CreateDatabse：
public void createDataBase() throws IOException
{
//If database not exists copy it from the assets
boolean mDataBaseExist = checkDataBase();
if(!mDataBaseExist)
{
this.getReadableDatabase();
this.close();
try
{
//Copy the database from assests
copyDataBase();
}
catch (IOException mIOException)
{
throw new Error("ErrorCopyingDataBase");
}
}
}
TestAdapter：
import java.io.IOException;
import java.util.ArrayList;
import android.view.View;
import android.view.ViewGroup;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
public class TestAdapter extends Activity
{
ArrayList<Horario> array = new ArrayList<Horario>();
protected static final String TAG = "DataAdapter";
private final Context mContext;
private SQLiteDatabase mDb;
private DataBaseHelper mDbHelper;
public TestAdapter(Context context)
{
this.mContext = context;
mDbHelper = new DataBaseHelper(mContext);
}
public TestAdapter createDatabase() throws SQLException
{
try
{
mDbHelper.createDataBase();
}
catch (IOException mIOException)
{
Log.e(TAG, mIOException.toString() + " UnableToCreateDatabase");
throw new Error("UnableToCreateDatabase");
}
return this;
}
public TestAdapter open() throws SQLException
{
try
{
mDbHelper.openDataBase();
mDbHelper.close();
mDb = mDbHelper.getReadableDatabase();
}
catch (SQLException mSQLException)
{
Log.e(TAG, "open >>"+ mSQLException.toString());
throw mSQLException;
}
return this;
}
public void close()
{
mDbHelper.close();
}
public Cursor getTestData()
{
try
{
String sql ="SELECT * FROM horarios";
Cursor mCur = mDb.rawQuery(sql, null);
if (mCur!=null)
{
mCur.moveToNext();
}
return mCur;
}
catch (SQLException mSQLException)
{
Log.e(TAG, "getTestData >>"+ mSQLException.toString());
throw mSQLException;
}
}
public ArrayList<Horario> getorigem(){
String query = "select origem, destino From horarios";
Cursor cursor = mDb.rawQuery(query, new String[]{});
ArrayList<Horario> array = new ArrayList<Horario>();
while (cursor.moveToNext()) {
String _origem = cursor.getString(cursor.getColumnIndex("origem"));
String _destino = cursor.getString(cursor.getColumnIndex("destino"));
array.add(new Horario(_origem, _destino));
}
return array;
}
public void populateListView() {
// TODO Auto-generated method stub
MyListAdapter adapter = new MyListAdapter();
ListView list = (ListView) findViewById(R.id.list_view);
list.setAdapter(adapter);
}
private class MyListAdapter extends ArrayAdapter<Horario>{
public MyListAdapter() {
super(TestAdapter.this, R.layout.item_view, array);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
//Make sure we have view to work with
View itemView = convertView;
if(itemView == null){
itemView = getLayoutInflater().inflate(R.layout.item_view, parent, false);
}
//Find the car to work with.
Horario currentHorario = array.get(position);
//Fill the view
// Origem:
TextView makeText = (TextView) itemView.findViewById(R.id.view_origem);
makeText.setText(currentHorario.getOrigem());
// Destino:
TextView ConditionText = (TextView) itemView.findViewById(R.id.view_destino);
ConditionText.setText(currentHorario.getDestino());
return itemView;
}
}
}
我尝试填充像这样的ListView：
public void populateListView() {
// TODO Auto-generated method stub
ArrayAdapter<Horario> adapter = new MyListAdapter();
ListView list = (ListView) findViewById(R.id.list_view);
list.setAdapter(adapter);
}
private class MyListAdapter extends ArrayAdapter<Horario>{
public MyListAdapter() {
super(TestAdapter.this, R.layout.item_view, array);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View itemView = convertView;
if(itemView == null){
itemView = getLayoutInflater().inflate(R.layout.item_view, parent, false);
}
Horario currentHorario = array.get(position);
//Fill the view
// Origem:
TextView makeText = (TextView) itemView.findViewById(R.id.view_origem);
makeText.setText(currentTime.getOrigem());
// Destino:
TextView makeText = (TextView) itemView.findViewById(R.id.view_destino);
makeText.setText(currentTime.getDestino());
return itemView;
}
}
主要活动：
import android.os.Bundle;
import android.app.Activity;
import android.database.sqlite.SQLiteDatabase;
import android.view.View;
public class MainActivity extends Activity {
SQLiteDatabase mDb;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TestAdapter mDbHelper = new TestAdapter(getBaseContext());
mDbHelper.createDatabase();
}
public void search(View v) {
setContentView(R.layout.list_view);
TestAdapter mDbHelper = new TestAdapter(getBaseContext());
mDbHelper.open();
mDbHelper.getorigem();
mDbHelper.populateListView();
