為什么開始新活動時我的android應用程序崩潰？

Question

嘗試啟動新活動（uploadLocation.class）時，我的應用程序不斷崩潰。 沒有突出顯示錯誤，並且我無法在uploadLocation類中進行調試。

我已向清單添加權限

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

主要活動

當執行MainActivity的這段代碼時，應用程序崩潰了。

public void uploadMyLocation (View view){
    startActivity(new Intent(this, uploadLocation.class));
}

除了該類以外，其他類都應該工作（下面完整的MainActivity.java）

import android.content.Context;
import android.content.Intent;
import android.location.Location;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;

public class MainActivity extends AppCompatActivity implements GoogleApiClient.ConnectionCallbacks,
    GoogleApiClient.OnConnectionFailedListener, LocationListener {

Button uploadButton;
TextView latitudeView, longitudeView, networkView;
Location lastKnownLocation;
private GoogleApiClient googleApiClient;
private LocationRequest locationRequest;
String latString1, lonString1;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    uploadButton = (Button) findViewById(R.id.uploadButton);
    networkView = (TextView) findViewById(R.id.networkView);

    latitudeView = (TextView)findViewById(R.id.latitudeView);
    longitudeView = (TextView)findViewById(R.id.longitudeView);

    buildGoogleApiClient();

    ConnectivityManager connectivityManager = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
    if (networkInfo != null && networkInfo.isConnected()){
        networkView.setVisibility(View.INVISIBLE);
    } else {
        uploadButton.setEnabled(false);
    }


}

public void uploadMyLocation (View view){
    startActivity(new Intent(this, uploadLocation.class));
}

@Override
public void onConnected(Bundle bundle) {
    locationRequest = LocationRequest.create();
    locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    locationRequest.setInterval(100); // location updated every second

    LocationServices.FusedLocationApi.requestLocationUpdates(googleApiClient, locationRequest, this);
    lastKnownLocation = LocationServices.FusedLocationApi.getLastLocation(googleApiClient);

    if(lastKnownLocation != null){
        latString1 = String.valueOf(lastKnownLocation.getLatitude());
        lonString1 = String.valueOf(lastKnownLocation.getLongitude());
    }
    updateUI();
}

@Override
public void onLocationChanged(Location location) {
    latString1 = String.valueOf(location.getLatitude());
    lonString1 = String.valueOf(location.getLongitude());
    updateUI();
}



@Override
public void onConnectionSuspended(int i) {

}

@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
    buildGoogleApiClient();
}

synchronized void buildGoogleApiClient(){
    googleApiClient = new GoogleApiClient.Builder(this).addConnectionCallbacks(this).addOnConnectionFailedListener(this).addApi(LocationServices.API).build();
}

@Override
protected void onStart(){
    super.onStart();
    googleApiClient.connect();
}

@Override
protected void onDestroy(){
    super.onDestroy();
    googleApiClient.disconnect();
}

void updateUI(){
    latitudeView.setText(latString1);
    longitudeView.setText(lonString1);
}
}

uploadLocation

import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
import java.net.URLEncoder;

public class uploadLocation extends AppCompatActivity {

TextView myLatitudeView, myLongitudeView, latitudeView, longitudeView;
String latString, lonString;

public void uploadInfo(View view){
    latString = latitudeView.getText().toString();
    lonString = longitudeView.getText().toString();
    myLatitudeView = (TextView)findViewById(R.id.myLatitudeView);
    myLongitudeView = (TextView)findViewById(R.id.myLongitudeView);
    myLatitudeView.setText(latString);
    myLongitudeView.setText(lonString);
    BackgroundOp backgroundOp = new BackgroundOp();
    backgroundOp.execute(latString, lonString);
    finish();
}

class BackgroundOp extends AsyncTask<String, Void, String>{

    String myUrl;

    @Override
    protected void onPreExecute() {
        myUrl = "http://[web address]/[php script]";
    }

    @Override
    protected String doInBackground(String... data) {
        String latString, lonString;
        latString = data [0];
        lonString = data [1];

        try {
            URL url = new URL(myUrl);
            HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
            httpURLConnection.setRequestMethod("POST");
            httpURLConnection.setDoOutput(true);
            OutputStream outputStream = httpURLConnection.getOutputStream();
            BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
            String myDataStream = URLEncoder.encode("Latitude", "UTF-8") + "=" + URLEncoder.encode(latString, "UTF-8") + "&" +
                    URLEncoder.encode("Longitude", "UTF-8") + "=" + URLEncoder.encode(lonString, "UTF-8");
            bufferedWriter.write(myDataStream);
            bufferedWriter.flush();
            bufferedWriter.close();
            outputStream.close();
            InputStream inputStream = httpURLConnection.getInputStream();
            inputStream.close();
            httpURLConnection.disconnect();
            return "Upload Successful";

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (ProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
    protected void onProgressUpdate(Void... values) {
        super.onProgressUpdate(values);
    }

    @Override
    protected void onPostExecute(String result) {
        Toast.makeText(getApplicationContext(), result, Toast.LENGTH_LONG).show();
    }
}
}

