列表视图lazyadapter [英] listview lazyadapter
本文介绍了列表视图lazyadapter的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我喜欢从ListView控件传递所选项目的值另一项活动。
我用这code来获得与HashMap的相关细节，但我得到的 java.lang.Integer中不能转换到的java.util.HashMap 。
公共无效onItemClick（适配器视图＆LT;＆GT;母公司，观景，
INT位置，长的id）{
HashMap的＆LT;字符串，字符串＆GT; O =（HashMap的＆LT;字符串，字符串＆GT;）list.getItemAtPosition（位置）;
Toast.makeText（CustomizedListView.this，ID+ o.get（KEY_TITLE）+'被单击。，Toast.LENGTH_SHORT）.show（）; }
我如何解决它。我真的AP preciate的帮助。
先谢谢了。
公共类CustomizedListView延伸活动{
//所有静态变量
静态最终字符串URL =https://itunes.apple.com/us/rss/topalbums/limit=20/json;
// XML节点键
静态最后弦乐KEY_SONG =歌; //父节点
静态最后弦乐KEY_ID =ID;
静态最后弦乐KEY_TITLE =称号;
静态最后弦乐KEY_ARTIST =艺术家;
静态最后弦乐KEY_DURATION =时间;
静态最后弦乐KEY_THUMB_URL =thumb_url; ListView控件列表;
LazyAdapter适配器; @覆盖
公共无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.main）;
ArrayList的＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT; songsList =新的ArrayList＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT;（）; JSONObject的JSON = JSONfunctions.getJSONfromURL（URL）;
尝试{
JSONObject的ARR2 = json.getJSONObject（饲料）;
JSONArray ARR = arr2.getJSONArray（项）; 的for（int i = 0; I＆LT; arr.length（）;我++）{
的JSONObject E1 = arr.getJSONObject（ⅰ）; JSONArray ARR3 = e1.getJSONArray（IM：图像）; JSONObject的arr8 = e1.getJSONObject（IM：名称）; JSONObject的arr10 = e1.getJSONObject（IM：艺术家）; 的JSONObject E12 = arr3.getJSONObject（0）; //创建新的HashMap
HashMap的＆LT;字符串，字符串＆GT;地图=新的HashMap＆LT;字符串，字符串＆GT;（）; map.put（KEY_THUMB_URL，e12.getString（标签））; map.put（KEY_ARTIST，arr8.getString（标签））;
map.put（KEY_TITLE，arr10.getString（标签））;
//添加HashList到ArrayList的
songsList.add（地图）;
} }赶上（JSONException E）{
// Log.e（log_tag，错误分析数据+ e.toString（））;
Toast.makeText（getBaseContext（），
网络通信错误！，5）.show（）;
}
名单=（ListView控件）findViewById（R.id.list）; //通过传递XML数据的ArrayList获取适配器
适配器=新LazyAdapter（这一点，songsList）;
list.setAdapter（适配器）; // Click事件的单排列表
list.setOnItemClickListener（新OnItemClickListener（）{ @燮pressWarnings（未登记）
@覆盖
公共无效onItemClick（适配器视图＆LT;＆GT;母公司，观景，
INT位置，长的id）{
HashMap的＆LT;字符串，字符串＆GT; O =（HashMap的＆LT;字符串，字符串＆GT;）list.getItemAtPosition（位置）;
Toast.makeText（CustomizedListView.this，ID+ o.get（KEY_TITLE）+'被单击。，Toast.LENGTH_SHORT）.show（）; }
}）;
}
}
但同样code节的工作原理：为什么？
这是一个 SimpleAdapter 在这种情况下。
公共类主要扩展ListActivity {
/ **当第一次创建活动调用。 * /
@覆盖
公共无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.listplaceholder）; ArrayList的＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT; MYLIST =新的ArrayList＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT;（）;
JSON的JSONObject = JSONfunctions.getJSONfromURL(\"http://api.geonames.org/earthquakesJSON?north=44.1&south=-9.9&east=-22.4&west=55.2&username=demo\"); 尝试{ JSONArray地震= json.getJSONArray（地震）; 的for（int i = 0; I＆LT; earthquakes.length（）;我++）{
HashMap的＆LT;字符串，字符串＆GT;地图=新的HashMap＆LT;字符串，字符串＆GT;（）;
JSONObject的E = earthquakes.getJSONObject（I） map.put（ID，将String.valueOf（i）段）;
map.put（名，地震的名字：+ e.getString（eqid））;
map.put（大小，震级：+ e.getString（大小））;
mylist.add（地图）;
}
}赶上（JSONException E）{
Log.e（log_tag，错误分析数据+ e.toString（））;
} ListAdapter适配器=新SimpleAdapter（这一点，MYLIST，R.layout.main，
新的String [] {名，大小}，
新的INT [] {R.id.item_title，R.id.item_subtitle}）; setListAdapter（适配器）; 最终的ListView LV = getListView（）;
lv.setTextFilterEnabled（真）;
lv.setOnItemClickListener（新OnItemClickListener（）{
公共无效onItemClick（适配器视图＆LT;＆GT;母公司，观景，INT位置，长的id）{
@燮pressWarnings（未登记）
HashMap的＆LT;字符串，字符串＆GT; O =（HashMap的＆LT;字符串，字符串＆GT;）lv.getItemAtPosition（位置）;
Toast.makeText（Main.this，ID+ o.get（ID）+'被点击了。Toast.LENGTH_SHORT）.show（）; }
}）;
}
}
解决方案
尝试更换
的HashMap＆LT;字符串，字符串＆GT; O =（HashMap的＆LT;字符串，字符串＆GT;）list.getItemAtPosition（位置）;
与
INT O =（int）的list.getItemAtPosition（位置）;
看来你的列表视图项包含 INT 键入值
I like to pass selected item value from ListView to another activity.