mDbHelper.close();
}
}
但是当我点击按钮时它会出错并关闭 logcat的
02-24 08:29:32.290: E/AndroidRuntime(1168): FATAL EXCEPTION: main
02-24 08:29:32.290: E/AndroidRuntime(1168): Process: arr.app, PID: 1168
02-24 08:29:32.290: E/AndroidRuntime(1168): java.lang.IllegalStateException: Could not execute method of the activity
02-24 08:29:32.290: E/AndroidRuntime(1168): at android.view.View$1.onClick(View.java:3823)
02-24 08:29:32.290: E/AndroidRuntime(1168): at android.view.View.performClick(View.java:4438)
02-24 08:29:32.290: E/AndroidRuntime(1168): at android.view.View$PerformClick.run(View.java:18422)
02-24 08:29:32.290: E/AndroidRuntime(1168): at android.os.Handler.handleCallback(Handler.java:733)
02-24 08:29:32.290: E/AndroidRuntime(1168): at android.os.Handler.dispatchMessage(Handler.java:95)
02-24 08:29:32.290: E/AndroidRuntime(1168): at android.os.Looper.loop(Looper.java:136)
02-24 08:29:32.290: E/AndroidRuntime(1168): at android.app.ActivityThread.main(ActivityThread.java:5017)
02-24 08:29:32.290: E/AndroidRuntime(1168): at java.lang.reflect.Method.invokeNative(Native Method)
02-24 08:29:32.290: E/AndroidRuntime(1168): at java.lang.reflect.Method.invoke(Method.java:515)
02-24 08:29:32.290: E/AndroidRuntime(1168): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
02-24 08:29:32.290: E/AndroidRuntime(1168): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
02-24 08:29:32.290: E/AndroidRuntime(1168): at dalvik.system.NativeStart.main(Native Method)
02-24 08:29:32.290: E/AndroidRuntime(1168): Caused by: java.lang.reflect.InvocationTargetException
02-24 08:29:32.290: E/AndroidRuntime(1168): at java.lang.reflect.Method.invokeNative(Native Method)
02-24 08:29:32.290: E/AndroidRuntime(1168): at java.lang.reflect.Method.invoke(Method.java:515)
02-24 08:29:32.290: E/AndroidRuntime(1168): at android.view.View$1.onClick(View.java:3818)
02-24 08:29:32.290: E/AndroidRuntime(1168): ... 11 more
02-24 08:29:32.290: E/AndroidRuntime(1168): Caused by: java.lang.IllegalStateException: System services not available to Activities before onCreate()
02-24 08:29:32.290: E/AndroidRuntime(1168): at android.app.Activity.getSystemService(Activity.java:4532)
02-24 08:29:32.290: E/AndroidRuntime(1168): at android.widget.ArrayAdapter.init(ArrayAdapter.java:310)
02-24 08:29:32.290: E/AndroidRuntime(1168): at android.widget.ArrayAdapter.<init>(ArrayAdapter.java:153)
02-24 08:29:32.290: E/AndroidRuntime(1168): at arr.app.TestAdapter$MyListAdapter.<init>(TestAdapter.java:119)
02-24 08:29:32.290: E/AndroidRuntime(1168): at arr.app.TestAdapter.populateListView(TestAdapter.java:111)
02-24 08:29:32.290: E/AndroidRuntime(1168): at arr.app.MainActivity.search(MainActivity.java:32)
02-24 08:29:32.290: E/AndroidRuntime(1168): ... 14 more
activity_main.xml中
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<Button
android:id="@+id/btnsearch"
android:layout_width="150dp"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:onClick="search"
android:text="Search" />
<TextView
android:id="@+id/lbldestino"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/lblorigem"
android:layout_below="@+id/lblorigem"
android:layout_marginTop="54dp"
android:text="Destino"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/lblorigem"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginTop="18dp"
android:text="Origem"
android:textAppearance="?android:attr/textAppearanceMedium" />
<EditText
android:id="@+id/txtorigem"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/lblorigem"
android:layout_below="@+id/lblorigem"
android:ems="10" >
<requestFocus />
</EditText>
<EditText
android:id="@+id/txtdestino"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/lbldestino"
android:layout_below="@+id/lbldestino"
android:ems="10" />
</RelativeLayout>
我开始编程到android大约1周，我在某些天试图解决这个问题 感谢任何帮助
答案 0 :(得分：0)
问题是您的适配器正在扩展Activity而未在setContentView方法中实现onCreate，因此在调用findViewById(R.id.list_view);时失败。假设populateListView布局文件（R.layout.list_view）包含名为MainActivity的{{1}}，您需要在list_view内使用ListView方法的内容（R.id.list_view）。
list_view在public void search(View v) {
setContentView(R.layout.list_view);
TestAdapter mDbHelper = new TestAdapter(getBaseContext());
mDbHelper.open();
ArrayAdapter<Horario> adapter = new MyListAdapter(mDbHelper.getorigem());
ListView list = (ListView) findViewById(R.id.list_view);
list.setAdapter(adapter);
mDbHelper.close();
}
修改构造函数：
MyListAdapter要在单击按钮上调用搜索，请使用以下方法：
public MyListAdapter(ArrayList<Horario> arrayHorario) {
array = arrayHorario;
super(TestAdapter.this, R.layout.item_view, array);
}
希望它有所帮助！