我尝试了一个带有listview的android项目。我使用hashmap在DB中添加了值，并在listview中显示结果。但我无法正确启动..请帮我解决这个问题......
这是我的java代码
package com.example.subitemlistviewdb;
import java.util.ArrayList;
import java.util.HashMap;
import android.R;
import android.os.Bundle;
import android.app.Activity;
import android.app.ListActivity;
import android.view.Menu;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
public class MainActivity extends ListActivity {
DBController dbc=new DBController(this);
ListView l;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_item);
l=(ListView) findViewById(R.id.list);
ArrayList<HashMap<String, String>> countrylist=dbc.getinfo();
if(countrylist.size()!=0)
{
l=getListView();
ListAdapter adapter=new SimpleAdapter(MainActivity.this, countrylist, R.layout.list_content, new String [] {"id","cname","capital"}, new int [] {R.id.title,R.id.text1,R.id.text2});
setListAdapter(adapter);
}
}
}
我使用插入查询添加了数据。所以我想在列表视图中显示结果。 这是我的DB类
package com.example.subitemlistviewdb;
import java.util.ArrayList;
import java.util.HashMap;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DBController extends SQLiteOpenHelper {
private static final String LOGCAT="null";
public DBController(Context con)
{
super(con,"sqlite.db",null,1);
Log.d(LOGCAT, "CREATED");
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL("CREATE TABLE country (id INTEGER PRIMARY KEY AUTOINCREMENT, cname TEXT, capital TEXT)");
db.execSQL("INSERT INTO country (id,'cname','capital') Values (1,'INDIA', Delhi)");
db.execSQL("INSERT INTO country (id,'cname','capital') Values (2,'CHINA', Beijing)");
db.execSQL("INSERT INTO country (id,'cname','capital') Values (3,'ENGLAND', London)");
db.execSQL("INSERT INTO country (id,'cname','capital') Values (4,'USA', Washington)");
db.execSQL("INSERT INTO country (id,'cname','capital') Values (5,'SRI LANKA', Columbo)");
db.execSQL("INSERT INTO country (id,'cname','capital') Values (6,'AFGHANISTHAN', Kaabul)");
}
public void onUpgrade(SQLiteDatabase db,int version_old,int version_new){
db.execSQL("DROP TABLE IT EXISTS country");
onCreate(db);
}
public ArrayList<HashMap<String, String>> getinfo(){
ArrayList<HashMap<String, String>> clist;
clist=new ArrayList<HashMap<String,String>>();
String query="SELECT * FROM country";
SQLiteDatabase db=this.getWritableDatabase();
Cursor c=db.rawQuery(query,null);
if(c.moveToFirst())
{
do
{
HashMap<String, String> map=new HashMap<String, String>();
map.put("id", c.getString(0));
map.put("cname", c.getString(1));
map.put("capital", c.getString(2));
clist.add(map);
}while(c.moveToNext());
}
return clist;
}
}
我找不到错误的确切位置。所以
现在我更新了我的logcat输出：
08-26 11:30:34.351: E/AndroidRuntime(2138): FATAL EXCEPTION: main
08-26 11:30:34.351: E/AndroidRuntime(2138): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.subitemlistviewdb/com.example.subitemlistviewdb.MainActivity}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.app.ActivityThread.access$600(ActivityThread.java:141)
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.os.Handler.dispatchMessage(Handler.java:99)
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.os.Looper.loop(Looper.java:137)
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.app.ActivityThread.main(ActivityThread.java:5041)
08-26 11:30:34.351: E/AndroidRuntime(2138): at java.lang.reflect.Method.invokeNative(Native Method)
08-26 11:30:34.351: E/AndroidRuntime(2138): at java.lang.reflect.Method.invoke(Method.java:511)
08-26 11:30:34.351: E/AndroidRuntime(2138): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
08-26 11:30:34.351: E/AndroidRuntime(2138): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
08-26 11:30:34.351: E/AndroidRuntime(2138): at dalvik.system.NativeStart.main(Native Method)
08-26 11:30:34.351: E/AndroidRuntime(2138): Caused by: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.app.ListActivity.onContentChanged(ListActivity.java:243)
08-26 11:30:34.351: E/AndroidRuntime(2138): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:273)
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.app.Activity.setContentView(Activity.java:1881)
08-26 11:30:34.351: E/AndroidRuntime(2138): at com.example.subitemlistviewdb.MainActivity.onCreate(MainActivity.java:22)
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.app.Activity.performCreate(Activity.java:5104)
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
08-26 11:30:34.351: E/AndroidRuntime(2138): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
08-26 11:30:34.351: E/AndroidRuntime(2138): ... 11 more
08-26 11:35:34.872: I/Process(2138): Sending signal. PID: 2138 SIG: 9
08-26 11:40:04.811: E/Trace(2219): error opening trace file: No such file or directory (2)
08-26 11:40:05.691: D/null(2219): CREATED
08-26 11:40:06.791: D/AndroidRuntime(2219): Shutting down VM
08-26 11:40:06.791: W/dalvikvm(2219): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
这是我的xml文件
<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"
>
<ListView
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
</ListView>
</RelativeLayout>
我使用eclipse IDE
答案 0 :(得分：0)
从文档引用
ListActivity具有默认布局，该布局由屏幕中央的单个全屏列表组成。但是，如果需要，可以通过在onCreate（）中使用setContentView（）设置自己的视图布局来自定义屏幕布局。为此，您自己的视图必须包含一个ID为“@android：id / list”的ListView对象（如果它在代码中则列出）。
因此，请确保您在xml的列表视图中有以下内容
<ListView android:id="@android:id/list"
答案 1 :(得分：0)
从代码中删除l=(ListView) findViewById(R.id.list);行，因为无论何时使用ListActivity，Android都会将列表视图设为@android:id/list，并删除l=getListView();。