我想在我的应用中添加搜索功能。主要是它将json数据检索到List中。
这是我的代码
MainActivity main;
Context context;
LayoutInflater inflater;
ArrayList<HashMap<String, String>> data;
ImageLoader imageLoader;
HashMap<String, String> resultp = new HashMap<String, String>();
private ArrayList<WorldPopulation> arrayList;
public ListViewAdapter(Context context,
ArrayList<HashMap<String, String>> arraylist) {
this.context = context;
data = arraylist;
imageLoader = new ImageLoader(context);
}
public class ViewHolder {
TextView rank;
TextView country;
TextView population;
ImageView flag;
}
@Override
public int getCount() {
return data.size();
}
@Override
public Object getItem(int position) {
return data.get(position);
}
@Override
public long getItemId(int position) {
return 0;
}
public View getView(final int position, View view, ViewGroup parent) {
// Declare Variables
TextView rank;
TextView country;
TextView population;
ImageView flag;
inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View itemView = inflater.inflate(R.layout.listview_item, parent, false);
// Get the position
resultp = data.get(position);
// Locate the TextViews in listview_item.xml
//rank = (TextView) itemView.findViewById(R.id.rank);
country = (TextView) itemView.findViewById(R.id.country);
// population = (TextView) itemView.findViewById(R.id.population);
// Locate the ImageView in listview_item.xml
flag = (ImageView) itemView.findViewById(R.id.flag);
// Capture position and set results to the TextViews
// rank.setText(resultp.get(MainActivity.VIDEO_ID));
country.setText(resultp.get(MainActivity.TITLE));
// population.setText(resultp.get(MainActivity.DESCRIPTION));
// Capture position and set results to the ImageView
// Passes flag images URL into ImageLoader.class
imageLoader.DisplayImage(resultp.get(MainActivity.imgURL), flag);
// Capture ListView item click
mPublisherInterstitialAd = new PublisherInterstitialAd(context);
mPublisherInterstitialAd.setAdUnitId("ca-app-pub-7500090319214897/8263070161");
mPublisherInterstitialAd.setAdListener(new AdListener() {
@Override
public void onAdClosed() {
requestNewInterstitial();
}
});
requestNewInterstitial();
itemView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
// Get the position
resultp = data.get(position);
Intent intent = new Intent(context, PlayerViewDemoActivity.class);
intent.putExtra("videoId", resultp.get(MainActivity.VIDEO_ID));
context.startActivity(intent);
}
});
return itemView;
}
// Filter Class
public void filter(String charText) {
charText = charText.toLowerCase(Locale.getDefault());
data.clear();
if (charText.length() == 0) {
data.addAll((Collection<? extends HashMap<String, String>>) resultp);
} else {
for (HashMap<String, String> wp : (Collection<? extends HashMap<String, String>>) resultp) {
if (wp.get(MainActivity.TITLE).toLowerCase(Locale.getDefault())
.contains(charText)) {
data.add(wp);
}
}
}
notifyDataSetChanged();
}
我在这段代码中遇到了一些错误。我能解决吗？ 我堆叠超过15天。帮助我。
这是我的错误
java.lang.ClassCastException: java.util.HashMap cannot be cast to java.util.Collection
at com.sextech.noui.ListViewAdapter.filter(ListViewAdapter.java:154)
at com.sextech.noui.MainActivity$DownloadJSON$1.afterTextChanged(MainActivity.java:230)
at android.widget.TextView.sendAfterTextChanged(TextView.java:7822)
at android.widget.TextView$ChangeWatcher.afterTextChanged(TextView.java:9635)
at android.text.SpannableStringBuilder.sendAfterTextChanged(SpannableStringBuilder.java:976)
at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:520)
at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:454)
at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:33)
at android.view.inputmethod.BaseInputConnection.replaceText(BaseInputConnection.java:690)
at android.view.inputmethod.BaseInputConnection.setComposingText(BaseInputConnection.java:450)
at com.android.internal.view.IInputConnectionWrapper.executeMessage(IInputConnectionWrapper.java:349)
at com.android.internal.view.IInputConnectionWrapper$MyHandler.handleMessage(IInputConnectionWrapper.java:82)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5593)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
主要活动
// Declare Variables
JSONObject jsonobject;
JSONArray jsonarray;
ListView listview;
ListViewAdapter adapter;
private ProgressBar spinner;
ArrayList<HashMap<String, String>> arraylist;
private AdView mAdView;
private InterstitialAd interstitial;
private long lastPressedTime;
public static String imgURL = "url";
public static String VIDEO_ID = "videoId";
public static String TITLE = "title";
EditText editsearch;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final WifiManager wifiManager = (WifiManager) this.getSystemService(Context.WIFI_SERVICE);
final boolean b=wifiManager.isWifiEnabled();
ConnectivityManager cManager=(ConnectivityManager)getSystemService(this.CONNECTIVITY_SERVICE);
final NetworkInfo nInfo=cManager.getActiveNetworkInfo();
if(nInfo!=null&& nInfo.isConnected()) {
Toast.makeText(this, "You are Connected to the Internet", Toast.LENGTH_LONG).show();
setContentView(R.layout.listview_main);
spinner = (ProgressBar)findViewById(R.id.progressBar1);
new DownloadJSON().execute();
AdView mAdView = new AdView(this);
mAdView.setAdSize(AdSize.SMART_BANNER);
// Gets the ad view defined in layout/ad_fragment.xml with ad unit ID set in
// values/strings.xml.
mAdView = (AdView) findViewById(R.id.ad_view);
// Create an ad request. Check logcat output for the hashed device ID to
// get test ads on a physical device. e.g.
