我正在尝试在自定义列表视图中显示我的数据库，但每次运行该活动时，我的应用程序都会停止运行。请查看我的代码并帮助我。 这是我的活动，我试图从下拉列表中选择的表中提取数据，然后将其显示在自定义列表视图中。
package com.example.aas.advancedattendancesystem;
import android.app.Activity;
import android.app.ListActivity;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Html;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
import model_class.Attendance_database;
import model_class.Attendance_database_handler;
import static com.example.aas.advancedattendancesystem.R.id.dropdown;
import static com.example.aas.advancedattendancesystem.R.id.listshow;
public class Show_databases extends AppCompatActivity {
private Attendance_database_handler adh;
private ArrayList<Attendance_database> dblist = new ArrayList<>();
private CustomArrayAdapter caa;
private ListView lvshow;
private Spinner dropdown;
String[] items = new String[]{"CSE7A"};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getSupportActionBar().setDisplayShowHomeEnabled(true);
getSupportActionBar().setLogo(R.drawable.ic_icon);
getSupportActionBar().setDisplayUseLogoEnabled(true);
getSupportActionBar().setBackgroundDrawable(new ColorDrawable(Color.parseColor("#ffffff")));
getSupportActionBar().setTitle(Html.fromHtml("<font color='#3BB9FF'>Attendance </font>"));
setContentView(R.layout.activity_show_databases);
lvshow=(ListView) findViewById(R.id.listshow);
dropdown=(Spinner) findViewById(R.id.dropdown);
ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, items);
dropdown.setAdapter(adapter);
dropdown.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String selected = parent.getItemAtPosition(position).toString();
refreshData(selected);
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
}
private void refreshData(String selected) {
try {
dblist.clear();
adh = new Attendance_database_handler(getApplicationContext());
ArrayList<Attendance_database> listFromDB;
listFromDB= adh.getAttendance_list(selected);
for (int i = 0; i < listFromDB.size(); i++) {
Integer roll = listFromDB.get(i).getRoll();
String name = listFromDB.get(i).getStudent_name();
Attendance_database mylist = new Attendance_database();
mylist.setRoll(roll);
mylist.setStudent_name(name);
dblist.add(mylist);
}
adh.close();
caa = new CustomArrayAdapter(Show_databases.this, R.layout.custom_listview, dblist);
lvshow.setAdapter(caa);
caa.notifyDataSetChanged();
}catch (Exception e){
Toast.makeText(getApplicationContext(),e.toString(),Toast.LENGTH_LONG).show();
}
}
}
这是我的数据库处理程序
package model_class;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
import static model_class.Constants.ROLL;
import static model_class.Constants.STUDENT_NAME;
import static model_class.Constants.TABLE_NAME;
public class Attendance_database_handler extends SQLiteOpenHelper{
//private final ArrayList<Attendance_database> attendance_list=new ArrayList<>();
public Attendance_database_handler(Context context) {
super(context,Constants.DATABASE_NAME, null, Constants.DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS "+ TABLE_NAME);
Log.v("OnUpgrade","Dropping the table");
onCreate(db);
}
public void addRecord(Attendance_database adb){
SQLiteDatabase db=this.getWritableDatabase();
String CREATE_TABLE="CREATE TABLE IF NOT EXISTS "+
adb.getClass_name()+"("+
ROLL+" INTEGER PRIMARY KEY,"+
STUDENT_NAME+" TEXT);";
db.execSQL(CREATE_TABLE);
ContentValues values=new ContentValues();
values.put(ROLL,adb.getRoll());
values.put(STUDENT_NAME,adb.getStudent_name());
db.insert(adb.getClass_name(),null,values);
db.close();
}
public ArrayList<Attendance_database> getAttendance_list(String selected) {
//attendance_list.clear();
String selectQuery = "SELECT * FROM " + selected;
SQLiteDatabase db = this.getReadableDatabase();
// Cursor cursor = db.rawQuery(selectQuery, null);
Cursor cursor = db.rawQuery(selectQuery,null);
ArrayList<Attendance_database> attendance_list = new ArrayList<>();
//loop through cursor
if (cursor.moveToFirst()) {
do {
Attendance_database myList = new Attendance_database();
myList.setRoll(cursor.getInt(cursor.getColumnIndex(ROLL)));
myList.setStudent_name(cursor.getString(cursor.getColumnIndex(STUDENT_NAME)));
attendance_list.add(myList);
} while (cursor.moveToNext());
}
cursor.close();
db.close();
return attendance_list;
}
}
这是一个具有我想要的所有参数的类。