XML文件

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Upload Location"
    android:id="@+id/uploadButton"
    android:layout_marginBottom="61dp"
    android:layout_above="@+id/networkView"
    android:layout_centerHorizontal="true"
    android:onClick="uploadInfo" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Get Data"
    android:id="@+id/getDataButton"
    android:onClick="uploadMyLocation"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="41dp" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="[Latitude]"
    android:id="@+id/latitudeView"
    android:layout_centerVertical="true"
    android:layout_toStartOf="@+id/uploadButton" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="[Longitude]"
    android:id="@+id/longitudeView"
    android:layout_alignTop="@+id/latitudeView"
    android:layout_toEndOf="@+id/uploadButton" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="[My Latitude]"
    android:id="@+id/myLatitudeView"
    android:layout_below="@+id/getDataButton"
    android:layout_toStartOf="@+id/getDataButton" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="[My Longitude]"
    android:id="@+id/myLongitudeView"
    android:layout_below="@+id/getDataButton"
    android:layout_toEndOf="@+id/getDataButton" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="[Network Unavailable]"
    android:id="@+id/networkView"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:layout_marginBottom="169dp" />

編譯器日志：

   03-24 16:11:26.893 17436-17436/? I/art: Late-enabling -Xcheck:jni
03-24 16:11:27.044 17436-17467/com.cityuni.sophie.locationapp I/GMPM: App measurement is starting up
03-24 16:11:27.058 17436-17467/com.cityuni.sophie.locationapp E/GMPM: getGoogleAppId failed with status: 10
03-24 16:11:27.059 17436-17467/com.cityuni.sophie.locationapp E/GMPM: Uploading is not possible. App measurement disabled
03-24 16:11:27.155 17436-17475/com.cityuni.sophie.locationapp D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
03-24 16:11:27.160 17436-17436/com.cityuni.sophie.locationapp D/Atlas: Validating map...
03-24 16:11:27.208 17436-17475/com.cityuni.sophie.locationapp I/Adreno: QUALCOMM build                   : 40d, I21dda
                                                                        Build Date                       : 08/24/15
                                                                        OpenGL ES Shader Compiler Version: E031.25
                                                                        Local Branch                     : 
                                                                        Remote Branch                    : quic/LA.4.1.1_r9
                                                                        Remote Branch                    : NONE
                                                                        Reconstruct Branch               : NOTHING
03-24 16:11:27.216 17436-17475/com.cityuni.sophie.locationapp I/OpenGLRenderer: Initialized EGL, version 1.4
03-24 16:11:27.225 17436-17475/com.cityuni.sophie.locationapp D/OpenGLRenderer: Enabling debug mode 0
03-24 16:11:27.388 17436-17436/com.cityuni.sophie.locationapp I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@3563b026 time:407225888
03-24 16:11:45.883 17436-17436/com.cityuni.sophie.locationapp D/AndroidRuntime: Shutting down VM
03-24 16:11:45.902 17436-17436/com.cityuni.sophie.locationapp E/AndroidRuntime: FATAL EXCEPTION: main
                                                                                Process: com.cityuni.sophie.locationapp, PID: 17436
                                                                                java.lang.IllegalStateException: Could not find method uploadInfo(View) in a parent or ancestor Context for android:onClick attribute defined on view class android.support.v7.widget.AppCompatButton with id 'uploadButton'
                                                                                    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:325)
                                                                                    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:284)
                                                                                    at android.view.View.performClick(View.java:4861)
                                                                                    at android.view.View$PerformClick.run(View.java:19980)
                                                                                    at android.os.Handler.handleCallback(Handler.java:739)
                                                                                    at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                    at android.os.Looper.loop(Looper.java:211)
                                                                                    at android.app.ActivityThread.main(ActivityThread.java:5373)
                                                                                    at java.lang.reflect.Method.invoke(Native Method)
                                                                                    at java.lang.reflect.Method.invoke(Method.java:372)
                                                                                    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1020)
                                                                                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:815)
03-24 16:12:19.041 17436-17436/com.cityuni.sophie.locationapp I/Process: Sending signal. PID: 17436 SIG: 9

Answer 1

為了通知您，每個活動都需要根據文檔覆蓋onCreate()方法

活動開始時調用此方法。 這是大多數初始化應該去的地方：調用setContentView(int)來膨脹活動的UI，使用findViewById(int)與UI中的小部件進行編程交互

我建議您重寫必要的方法，也不要忘記在onCreate()方法中調用super.onCreate() 。

更新：

我發現了您的錯誤，這是由於此屬性

android:onClick="uploadInfo"

因為您提供的XML是activity_main.xml 。 然后在另一個Activity中創建方法uploadInfo 。 因此，我建議您要么刪除此屬性，要么在MainActivity而不是uploadLocation活動中創建uploadInfo方法。

要獲取提示，您可以在該屬性上按Alt + Enter並按照Android Studio的建議創建方法uploadInfo。

Answer 2

我認為您尚未將新活動添加到android清單文件中。 嘗試添加它。

<activity android:name=".uploadLocation">
</activity>

Answer 3

當我開始在Android上進行開發時，我遇到了同樣的問題，並使用它來修復我的應用崩潰：

請嘗試擴展Activity，而不是擴展AppCompatActivity。

如果不起作用，也許您有一個Component null，請檢查您實例化XML中聲明的所有組件。