I am using this code to get the details associated with the hashmap but I get java.lang.Integer cannot be cast to java.util.HashMap .
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
HashMap<String, String> o = (HashMap<String, String>) list.getItemAtPosition(position);
Toast.makeText(CustomizedListView.this, "ID '" + o.get("KEY_TITLE") + "' was clicked.", Toast.LENGTH_SHORT).show();
}
How do I fix it.I really appreciate the help.
Thanks in Advance.
public class CustomizedListView extends Activity {
// All static variables
static final String URL = "https://itunes.apple.com/us/rss/topalbums/limit=20/json";
// XML node keys
static final String KEY_SONG = "song"; // parent node
static final String KEY_ID = "id";
static final String KEY_TITLE = "title";
static final String KEY_ARTIST = "artist";
static final String KEY_DURATION = "duration";
static final String KEY_THUMB_URL = "thumb_url";
ListView list;
LazyAdapter adapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
JSONObject json = JSONfunctions.getJSONfromURL(URL);
try {
JSONObject arr2 = json.getJSONObject("feed");
JSONArray arr = arr2.getJSONArray("entry");
for (int i = 0; i < arr.length(); i++) {
JSONObject e1 = arr.getJSONObject(i);
JSONArray arr3 = e1.getJSONArray("im:image");
JSONObject arr8 = e1.getJSONObject("im:name");
JSONObject arr10 = e1.getJSONObject("im:artist");
JSONObject e12 = arr3.getJSONObject(0);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
map.put(KEY_THUMB_URL, e12.getString("label"));
map.put(KEY_ARTIST, arr8.getString("label"));
map.put(KEY_TITLE, arr10.getString("label"));
// adding HashList to ArrayList
songsList.add(map);
}
} catch (JSONException e) {
// Log.e("log_tag", "Error parsing data "+e.toString());
Toast.makeText(getBaseContext(),
"Network communication error!", 5).show();
}
list=(ListView)findViewById(R.id.list);
// Getting adapter by passing xml data ArrayList
adapter=new LazyAdapter(this, songsList);
list.setAdapter(adapter);
// Click event for single list row
list.setOnItemClickListener(new OnItemClickListener() {
@SuppressWarnings("unchecked")
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
HashMap<String, String> o = (HashMap<String, String>) list.getItemAtPosition(position);
Toast.makeText(CustomizedListView.this, "ID '" + o.get("KEY_TITLE") + "' was clicked.", Toast.LENGTH_SHORT).show();
}
});
}
}
BUT the same code BELOW works : WHY ?
It is a SimpleAdapter in this case.
public class Main extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listplaceholder);
ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
JSONObject json = JSONfunctions.getJSONfromURL("http://api.geonames.org/earthquakesJSON?north=44.1&south=-9.9&east=-22.4&west=55.2&username=demo");
try{
JSONArray earthquakes = json.getJSONArray("earthquakes");
for(int i=0;i<earthquakes.length();i++){
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = earthquakes.getJSONObject(i);
map.put("id", String.valueOf(i));
map.put("name", "Earthquake name:" + e.getString("eqid"));
map.put("magnitude", "Magnitude: " + e.getString("magnitude"));
mylist.add(map);
}
}catch(JSONException e) {
Log.e("log_tag", "Error parsing data "+e.toString());
}
ListAdapter adapter = new SimpleAdapter(this, mylist , R.layout.main,
new String[] { "name", "magnitude" },
new int[] { R.id.item_title, R.id.item_subtitle });
setListAdapter(adapter);
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
@SuppressWarnings("unchecked")
HashMap<String, String> o = (HashMap<String, String>) lv.getItemAtPosition(position);
Toast.makeText(Main.this, "ID '" + o.get("id") + "' was clicked.", Toast.LENGTH_SHORT).show();
}
});
}
}
解决方案
try to replace
HashMap<String, String> o = (HashMap<String, String>) list.getItemAtPosition(position);
with
int o = (int) list.getItemAtPosition(position);
it seems your listview items contains the int type values
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