package model_class;
public class Constants {
public static final String DATABASE_NAME="db_name";
public static final int DATABASE_VERSION=8;
public static final String TABLE_NAME="tb_name";
public static final String STUDENT_NAME="st_name";
public static final String ROLL="st_roll";
}
这是我的自定义数组适配器
package com.example.aas.advancedattendancesystem;
import android.app.Activity;
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListAdapter;
import android.widget.TextView;
import java.util.ArrayList;
import model_class.Attendance_database;
public class CustomArrayAdapter extends ArrayAdapter<Attendance_database> {
private ArrayList<Attendance_database> alist = new ArrayList<>();
Activity activity;
int layoutResource;
Attendance_database adb;
public CustomArrayAdapter(Activity act, int resource, ArrayList<Attendance_database> data) {
super(act, resource, data);
activity = act;
layoutResource = resource;
alist = data;
notifyDataSetChanged();
}
@Override
public int getCount() {
return alist.size();
}
@Override
public Attendance_database getItem(int position) {
return alist.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = convertView;
ViewHolder holder;
if (view == null || (view.getTag())==null) {
LayoutInflater inflater;
inflater = LayoutInflater.from(activity);
view = inflater.inflate(layoutResource, null);
holder=new ViewHolder();
holder.roll= (TextView)view.findViewById(R.id.tvroll);
holder.name= (TextView) view.findViewById(R.id.tvname);
view.setTag(holder);
}else{
holder=(ViewHolder) view.getTag();
}
holder.mylist=getItem(position);
holder.roll.setText(holder.mylist.getRoll());
holder.name.setText(holder.mylist.getStudent_name());
return view;
}
class ViewHolder{
Attendance_database mylist;
TextView roll;
TextView name;
}}
请帮忙。我无法弄清楚出了什么问题。提前谢谢你：）
logcat的：
07-12 17:09:49.168 8600-8600/com.example.aas.advancedattendancesystem
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.aas.advancedattendancesystem, PID: 8600
android.content.res.Resources$NotFoundException: String resource ID #0x1
at android.content.res.Resources.getText(Resources.java:331)
at android.widget.TextView.setText(TextView.java:4554)
at com.example.aas.advancedattendancesystem.CustomArrayAdapter.getView(CustomArrayAdapter.java:74)
at android.widget.AbsListView.obtainView(AbsListView.java:2362)
at android.widget.ListView.makeAndAddView(ListView.java:1970)
at android.widget.ListView.fillDown(ListView.java:704)
at android.widget.ListView.fillFromTop(ListView.java:765)
at android.widget.ListView.layoutChildren(ListView.java:1716)
at android.widget.AbsListView.onLayout(AbsListView.java:2161)
at android.view.View.layout(View.java:17523)
at android.view.ViewGroup.layout(ViewGroup.java:5612)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
at android.view.View.layout(View.java:17523)
at android.view.ViewGroup.layout(ViewGroup.java:5612)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:17523)
at android.view.ViewGroup.layout(ViewGroup.java:5612)
at android.support.v7.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:437)
at android.view.View.layout(View.java:17523)
at android.view.ViewGroup.layout(ViewGroup.java:5612)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:17523)
at android.view.ViewGroup.layout(ViewGroup.java:5612)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
at android.view.View.layout(View.java:17523)
at android.view.ViewGroup.layout(ViewGroup.java:5612)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at com.android.internal.policy.DecorView.onLayout(DecorView.java:724)
at android.view.View.layout(View.java:17523)
at android.view.ViewGroup.layout(ViewGroup.java:5612)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2342)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2069)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1246)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6301)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:871)
at android.view.Choreographer.doCallbacks(Choreographer.java:683)
at android.view.Choreographer.doFrame(Choreographer.java:619)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:857)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
我认为错误发生在customArrayAdapter中，但我无法弄明白确切的位置