// "Use AdRequest.Builder.addTestDevice("ABCDEF012345") to get test ads on this device."
AdRequest adRequest = new AdRequest.Builder()
.addTestDevice("")
.build();
// Start loading the ad in the background.
mAdView.loadAd(adRequest);
}
else {
new AlertDialog.Builder(this)
.setIcon(android.R.drawable.ic_dialog_alert)
.setTitle("Your DATA Connection is Currently Unreachable")
.setMessage("Connect your WiFi or 2G/3G DATA Connection")
.setPositiveButton("WiFi ", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
try {
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
final Intent mainIntent = new Intent(MainActivity.this, MainActivity.class);
MainActivity.this.startActivity(mainIntent);
MainActivity.this.finish();
}
}, 5000);
wifiManager.setWifiEnabled(true);
Toast.makeText(MainActivity.this, "WiFi Enabling in 5sec Please Wait", Toast.LENGTH_LONG).show();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
})
.setNegativeButton("3G/2G ", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
//use here tablayout to work when 3G/2G connecion is available
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
final Intent mainIntent = new Intent(MainActivity.this, MainActivity.class);
MainActivity.this.startActivity(mainIntent);
MainActivity.this.finish();
}
}, 5000);
Intent myints = new Intent(Settings.ACTION_DATA_ROAMING_SETTINGS);
Toast.makeText(MainActivity.this, "Your DATA Connection is NOW Connected", Toast.LENGTH_LONG).show();
startActivity(myints);
}
})
.setNeutralButton("Exit", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Toast.makeText(MainActivity.this, "To use this Application you have to Connected to the Internet", Toast.LENGTH_LONG).show();
finish();
}
})
.setCancelable(false)
.show();
}
}
public class DownloadJSON extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
spinner.setVisibility(View.VISIBLE);
}
@Override
protected Void doInBackground(Void... params) {
// Create an array
arraylist = new ArrayList<HashMap<String, String>>();
// Retrieve JSON Objects from the given URL address
jsonobject = JSONfunctions.getJSONfromURL("https://www.googleapis.com/youtube/v3/search?part=id%2Csnippet&q=bangla+video+song&maxResults=50&key=AIzaSyAFfA9cCFpmsyK5byKaRWE_oQKjjsABuxI");
try {
// Locate the array name in JSON
JSONArray jsonarray = jsonobject.getJSONArray("items");
for (int i = 0; i < jsonarray.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
jsonobject = jsonarray.getJSONObject(i);
// Retrive JSON Objects
JSONObject jsonObjId = jsonobject.getJSONObject("id");
map.put("videoId", jsonObjId.getString("videoId"));
JSONObject jsonObjSnippet = jsonobject.getJSONObject("snippet");
map.put("title", jsonObjSnippet.getString("title"));
//map.put("description", jsonObjSnippet.getString("description"));
// map.put("flag", jsonobject.getString("flag"));
JSONObject jsonObjThumbnail = jsonObjSnippet.getJSONObject("thumbnails");
String imgURL = jsonObjThumbnail.getJSONObject("high").getString("url");
map.put("url",imgURL);
// Set the JSON Objects into the array
arraylist.add(map);
}
} catch (JSONException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return null;
}
@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
spinner.setVisibility(View.GONE);
editsearch = (EditText) findViewById(R.id.search);
// Capture Text in EditText
editsearch.addTextChangedListener(new TextWatcher() {
@Override
public void afterTextChanged(Editable arg0) {
// TODO Auto-generated method stub
String text = editsearch.getText().toString().toLowerCase(Locale.getDefault());
adapter.filter(text);
}
@Override
public void beforeTextChanged(CharSequence arg0, int arg1,
int arg2, int arg3) {
// TODO Auto-generated method stub
}
@Override
public void onTextChanged(CharSequence arg0, int arg1, int arg2,
int arg3) {
// TODO Auto-generated method stub
}
});
}
}
// Dialouge Box
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
//Handle the back button
if (keyCode == KeyEvent.KEYCODE_BACK) {
//Ask the user if they want to quit
new android.support.v7.app.AlertDialog.Builder (this)
.setIcon(android.R.drawable.ic_dialog_alert)
.setTitle(R.string.quit)
.setMessage(R.string.really_quit)
.setPositiveButton(R.string.yes, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
//Stop the activity
MainActivity.this.finish();
}
})
.setNeutralButton(R.string.neutral, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Toast.makeText(getApplicationContext(), "Rate This App", Toast.LENGTH_SHORT).show();
startActivity(new Intent("android.intent.action.VIEW", Uri.parse("https://play.google.com/store/apps/details?id=com.vdoapps.banglatube")));
}
})
.setNegativeButton(R.string.no, null)
.show();
return true;
} else {
return super.onKeyDown(keyCode, event);
}
}
}
答案 0 :(得分：2)
HashMap未实施Collection。因此，您无法将广告HashMap输入Collection。
在您的情况下，不需要类型转换。 resultp类型的HashMap对象，数据对象的类型为ArrayList<HashMap>，因此您只需执行data.add(resultp)
对于循环，你根本不需要循环。
if (resultp.get(MainActivity.TITLE).toLowerCase(Locale.getDefault()) .contains(charText)) {
data.add(resultp);
}