如何从SQLite数据库中提取数据并在列表视图中显示它。
我在我的代码中这样做，但是我收到了一个错误：
public class ShoewDataListActivity extends ListActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.grupadd);
Button btnAdd = (Button) findViewById(R.id.btnAdd);
Button view=(Button) findViewById(R.id.btnShowData);
view.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
displayResultList();
}
});
btnAdd.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
boolean didItWork = true;
try {
EditText edtAddName=(EditText) findViewById(R.id.editNameAdd);
String name = edtAddName.getText().toString();
AddData entry = new AddData(ShoewDataListActivity.this);
entry.open();
entry.createEntry(name);
entry.close();
} catch (Exception e) {
// e.printStackTrace();
didItWork = false;
String error = e.toString();
Dialog d = new Dialog(ShoewDataListActivity.this);
d.setTitle("What happend...!!");
TextView tv = new TextView(ShoewDataListActivity.this);
tv.setText("...." + error + "....");
d.setContentView(tv);
d.show();
} finally {
if (didItWork) {
// Dialog d = new Dialog(GroupActivity.this);
// d.setTitle("This is ok..........!!");
// TextView tv= new TextView(GroupActivity.this);
// tv.setText("....SuccessFull....");
// d.setContentView(tv);
// d.show();
Toast.makeText(getBaseContext(), "Project Saved",
Toast.LENGTH_LONG).show();
}
}
}
});
}
private void displayResultList() {
TextView tView = new TextView(this);
AddData info = new AddData(this);
ArrayList<String> results = new ArrayList<String>();
results = info.fatchData();
tView.setText("This data is retrieved from the database and only 4 "
+ "of the results are displayed");
getListView().addHeaderView(tView);
setListAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, results));
getListView().setTextFilterEnabled(true);
}
}
我的Dbhelper课程是：
public class AddData {
public static final String TAG = DbHelper.class.getSimpleName();
public static final String DB_NAME = "Grup.db";
public static final int DB_VERSION = 1;
public static final String TABLE = "Grups";
public static final String C_ID = BaseColumns._ID;
public static final String C_CREATED_AT = "easy_ass_created_At";
public static final String C_NAME = "name";
private DbHelper ourHelper;
private final Context ourContext;
private SQLiteDatabase ourDatabase;
public class DbHelper extends SQLiteOpenHelper {
// public static final String TAG = DbHelper.class.getSimpleName();
// public static final String DB_NAME = "Grup.db";
// public static final int DB_VERSION = 1;
// public static final String TABLE = "Grups";
// public static final String C_ID = BaseColumns._ID;
// public static final String C_CREATED_AT = "easy_ass_created_At";
// public static final String C_NAME = "name";
public DbHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql = ("create table " + TABLE + " ( " + C_ID
+ " integer primary key autoincrement, " + C_NAME
+ " text not null" + ");");
db.execSQL(sql);
Log.d(TAG, "OnCreate sql" + sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists " + TABLE);
this.onCreate(db);
Log.d("TAG", "********On Upgrate Drop Table*****");
}
}
public AddData(Context context) {
ourContext = context;
}
public AddData open() throws SQLException {
ourHelper = new DbHelper(ourContext);
ourDatabase = ourHelper.getReadableDatabase();
return this;
}
public void close() {
ourHelper.close();
}
public long createEntry(String name) {
ContentValues cv = new ContentValues();
cv.put(C_NAME, name);
return ourDatabase.insert(TABLE, null, cv);
}
public String getData() {
String[] columns = new String[] { C_ID, C_NAME };
Cursor c = ourDatabase.query(TABLE, columns, null, null, null, null,
null);
String result = "";
// int iRow=c.getColumnIndex(C_ID);
int iName = c.getColumnIndex(C_NAME);
// for(c.moveToFirst();!c.isAfterLast();c.moveToLast()){
for (boolean hasItem = c.moveToFirst(); hasItem; hasItem = c
.moveToNext()) {
result = result + " " + c.getString(iName) + "\n";
c.moveToNext();
}
c.close();
return result;
}
public ArrayList<String> fatchData(){
String[] columns = new String[] { C_ID, C_NAME };
Cursor c = ourDatabase.query(TABLE, columns, null, null, null, null,
null);
String result="";
ArrayList<String> result1=new ArrayList<String>();
// int iRow=c.getColumnIndex(C_ID);
int iName = c.getColumnIndex(C_NAME);
// for(c.moveToFirst();!c.isAfterLast();c.moveToLast()){
for (boolean hasItem = c.moveToFirst(); hasItem; hasItem = c
.moveToNext()) {
result = " " + c.getString(iName) + "\n";
result1.add(result);
c.moveToNext();
}
c.close();
return result1;
}
}
答案 0 :(得分：2)
试试这个，
的AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.collabera.labs.sai.db"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".CRUDonDB"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-sdk android:minSdkVersion="3" />
</manifest>
活动文件
import java.util.ArrayList;
import android.app.ListActivity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
public class CRUDonDB extends ListActivity {
private final String SAMPLE_DB_NAME = "myFriendsDb";
private final String SAMPLE_TABLE_NAME = "friends";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ArrayList<String> results = new ArrayList<String>();
SQLiteDatabase sampleDB = null;
try {
sampleDB = this.openOrCreateDatabase(SAMPLE_DB_NAME, MODE_PRIVATE, null);
sampleDB.execSQL("CREATE TABLE IF NOT EXISTS " +
SAMPLE_TABLE_NAME +
" (LastName VARCHAR, FirstName VARCHAR," +
" Country VARCHAR, Age INT(3));");
sampleDB.execSQL("INSERT INTO " +
SAMPLE_TABLE_NAME +
" Values ('Makam','Sai Geetha','India',25);");
sampleDB.execSQL("INSERT INTO " +
SAMPLE_TABLE_NAME +
" Values ('Chittur','Raman','India',25);");
sampleDB.execSQL("INSERT INTO " +
SAMPLE_TABLE_NAME +
" Values ('Solutions','Collabera','India',20);");
Cursor c = sampleDB.rawQuery("SELECT FirstName, Age FROM " +
SAMPLE_TABLE_NAME +
" where Age > 10 LIMIT 5", null);
if (c != null ) {
if (c.moveToFirst()) {
do {
String firstName = c.getString(c.getColumnIndex("FirstName"));
int age = c.getInt(c.getColumnIndex("Age"));
results.add("" + firstName + ",Age: " + age);
}while (c.moveToNext());
}
}
this.setListAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,results));
} catch (SQLiteException se ) {
Log.e(getClass().getSimpleName(), "Could not create or Open the database");
} finally {
if (sampleDB != null)
sampleDB.execSQL("DELETE FROM " + SAMPLE_TABLE_NAME);
sampleDB.close();
}
}
}
答案 1 :(得分：1)
不是编写查询，而是通过使用ORMAN for android来节省大量时间，请参阅以下链接 http://codeherenow.com/android/orman-saying-hello-part-2/ https://github.com/ahmetalpbalkan/orman
答案 2 :(得分：0)
首先要检查在Dbhelper类中正确插入的数据
public long createEntry(String name)
{
ContentValues cv = new ContentValues();
cv.put(C_NAME, name);
long a=ourDatabase.insert(TABLE, null, cv);
if (a > 0)
Log.d("Call properly", "working");
else
Log.d("Call properly", "not working");
}
然后使用你的fatchData（）方法：
String[] columns = new String[] { C_ID, C_NAME };
public ArrayList<HashMap<String, String>> retrieve() {
ArrayList<HashMap<String, String>> ar = new ArrayList<HashMap<String, String>>();
try
{
Cursor c = db.query("LOGIN", strcol, null, null, null, null, null);
c.moveToNext();
while (!c.isAfterLast()) {
String dat = c.getString(0);
String tim = c.getString(1);
// String due=c.getString(2);
// String end=c.getString(3);
// String cat=c.getString(4);
// String not=c.getString(5);
String titl = c.getString(2);
HashMap<String, String> hmap = new HashMap<String, String>();
hmap.put("date", dat);
hmap.put("time", tim);
hmap.put("title", titl);
ar.add(hmap);
c.moveToNext();
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
Log.e("Check ar size at ret", "" + ar.size());
return ar;
}
然后在Activty文件中尝试这样的代码：
public class List_activity extends Activity {
Login_database login_database;
ListView lv;
Dialog listDialog;
ArrayList<HashMap<String, String>> al;
Button btn1,btn2,edt_data;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.list_view1);
edt_data=(Button)findViewById(R.id.btn_edt_data);
edt_data.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
}
});
try
{
login_database=new Login_database(this);
login_database.open();
}
catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
try {
al=login_database.retrieve();
ListAdapter ld=new SimpleAdapter(List_activity.this, al, R.layout.list_view, new String[]{"date","time","title"}, new int[]{R.id.listDesignTxtDate,R.id.listDesignTxtTime,R.id.listDesignTxtTitle});
ArrayAdapter ad=new ArrayAdapter(List_activity.this,android.R.layout.simple_listitem,al);
lv=(ListView)findViewById(R.id.lv1);
lv.setAdapter(ld);
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}