如何修复Android中的java.lang.ClassCastException [英] How to fix java.lang.ClassCastException Android
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问题描述
我正在搜索这种情况，但在C#中找到了.好的，我尝试使用ListFragment android，json和mysql将数据显示到listview中，但是运行它时出现Class Cast错误，我希望有人能帮助我. 这是我的错误:
I have searching for this case, i found it but in C#. Oke, I try to show my data into the listview using ListFragment android, json and mysql, but i got an error Class Cast when I running it, i hope anyone can help me. Here My Error :
06-12 17:04:04.685 20975-20975/com.spp.udi.sppmap E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.spp.udi.sppmap, PID: 20975
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.spp.udi.sppmap/com.spp.udi.sppmap.Potensi}: java.lang.ClassCastException: com.spp.udi.sppmap.Potensi cannot be cast to android.app.Activity
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2345)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2494)
at android.app.ActivityThread.access$900(ActivityThread.java:153)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1347)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5451)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.ClassCastException: com.spp.udi.sppmap.Potensi cannot be cast to android.app.Activity
at android.app.Instrumentation.newActivity(Instrumentation.java:1068)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2335)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2494)
at android.app.ActivityThread.access$900(ActivityThread.java:153)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1347)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5451)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
我的Potensi.java:
My Potensi.java :
package com.spp.udi.sppmap;
import android.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import android.app.ListFragment;
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.util.Log;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class Potensi extends ListFragment {
private static final String ID_KECAMATAN = "id_kecamatan";
private static final String NAMA_KECAMATAN = "nama_kecamatan";
ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String,String>>();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
JSONObject json = JSONFunction.getJSONFromUrl("http://192.168.43.203/project/s9/udi/android/potensi.php");
try {
JSONArray laporan = json.getJSONArray("result");
for(int i=0; i<laporan.length(); i++){
JSONObject jsonobj = laporan.getJSONObject(i);
String id_kecamatan = jsonobj.getString(ID_KECAMATAN);
String nama_kecamatan = jsonobj.getString(NAMA_KECAMATAN);
HashMap<String, String> map = new HashMap<String, String>();
map.put("id_kecamatan", id_kecamatan);
map.put("nama_kecamatan", nama_kecamatan);
mylist.add(map);
}
} catch (JSONException e) {
Log.e("log_tag","error parsing data "+e.toString());
}
this.adapter_listview();
}
public void adapter_listview() {
ListAdapter adapter = new SimpleAdapter(getActivity(), mylist, R.layout.potensi,
new String[] {ID_KECAMATAN, NAMA_KECAMATAN}, new int[] {R.id.id_kecamatan, R.id.nama_kecamatan});
setListAdapter(adapter);
ListView lv = getListView();
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,int position, long id) {
String id_kecamatan = ((TextView) view.findViewById(R.id.id_kecamatan)).getText().toString();
Intent in = new Intent(getActivity(), DetailPotensi.class);
in.putExtra(ID_KECAMATAN, id_kecamatan);
startActivity(in);
}
});
}
}
我的输出json:
{"result":[{"id_kecamatan":"8","nama_kecamatan":"Batang Dua"},{"id_kecamatan":"7","nama_kecamatan":"Pulau Moti"},{"id_kecamatan":"6","nama_kecamatan":"Pulau Hiri"},{"id_kecamatan":"5","nama_kecamatan":"Pulau Ternate"},{"id_kecamatan":"4","nama_kecamatan":"Ternate Utara"},{"id_kecamatan":"3","nama_kecamatan":"Ternate Tengah"},{"id_kecamatan":"2","nama_kecamatan":"Ternate Selatan"}]}
推荐答案
ClassCastException
抛出该错误以表明代码已尝试将对象强制转换为 不是实例的子类.
Thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance.
Caused by: java.lang.ClassCastException: com.spp.udi.sppmap.Potensi cannot be cast to android.app.Activity
您正在使用 android inbuild Listview @ + id/android:list
因此，请扩展ListActivity 而不是 ListFragment .
public class Potensi extends ListActivity{
这篇关于如何修复Android中的java.lang.ClassCastException的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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