我在这里没有收到任何错误，但我无法在屏幕上显示任何内容 我有2个XML文件main.xml有一个id @ id / android：list列表视图，另一个xml有一个相对布局，有3个文本视图我试图显示数据库中的数据，但似乎没有任何结果。我尝试了简单的列表布局，然后我能够显示数据库中其中一列的内容。但是，当我尝试使用自定义布局时，除了空行外没有显示任何内容。
这是启动应用程序时启动的主要活动。
public class Db extends ListActivity {
private SQLiteDatabase newDb;
DataBaseHelper myDbHelper = new DataBaseHelper(this);
public ListAdapter adapter;
private ArrayList<String> results = new ArrayList<String>();
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
openDatabase();
newDb = myDbHelper.getReadableDatabase();
Cursor c = newDb.rawQuery("SELECT _id, organisation, address, postcode FROM shoplist", null);
int i_organisation = c.getColumnIndex("organisation");
int i_id = c.getColumnIndex("_id");
int i_address = c.getColumnIndex("address");
int i_postcode = c.getColumnIndex("postcode");
//int count = c.getCount();
//String data[] = new String[count];
//int i= 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext())
{
String i1 = c.getString(c.getColumnIndex("_id"));
String i2 = c.getString(c.getColumnIndex("organisation"));
String i3 = c.getString(c.getColumnIndex("address"));
results.add(i1);
//i++;
}
customAdapter adapter = new customAdapter(getApplicationContext(),
R.layout.main, results, results, results);
setListAdapter(adapter);
}
private long inserttodata() {
// TODO Auto-generated method stub
ContentValues cv = new ContentValues();
cv.put("id", "112");
cv.put("organisation","test" );
return newDb.insert("shoplist", null, cv);
}
private void openDatabase() {
try {
myDbHelper.createDataBase();
} catch (IOException ioe) {
throw new Error("Unable to create database");
}
try {
myDbHelper.openDataBase();
} catch (SQLException sqle) {
System.out.println("failed to open");
throw sqle;
}
//String[] columns= new String[]{"_id", "Organisation"};
//cursor = newDb.query("Shop", columns, null, null, null, null, null);
}
}
我的数据库助手类
public class DataBaseHelper extends SQLiteOpenHelper{
//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/calc.three/databases/";
private static String DB_NAME = "charity.db";
private SQLiteDatabase myDataBase;
private final Context myContext;
public DataBaseHelper(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
public void createDataBase() throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exist
}else{
//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[2048];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException{
//Open the database
String myPath = DB_PATH + DB_NAME;
SQLiteDatabase.CursorFactory c = null;
myDataBase = SQLiteDatabase.openDatabase(myPath, c , SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}}
我的自定义适配器类
public class customAdapter extends ArrayAdapter<String> {
static List<String> serialNo = new ArrayList<String>();
static List<String> name = new ArrayList<String>();
static List<String> address = new ArrayList<String>();
Context myContext;
public customAdapter(Context context, int resource, List<String> c_serialNo,
List<String> c_name, List<String> c_address) {
super(context, resource, c_serialNo);
myContext = context;
serialNo = c_serialNo;
name = c_name;
address = c_address;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater vi = (LayoutInflater) myContext
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.main, null);
}
TextView tv_serialNo = (TextView) v.findViewById(R.id.serialNo);
TextView tv_name = (TextView) v.findViewById(R.id.name);
TextView tv_address = (TextView) v.findViewById(R.id.address);
if (tv_serialNo != null) {
tv_serialNo.setText(serialNo.get(position));
}
if (tv_name != null) {
tv_name.setText(name.get(position));
}
if (tv_address!= null) {
tv_address.setText(address.get(position));
}
return v; }}
main.xml文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<ListView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@id/android:list"></ListView>
</LinearLayout>
custom_list.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<RelativeLayout android:layout_width="fill_parent" android:layout_height="80dp" >
<TextView android:id="@+id/serialNo"
android:layout_height="38dp"
android:layout_width="40dp"
android:padding="1dip"
android:gravity="top"
android:text="sn"
/>
<TextView android:id="@+id/name"
android:layout_height="38dp"
android:layout_width="240dp"
android:padding="1dip"
android:gravity="top"
android:text="name"
android:layout_toRightOf="@id/serialNo"
/>
<ImageButton
android:id="@+id/fav"
android:layout_width="38dp"
android:layout_height="38dp"
android:layout_alignParentTop="true"
android:layout_toRightOf="@+id/name"
android:src="@drawable/ic_launcher" />
<TextView android:id="@+id/address"
android:layout_height="40dp"
android:layout_width="300dp"
android:padding="1dip"
android:text="name"
android:layout_below="@id/serialNo"
/>
<ImageView
android:id="@+id/source"
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_alignBottom="@+id/address"
android:layout_toRightOf="@+id/address"
android:src="@drawable/pg" />
</RelativeLayout>
</LinearLayout>
答案 0 :(得分：0)
我看到的一些事情...... R.layout main是您的主要布局，您尝试将其设置为适配器的行布局。两者应该是不同的。
其次，除非你有一些不明显的原因，否则你正在做很多额外的工作来创建数组......
第三，看起来你试图列出未从光标或你所显示的任何其他数组（serialNo）中提取的内容。
使用像这样的SimpleCursorAdapter会简单得多：
openDatabase();
newDb = myDbHelper.getReadableDatabase();
Cursor c = newDb.rawQuery("SELECT _id, organisation, address, postcode FROM shoplist", null);
// let the system manage your cursor
getActivity().startManagingCursor(c);
// tell the adapter what columns to pull data from
String[] from = new String[] { "_id", "organisation", "address" };
// tell the adapter what resource ids in your row layout to map the data to
int[] to = new int[] { R.id.serialNo, R.id.name, R.id.address };
// create the adapter, specifying the context, the xml file to use for the row layout, the cursor to pull the data from, and the map of where to put the data in the form of from and to arrays
SimpleCursorAdapter mAdapter = new SimpleCursorAdapter(this, R.layout.your_row_xml, c, from, to);
// set the adapter to your list
setListAdapter(mAdapter);
答案 1 :(得分：0)
解决：我正在膨胀错误的XMl文件。 inflate custom_list.xml，它开始显示。