Question

我有一个来自我的两个用户的消息列表，并希望将这些消息显示为两个不同颜色和定位的聊天气泡。使用我当前的代码，我的所有消息都会毫无问题地填充到列表视图中，只有颜色和定位无法正常工作。

在我的Activity中，我有以下代码在onCreate（）上调用：

public void populateMessages() {
    SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
    String currentUser = sharedPrefs.getString("Username", null);
    DatabaseReference mRef = FirebaseDatabase.getInstance().getReferenceFromUrl(Passwords.FB_URL).child("Message").child(currentUser).child(binderContact.getNumber());
    time = System.currentTimeMillis();
    Query queryRef = mRef.orderByChild("time").startAt(time);
    adapter = new MessageAdapter(this, Message.class, R.layout.message_list_row, queryRef);
    ListView lv = (ListView) findViewById(R.id.list_view_chalkboard);
    lv.setAdapter(adapter);
}

这是我的XML布局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/layout"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:padding="8dp">
    <ImageView
        android:id="@+id/message_type"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_alarm_grey600_18dp"
        android:layout_alignParentTop="true"
        android:layout_alignLeft="@+id/message"
        android:layout_alignStart="@+id/message"
        />
    <TextView
        android:id="@+id/message_time"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:singleLine="true"
        android:text="YESTERDAY"
        android:textSize="12sp"
        android:layout_alignBottom="@+id/message_type"
        android:layout_toRightOf="@+id/message_type"
        android:layout_toEndOf="@+id/message_type"
        android:layout_marginLeft="6dp"
        android:layout_marginStart="6dp"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"/>

    <TextView
        android:id="@+id/message"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/chat_bubble2"
        android:gravity="center"
        android:text="Test"
        android:textIsSelectable="false"
        android:textSize="18sp"
        android:layout_below="@+id/message_time"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />
    </RelativeLayout>

这是我的FirebaseListAdapter：

public class MessageAdapter extends FirebaseListAdapter<Message> {
    private String currentUser;
    RelativeLayout.LayoutParams params;
    public MessageAdapter(Activity activity, Class<Message> messageClass, int modelLayout, Query ref) {
        super(activity, messageClass, modelLayout, ref);
    }
    @Override
    protected void populateView(View view, Message m, int i) {
        TextView messageTime = (TextView)view.findViewById(R.id.message_time);

        long time = m.getTime();
        TimeZone tz = TimeZone.getDefault();
        Calendar now = Calendar.getInstance();
        Calendar msgTime = Calendar.getInstance();
        msgTime.setTimeInMillis(time);
        SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(view.getContext());
        currentUser = sharedPrefs.getString("Username", null);
        TextView msg = (TextView)view.findViewById(R.id.message);
        if (m.getFrom() == currentUser) {
            msg.setBackgroundResource(R.drawable.chat_bubble2);
            params = (RelativeLayout.LayoutParams)msg.getLayoutParams();
            params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
            params.addRule(RelativeLayout.ALIGN_PARENT_END);
        }
        else {
            msg.setBackgroundResource(R.drawable.chat_bubble);
            params = (RelativeLayout.LayoutParams)msg.getLayoutParams();
            params.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
            params.addRule(RelativeLayout.ALIGN_PARENT_START);
        }
        msg.setLayoutParams(params);
        msg.setText(m.getText());
        if (now.get(Calendar.DATE) == msgTime.get(Calendar.DATE)) {
            Date date = new Date(time);
            DateFormat dateFormat = new SimpleDateFormat("HH:mm");
            dateFormat.setTimeZone(tz);
            String formattedDate = mActivity.getString(R.string.today) + dateFormat.format(date);
            messageTime.setText(formattedDate);
        }
        else if (msgTime.get(Calendar.DATE) - now.get(Calendar.DATE) == 1){
            Date date = new Date(time);
            DateFormat dateFormat = new SimpleDateFormat("HH:mm");
            dateFormat.setTimeZone(tz);
            String formattedDate = mActivity.getString(R.string.tomorrow) + dateFormat.format(date);
            messageTime.setText(formattedDate);
        }
        else {
            Date date = new Date(time);
            DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy HH:mm");
            dateFormat.setTimeZone(tz);
            String formattedDate = dateFormat.format(date);
            messageTime.setText(formattedDate);
        }

    }
}

Answer 1

我不知道你是否发现了这个问题，但正如Frank van Puffelen所说，你必须使用equals方法来比较java字符串。

所以，我建议你使用那个

if (m.getFrom().equals(currentUser)) {
        msg.setBackgroundResource(R.drawable.chat_bubble2);
        params = (RelativeLayout.LayoutParams)msg.getLayoutParams();
        params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
        params.addRule(RelativeLayout.ALIGN_PARENT_END);
    }

要比较日期，最好使用java方法：查看代码，了解两个日期是否相等，使用isEqual method。我建议你改变

if (now.get(Calendar.DATE).isEqual(msgTime.get(Calendar.DATE))) {
    // your code
}

而不是减去知道日期是否明天，而是使用isAfter方法

else if (msgTime.get(Calendar.DATE).isAfter(now.get(Calendar.DATE))){
    // your code
}

也请参阅此答案：How to compare dates in Java?我更喜欢 gstackoverflow 用户的答案。

如果我错了，请纠正我。

FirebaseUI适配器未正确填充ListView

1 个答案: