[英]Android JSON Data not parsing into ListView
Android未將JSON數據解析為ListView,我正在使用本教程,並且對ListViewAdapter.java進行了一些更改
就像在我的新實現中一樣,我使用了ViewHolder,我的代碼如下所示:
public class ListViewAdapter extends BaseAdapter {
// Declare Variables
Context context;
ArrayList<HashMap<String, String>> data;
ImageLoader imageLoader;
HashMap<String, String> resultp = new HashMap<String, String>();
ViewHolder holder;
public ListViewAdapter(Context context,
ArrayList<HashMap<String, String>> arraylist) {
this.context = context;
data = arraylist;
imageLoader = new ImageLoader(context);
}
@Override
public int getCount() {
return data.size();
}
@Override
public Object getItem(int position) {
return data.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
static class ViewHolder {
public ViewHolder(View convertView) {
// TODO Auto-generated constructor stub
}
TextView rank;
TextView country;
TextView population;
ImageView flag;
}
public View getView(final int position, View convertView, ViewGroup parent) {
// Declare Variables
// Avoid unneccessary calls to findViewById() on each row, which is expensive!
holder = null;
/*
* If convertView is not null, we can reuse it directly, no inflation required!
* We only inflate a new View when the convertView is null.
*/
if (convertView == null) {
convertView = ((Activity) context).getLayoutInflater().inflate(R.layout.listview_item, null);
// Create a ViewHolder and store references to the two children views
holder = new ViewHolder(convertView);
holder.rank = (TextView) convertView.findViewById(R.id.rank);
holder.country = (TextView) convertView.findViewById(R.id.country);
holder.population = (TextView) convertView.findViewById(R.id.population);
// Locate the ImageView in listview_item.xml
holder.flag = (ImageView) convertView.findViewById(R.id.flag);
// The tag can be any Object, this just happens to be the ViewHolder
convertView.setTag(holder);
} else {
// Get the ViewHolder back to get fast access to the TextView
// and the ImageView.
holder = (ViewHolder) convertView.getTag();
}
// Capture position and set results to the TextViews
holder.rank.setText(resultp.get(MainActivity.RANK));
holder.country.setText(resultp.get(MainActivity.COUNTRY));
holder.population.setText(resultp.get(MainActivity.POPULATION));
// Capture position and set results to the ImageView
// Passes flag images URL into ImageLoader.class
imageLoader.DisplayImage(resultp.get(MainActivity.FLAG), holder.flag);
// Capture ListView item click
return convertView;
}
}
編輯:單擊ListItem代碼
@Override
protected void onPostExecute(Void args) {
// Locate the listview in listview_main.xml
listview = (ListView) findViewById(R.id.listview);
// Pass the results into ListViewAdapter.java
adapter = new ListViewAdapter(MainActivity.this, arraylist);
// Set the adapter to the ListView
listview.setAdapter(adapter);
// Close the progressdialog
mProgressDialog.dismiss();
listview.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// code to handle click
}
});
}
但是我不為什么我不將數據輸入到ListView中!
問題是您沒有將HashMap
分配給具有要顯示信息的`resultp。
public View getView(final int position, View convertView, ViewGroup parent) {
holder = null;
if (convertView == null) {
convertView = ((Activity) context).getLayoutInflater().inflate(R.layout.listview_item, null);
holder = new ViewHolder(convertView);
holder.rank = (TextView) convertView.findViewById(R.id.rank);
holder.country = (TextView) convertView.findViewById(R.id.country);
holder.population = (TextView) convertView.findViewById(R.id.population);
holder.flag = (ImageView) convertView.findViewById(R.id.flag);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
// Here's the change
resultp = data.get(position);
// Here's the change
holder.rank.setText(resultp.get(MainActivity.RANK));
holder.country.setText(resultp.get(MainActivity.COUNTRY));
holder.population.setText(resultp.get(MainActivity.POPULATION));
imageLoader.DisplayImage(resultp.get(MainActivity.FLAG), holder.flag);
return convertView;
}
要將OnItemClickListener
附加到ListView
,在包含ListView
的Activity
中,添加以下內容:
public class MyActivity implements OnItemClickListener{
ListView lv;
@Override
public void onCreate(Bundle savedInstanceState() {
....
....
// lv initialized here
// adapter of lv set here
attachListeners();
}
private void attachListeners() {
....
....
// attach listeners to other views if you like
lv.setOnItemClickListener(this);
}
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// code to handle click
}
}
或者,如果您不希望Activity
實現OnItemClickListener
,
public class MyActivity {
ListView lv;
@Override
public void onCreate(Bundle savedInstanceState() {
....
....
// lv initialized here
// adapter of lv set here
attachListeners();
}
private void attachListeners() {
....
....
// attach listeners to other views if you like
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// code to handle click
}
});
}
}
首先嘗試解決此問題:
@Override
public Object getItem(int position) {
return data.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
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