java - 索引越界异常 - 意外错误

Question

除此之外，我正在处理 Parse.com 集成和 Sinch.com 即时消息集成。单击列表项后，会显示意外错误，特别是下面是日志消息。单击后，它应该将您引导至即时消息 Activity ，但是我收到了以下错误。

08-07 16:49:44.810: E/AndroidRuntime(11444): FATAL EXCEPTION: main
08-07 16:49:44.810: E/AndroidRuntime(11444): Process: com.dooba.beta, PID: 11444
08-07 16:49:44.810: E/AndroidRuntime(11444): java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
08-07 16:49:44.810: E/AndroidRuntime(11444):    at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at java.util.ArrayList.get(ArrayList.java:308)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at com.dooba.beta.MatchingActivity$3.done(MatchingActivity.java:90)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at com.parse.FindCallback.internalDone(FindCallback.java:45)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at com.parse.FindCallback.internalDone(FindCallback.java:1)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at com.parse.Parse$6$1.run(Parse.java:888)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at android.os.Handler.handleCallback(Handler.java:733)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at android.os.Handler.dispatchMessage(Handler.java:95)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at android.os.Looper.loop(Looper.java:136)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at android.app.ActivityThread.main(ActivityThread.java:5017)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at java.lang.reflect.Method.invokeNative(Native Method)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at java.lang.reflect.Method.invoke(Method.java:515)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
08-07 16:49:44.810: E/AndroidRuntime(11444):    at dalvik.system.NativeStart.main(Native Method)

下面是 Activity 代码

public class MatchingActivity extends Activity {


    private String currentUserId;
    private ArrayAdapter<String> namesArrayAdapter;
    private ArrayList<String> names;
    private ListView usersListView;
    private Button logoutButton;

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

        logoutButton = (Button) findViewById(R.id.logoutButton);
        logoutButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                ParseUser.logOut();
                Intent intent = new Intent(getApplicationContext(), LoginActivity.class);
                startActivity(intent);
            }
        });

        setConversationsList();
    }

    private void setConversationsList() {
        currentUserId = ParseUser.getCurrentUser().getObjectId();
        names = new ArrayList<String>();

        ParseQuery<ParseUser> query = ParseUser.getQuery();
        query.whereNotEqualTo("name", currentUserId);
        query.findInBackground(new FindCallback<ParseUser>() {
            public void done(List<ParseUser> userList, ParseException e) {
                if (e == null) {
                    for (int i=0; i<userList.size(); i++) {
                        names.add(userList.get(i).getUsername().toString());
                    }

                    usersListView = (ListView)findViewById(R.id.usersListView);
                    namesArrayAdapter =
                        new ArrayAdapter<String>(getApplicationContext(),
                            R.layout.user_list_item, names);
                    usersListView.setAdapter(namesArrayAdapter);

                    usersListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                        @Override
                        public void onItemClick(AdapterView<?> a, View v, int i, long l) {
                            openConversation(names, i);
                        }
                    });

                } else {
                    Toast.makeText(getApplicationContext(),
                        "Error loading user list",
                            Toast.LENGTH_LONG).show();
                }
            }
        });
    }

    public void openConversation(ArrayList<String> names, int pos) {
        ParseQuery<ParseUser> query = ParseUser.getQuery();
        query.whereEqualTo("name", names.get(pos));
        query.findInBackground(new FindCallback<ParseUser>() {
           public void done(List<ParseUser> user, ParseException e) {
               if (e == null) {
                   Intent intent = new Intent(getApplicationContext(), MessagingActivity.class);
                   intent.putExtra("RECIPIENT_ID", user.get(0).getObjectId());
                   startActivity(intent);
               } else {
                   Toast.makeText(getApplicationContext(),
                       "Error finding that user",
                           Toast.LENGTH_SHORT).show();
               }
           }
        });
    }
}

下面是即时通讯 Activity

public class MessagingActivity extends Activity implements ServiceConnection, MessageClientListener {

    private String recipientId;
    private Button sendButton;
    private EditText messageBodyField;
    private String messageBody;
    private MessageService.MessageServiceInterface messageService;
    private MessageAdapter messageAdapter;
    private ListView messagesList;

