android - 尝试使用 Fragment 创建聊天？

Question

我正在尝试使用 Fragment 创建聊天。为此，我在谷歌上找到了一个例子。该项目使用 Activity，我正在尝试使用 Fragment，因为我的项目都是使用 Fragments 开发的。当我从 Activity 更改为 Fragment 这一行时:adapter = new DiscussArrayAdapter(getView().getContext(), R.layout.listitem_discuss); 抛出异常

这是我的尝试

XML

///activity_discuss
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <ListView
        android:id="@+id/listView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="80dp">
    </ListView>

    <RelativeLayout
        android:id="@+id/form"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:orientation="vertical" >

        <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:inputType="textMultiLine"
            android:ems="10"
            android:id="@+id/chatText"
            android:layout_alignParentBottom="true"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:layout_toLeftOf="@+id/buttonSend" />

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Send"
            android:id="@+id/buttonSend"
            android:layout_alignBottom="@+id/chatText"
            android:layout_alignParentRight="true"
            android:layout_alignParentEnd="true" />
    </RelativeLayout>

</RelativeLayout>


///listitem_discuss
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" >

    <LinearLayout
        android:id="@+id/wrapper"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" >

        <TextView
            android:id="@+id/comment"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_margin="5dip"
            android:background="@drawable/bubble_yellow"
            android:paddingLeft="10dip"
            android:text="Hello bubbles!"
            android:textColor="@android:color/primary_text_light" />
    </LinearLayout>

</LinearLayout>

fragment

public class HelloBubblesActivity extends Fragment {
    private DiscussArrayAdapter adapter;
    private ListView lv;
    private LoremIpsum ipsum;
    private EditText editText1;
    private Button btnSend;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.activity_discuss, container, false);
        lv = (ListView)getView().findViewById(R.id.listView1);

        adapter = new DiscussArrayAdapter(getView().getContext(), R.layout.listitem_discuss);
        lv.setAdapter(adapter);

        editText1 = (EditText)view.findViewById(R.id.chatText);
        editText1.setOnKeyListener(new OnKeyListener() {
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                // If the event is a key-down event on the "enter" button
                if ((event.getAction() == KeyEvent.ACTION_DOWN) && (keyCode == KeyEvent.KEYCODE_ENTER)) {
                    // Perform action on key press
                    //adapter.add(new OneComment(false, editText1.getText().toString()));
                    receiveMessage();
                    editText1.setText("");
                    return true;
                }
                return false;
            }
        });

        btnSend = (Button)view.findViewById(R.id.buttonSend);
        btnSend.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //adapter.add(new OneComment(false, editText1.getText().toString()));
                receiveMessage();
                editText1.setText("");
            }
        });

        return  view;
    }




    private void receiveMessage(){
        String msg = editText1.getText().toString();
        new ChatDAO().receiveMessage("");
    }


    /** recebe msg */
    private void addItems() {
        adapter.add(new OneComment(true, "Hello bubbles!"));
    }

}

适配器

public class DiscussArrayAdapter extends ArrayAdapter<OneComment> {

    private TextView countryName;
    private List<OneComment> countries = new ArrayList<OneComment>();
    private LinearLayout wrapper;

    public DiscussArrayAdapter(Context context, int resource) {
        super(context, resource);
    }

    @Override
    public void add(OneComment object) {
        countries.add(object);
        super.add(object);
    }



    public int getCount() {
        return this.countries.size();
    }

    public OneComment getItem(int index) {
        return this.countries.get(index);
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        View row = convertView;
        if (row == null) {
            LayoutInflater inflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            row = inflater.inflate(R.layout.listitem_discuss, parent, false);
        }

        wrapper = (LinearLayout) row.findViewById(R.id.wrapper);

        OneComment coment = getItem(position);

        countryName = (TextView) row.findViewById(R.id.comment);

        countryName.setText(coment.comment);

        countryName.setBackgroundResource(coment.left ? R.drawable.bubble_yellow : R.drawable.bubble_green);
        wrapper.setGravity(coment.left ? Gravity.LEFT : Gravity.RIGHT);

        return row;
    }

    public Bitmap decodeToBitmap(byte[] decodedByte) {
        return BitmapFactory.decodeByteArray(decodedByte, 0, decodedByte.length);
    }

}

Answer 1

此时在您的代码中，getView() 将返回 null，因为从 onCreateView() 方法返回的 View 被设置为 Fragment 的看法。使用 getActivity() 而不是 getView().getContext() 来获取必要的上下文。