如何在ListView onItemClick 中获取HashMap id 值? [英] How to get HashMap id value in ListView onItemClick?
问题描述
我尝试将 ImageList 添加到我的应用程序中.我添加成功了.它显示了我被选中的银行的标志.我通过 HashMap 添加了这一点，因为我想在单击日志图像时取银行名称.
I tried to add ImageList to my application. i added it successfully. It shows Logos of banks which i was selected. I added that through HashMap, because i want to take bank name when click the log image.
但是我无法在 onItemClick 方法中获取银行名称.谁能帮我解决这个问题?
But i can't get the bank name in onItemClick method. Can anyone help me to fix this problem?
这是我的活动代码.
public void getImageData() {
map = new HashMap<String, String>();
try {
JSONObject jsonResponse = new JSONObject(strJson1);
JSONArray jsonMainNode = jsonResponse.optJSONArray("bank");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
img_url = jsonChildNode.optString("logo");
String test1 = img_test_url + img_url;
bName = jsonChildNode.optString("name");
map.put(bName, test1);
}
ItemsAdapter adapter = new ItemsAdapter(getApplicationContext(),map);
list.setAdapter(adapter);
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Connection Error...",
Toast.LENGTH_LONG).show();
}
list.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
HashMap<String, String> obj = (HashMap<String, String>) adapter.getItem(arg2);
String name = (String) obj.get("bName");
Log.d("Bank Name", name);
}
});
}
这是我的适配器类
public class ItemsAdapter extends BaseAdapter {
private final Context context;
ImageView imageView;
private String[] mKeys;
HashMap<String, String> map;
ItemsAdapter(Context context, HashMap<String, String> map) {
this.context = context;
this.map = map;
mKeys = map.keySet().toArray(new String[map.size()]);
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return map.size();
}
@Override
public Object getItem(int position) {
return map.get(mKeys[position]);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
String key = mKeys[position];
String Value = getItem(position).toString();
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = convertView;
if (null == convertView)
rowView = inflater.inflate(R.layout.items, parent, false);
imageView = (ImageView) rowView.findViewById(R.id.imageView1);
Bitmap bitmap;
URL imageURL = null;
Log.d("value", Value);
Log.d("key", key);
try {
imageURL = new URL(Value);
}
catch (MalformedURLException e) {
e.printStackTrace();
}
try {
HttpURLConnection connection = (HttpURLConnection) imageURL.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream inputStream = connection.getInputStream();
bitmap = BitmapFactory.decodeStream(inputStream);// Convert to bitmap
imageView.setImageBitmap(bitmap);
} catch (IOException e) {
e.printStackTrace();
}
return rowView ;
}
}
这是 LogCat 错误.
This is LogCat error.
03-17 13:58:13.620: E/AndroidRuntime(10172): FATAL EXCEPTION: main
03-17 13:58:13.620: E/AndroidRuntime(10172): java.lang.NullPointerException
03-17 13:58:13.620: E/AndroidRuntime(10172): at com.example.testhashimage.MainActivity$1.onItemClick(MainActivity.java:161)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.widget.AdapterView.performItemClick(AdapterView.java:301)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.widget.AbsListView.performItemClick(AbsListView.java:1280)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.widget.AbsListView$PerformClick.run(AbsListView.java:3071)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.widget.AbsListView$1.run(AbsListView.java:3973)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.os.Handler.handleCallback(Handler.java:615)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.os.Handler.dispatchMessage(Handler.java:92)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.os.Looper.loop(Looper.java:137)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.app.ActivityThread.main(ActivityThread.java:4960)
03-17 13:58:13.620: E/AndroidRuntime(10172): at java.lang.reflect.Method.invokeNative(Native Method)
03-17 13:58:13.620: E/AndroidRuntime(10172): at java.lang.reflect.Method.invoke(Method.java:511)
03-17 13:58:13.620: E/AndroidRuntime(10172): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
03-17 13:58:13.620: E/AndroidRuntime(10172): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
03-17 13:58:13.620: E/AndroidRuntime(10172): at dalvik.system.NativeStart.main(Native Method)
推荐答案
您有两个错误.首先，您试图访问未初始化的成员类，因为您正在隐藏成员的类范围，并使用本地范围重新声明变量.这很容易修复.你可以使用
You have two errors. First you are trying to access a member class that is not intialized, since you are hding the member's class scoping redeclaring the variable with local scope. This is easily fixable. You can use
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
onItemClick 的第一个参数，用于检索位置处的元素.在你的情况下是:
the firs argument of onItemClick to retrieve the element at position. In your case it is:
arg0.getItemAtPosition(arg2)
第二个错误是您将String 转换为HashMap.您的 getItem 返回:
the second error is that you are casting a String to HashMap. Your getItem returns:
map.get(mKeys[position]);
并且由于您在自定义适配器中声明了 HashMap，getItem 实际上是返回一个 String 实例.所以你有错误的演员.一旦你修复了 NPE，你就会得到一个 ClassCastException
and since you declared HashMap<String, String> in your custom adapter, getItem is actually return a String instance. So you have the wrong cast. As soon as you fix the NPE you will get a ClassCastException
要实现你想要的，你应该改变
to achieve what you want you should change from
- 将表单 HashMap 切换为另一种基于索引、基于顺序的集合.例如，它可以是
ArrayList，或者您可以创建自己的javabean.我将假设您将使用Pair类，将 id 作为第一个元素，将 url 作为第二个值 相应地更改
getView和getItem.你可以摆脱
- Switch form HashMap to another kind, index, order based collection. It could be, for instance an
ArrayList<Pair<String, String>>, or you can create your ownjavabean. I will assume that you are going to use thePairclass, with the id as first element, and the url as second value Change
getViewandgetItemaccordingly. You can get rid
String key = mKeys[position];
String Value = getItem(position).toString();
您的 getItem 将如下所示:
your getItem will look like:
@Override
public Object getItem(int position) {
return dataset.get(position);
}
和 getView 将以
and getView will start with
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Pair<String, String> item = (Pair<String, String>)getItem(position);
String Value = item.second;
}
在 onItemClick 里面你会得到类似的东西:
inside onItemClick you'll get a similar thing:
list.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
Pair<String, String> item = (Pair<String, String>)arg0.getItemAtPosition(arg2);
String id = item.first;
}
正如@Raghunandan 正确指出的那样，您应该将所有与网络/阻塞相关的操作放到不同的线程中.最简单的方法，android 友好，是使用 AsyncTask.您可以阅读本指南.
as correctly pointed out by @Raghunandan, you should all the Network/Blocking related operations into a different thread. The mostly easy way, android friendly, is to use an AsyncTask. You can read this guide.
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