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

        doBind();

        messagesList = (ListView) findViewById(R.id.listMessages);
        messageAdapter = new MessageAdapter(this);
        messagesList.setAdapter(messageAdapter);

        Intent intent = getIntent();
        recipientId = intent.getStringExtra("RECIPIENT_ID");

        messageBodyField = (EditText) findViewById(R.id.messageBodyField);
        sendButton = (Button) findViewById(R.id.sendButton);

        sendButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                sendMessage();
            }
        });
    }

    private void sendMessage() {
        messageBody = messageBodyField.getText().toString();
        if (messageBody.isEmpty()) {
            Toast.makeText(this, "Please enter a message", Toast.LENGTH_LONG).show();
            return;
        }

        messageService.sendMessage(recipientId, messageBody);
        messageBodyField.setText("");
    }

    private void doBind() {
        Intent serviceIntent = new Intent(this, MessageService.class);
        bindService(serviceIntent, this, BIND_AUTO_CREATE);
    }

    @Override
    public void onDestroy() {
        unbindService(this);
        super.onDestroy();
    }

    @Override
    public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
        //Define the messaging service and add a listener
        messageService = (MessageService.MessageServiceInterface) iBinder;
        messageService.addMessageClientListener(this);
        if (!messageService.isSinchClientStarted()) {
            Toast.makeText(this, "The message client did not start."
                ,Toast.LENGTH_LONG).show();
        }
    }

    @Override
    public void onServiceDisconnected(ComponentName componentName) {
        messageService = null;
    }

    @Override
    public void onMessageDelivered(MessageClient client, MessageDeliveryInfo deliveryInfo) {
        //Intentionally  left blank
    }

    @Override
    public void onMessageFailed(MessageClient client, Message message,
                                MessageFailureInfo failureInfo) {
        //Notify the user if message fails to send
        Toast.makeText(this, "Message failed to send.", Toast.LENGTH_LONG).show();
    }

    @Override
    public void onIncomingMessage(MessageClient client, Message message) {
        messageAdapter.addMessage(message, MessageAdapter.DIRECTION_INCOMING);
    }

    @Override
    public void onMessageSent(MessageClient client, Message message, String recipientId) {
        messageAdapter.addMessage(message, MessageAdapter.DIRECTION_OUTGOING);
    }

    @Override
    public void onShouldSendPushData(MessageClient client, Message message, List<PushPair> pushPairs) {
        //Intentionally left blank
    }
}

我的另一个问题是它在列表中返回 OjectID，我更希望它返回 User 类的“name”、“headline”和“age”列。

如果您需要更多信息，请告诉我。提前致谢。

Answer 1

根据cat日志我们可以确定问题的根源，即MatchingActivity.done中的第90行。

08-07 16:49:44.810: E/AndroidRuntime(11444): at com.dooba.beta.MatchingActivity$3.done(MatchingActivity.java:90)

你的问题出在这个方法上:

public void openConversation(ArrayList<String> names, int pos) {
    ParseQuery<ParseUser> query = ParseUser.getQuery();
    query.whereEqualTo("name", names.get(pos));
    query.findInBackground(new FindCallback<ParseUser>() {
       public void done(List<ParseUser> user, ParseException e) {
           if (e == null) {
               Intent intent = new Intent(getApplicationContext(), MessagingActivity.class);
               //Below is line 90:
               intent.putExtra("RECIPIENT_ID", user.get(0).getObjectId());
               startActivity(intent);
           } else {
               Toast.makeText(getApplicationContext(),
                   "Error finding that user",
                       Toast.LENGTH_SHORT).show();
           }
       }
    });
}

来源是 IndexOutOfBoundsException，访问不存在的索引。在第 90 行，我们收到以下调用:

intent.putExtra("RECIPIENT_ID", user.get(0).getObjectId());

我们只能在一个地方访问这一行中的索引，这里:

user.get(0).getObjectId()

因此，我们可以假设列表user的大小为0，当访问列表中的索引时，请确保用户列表足够大。像这样:

if(!user.isEmpty()){
     //the List user contains a user
     Intent intent = new Intent(getApplicationContext(), MessagingActivity.class);
     intent.putExtra("RECIPIENT_ID", user.get(0).getObjectId());
     startActivity(intent);
} else {
     //the List user is empty do what you wish.
}