java - 为什么我的 Android 应用程序在启动新 Activity 时崩溃？

Question

当我尝试启动新 Activity (uploadLocation.class)时，我的应用程序不断崩溃。没有突出显示任何错误，并且我无法在 uploadLocation 类中进行调试。

我已向我的 list 添加了权限

<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 Activity

当执行 MainActivity 中的这部分代码时，应用程序崩溃了。

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

除了该类按其应有的方式工作之外(完成下面的 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);
}
}

上传位置

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" />

编译器日志:

   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

谨通知您每个 Activity 都需要覆盖 onCreate()方法按照文档

This method is Called when the activity is starting. This is where most initialization should go: calling setContentView(int) to inflate the activity's UI, using findViewById(int) to programmatically interact with widgets in the UI

我建议您重写必要的方法，并且不要忘记在 onCreate() 方法中调用 super.onCreate() 。

更新:

我发现了你的错误，那是因为这个属性

android:onClick="uploadInfo"

因为您提供的XML是activity_main.xml。并且您正在另一个 Activity 中创建方法 uploadInfo。因此，我建议您要么删除此属性，要么在 MainActivity 中而不是在 uploadLocation Activity 中创建 uploadInfo 方法。

要获得提示，您可以在该属性上按 Alt+Enter 并按照 Android Studio 的建议创建方法 uploadInfo。