java - 使用自定义 ListView 时出错

Question

我一直在学习一些教程来制作 twitter 应用程序，但遇到了有关列表中自定义布局的问题。更具体地说，该列表没有更新，保留在以前的版本上，如图所示(在此版本中输入了空白字符串数组，而不是 Tweet pojos 数组):

我遇到问题的教程特定部分的链接是 here 。 (我遇到问题的步骤是步骤 3)。

这是我的代码

TweetListActivity.java:

public class TweetListActivity extends ListActivity {

private TweetAdapter tweetItemArrayAdapter;
private List<Tweet> tweets = new ArrayList<Tweet>();


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

      for ( int i = 0; i < 20; i++ ) {
            Tweet tweet = new Tweet();
            tweet.setTitle("A nice header for Tweet # " +i);
            tweet.setBody("Some random body text for the tweet # " +i);
            tweets.add(tweet);
        }

      tweetItemArrayAdapter = new TweetAdapter(this, tweets);
      setListAdapter(tweetItemArrayAdapter);


}
@Override
 protected void onListItemClick(ListView l, View v, int position, long id) {
     Intent intent = new Intent(this, TweetDetailActivity.class);
     startActivity(intent);
 }

TweetAdapter.java:

public class TweetAdapter extends ArrayAdapter<Tweet>{

private LayoutInflater inflater;

public TweetAdapter(Activity activity, List<Tweet> tweets){
    super(activity, R.layout.row_tweet, tweets);
    inflater = activity.getWindow().getLayoutInflater();
}

@SuppressLint("ViewHolder") @Override
public View getView(int position, View convertView, ViewGroup parent){
    return inflater.inflate(R.layout.row_tweet, parent, false);
}

activity_tweet.xml:

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
        tools:context="org.codelearn.twitter.TweetListActivity" >

        <ListView
            android:id="@android:id/list"
            android:layout_width="match_parent"
            android:layout_height="match_parent" >
        </ListView> 

    </RelativeLayout>

row_tweet.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:src="@drawable/user_profile"
        android:layout_marginLeft="5dp"
        android:layout_marginTop="5dp" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:layout_marginLeft="10dp"
        android:gravity="left" >

        <TextView
            android:id="@+id/tweetTitle"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Header Text"
            android:textAppearance="?android:attr/textAppearanceLarge"
            android:textSize="19sp"
            android:textColor="#222222"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/textView2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Tweet Body Text Here"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:layout_marginTop="5dp"
            android:ellipsize="end"
            android:lines="3"
            android:textColor="#666666"                                                
            android:textSize="14sp" />

        <TextView
            android:id="@+id/textView3"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="20 Nov 2013"
            android:textAppearance="?android:attr/textAppearanceSmall"
            android:layout_marginTop="5dp"
            android:textColor="#999999"
            android:textSize="12sp" />

    </LinearLayout>

</LinearLayout>

感谢您的帮助。

Answer 1

你可以做这样的事情。请看看这个 http://theopentutorials.com/post/uncategorized/android-custom-listview-with-image-and-text-using-arrayadapter/

List<Tweet> _tweets;
    Activity _activity;
    public TweetAdapter(Activity activity, List<Tweet> tweets){
        super(activity, R.layout.row_tweet, tweets);
        inflater = activity.getWindow().getLayoutInflater();
        this._tweets = tweets;
        this._activity = activity;
    }

    public class ViewHolder {
        TextView tvTitle = null;
        TextView tvTweetBody = null;
    }

在你的 getView() 中。您需要添加以下内容:

@Override
        public View getView(final int position, View convertView, ViewGroup parent){
            ViewHolder _viewHolder = new ViewHolder();
            Tweet _bean = _tweets.get(position);
            if (convertView == null) {
                LayoutInflater _layInflater = (LayoutInflater) _activity .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                convertView = _layInflater.inflate(R.layout.row_tweet, null);


                // Lookup view for data population
                _viewHolder.tvTitle = (TextView) convertView.findViewById(R.id.tweetTitle);
                _viewHolder.tvTweetBody = (TextView) convertView.findViewById(R.id.textView2);
    convertView.setTag(_viewHolder);

            } else {
                _viewHolder = (ViewHolder) convertView.getTag();
            }

            // Populate the data into the template view using the data object
            tvTitle.setText(_bean.getTitle());
            tvTweetBody .setText(_bean.getBody());

            return convertView;

        }