loop is never executed. you don't need to define a new ArrayList since you already have one defined as a global variable in the scan class
有一个更好的办法来做到这一点是设置doInBackground的返回类型为ArrayList的＆LT; ClientScanResult>然后你有onPostExecute采取一个ArrayList＆LT; ClientScanResult>
A better way to do this is to set the return type of doInBackground to ArrayList< ClientScanResult> and then you have onPostExecute take an ArrayList< ClientScanResult>
class scan extends AsyncTask<Void, Void, ArrayList<ClientScanResult>> {
protected ArrayList<ClientScanResult> doInBackground(Void... params) {
wifiApManager = new WifiApManager(context); // use the variable here
return wifiApManager.getClientList(false);
}
protected void onPostExecute(ArrayList<ClientScanResult> clients){
tv.setText("WifiApState: " + wifiApManager.getWifiApState() + "\n\n");
tv.append("Clients: \n");
for (ClientScanResult clientScanResult : clients) //showin error in clients
{
tv.append("####################\n");
tv.append("IpAddr: " + clientScanResult.getIpAddr() + "\n");
tv.append("Device: " + clientScanResult.getDevice() + "\n");
tv.append("HWAddr: " + clientScanResult.getHWAddr() + "\n");
tv.append("isReachable: " + clientScanResult.isReachable()+ "\n");
}
}
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