我对Android编程非常陌生（有一些以前使用php-mysql组合的经验）。通过一些在线教程，我已经为我的mainactivity类设置了一个sqlite适配器用于学习目的。
如果有人可以解释我是否能够获取每个用户输入/输入（例如，条目，日期）并使用它来从mainactivity类本身访问和更新sqlite数据库中的数据，我将不胜感激。
例如，给定用户选择的特定名称，年龄或位置（任何一个），如何使用此信息从主要活动（或托管交换的任何活动）中搜索数据库？
>> MainActivity.......
public class MainActivity extends Activity {
DBAdapter myDb;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myDb = new DBAdapter(this);
myDb.open();
}
@Override
protected void onDestroy() {
super.onDestroy();
myDb.close();
}
private void displayText(String message) {
TextView textView = (TextView) findViewById(R.id.textDisplay);
textView.setText(message);
}
public void onClick_AddRecord(View v) {
displayText("Record added.");
long newId = myDb.insertRow("Kenneth", 17, "Indiana");
Cursor cursor = myDb.getRow(newId);
displayRecordSet(cursor);
}
public void onClick_ClearAll(View v) {
displayText("Clicked clear all!");
myDb.deleteAll();
}
public void onClick_DisplayRecords(View v) {
displayText("Clicked display record!");
Cursor cursor = myDb.getAllRows();
displayRecordSet(cursor);
}
private void displayRecordSet(Cursor cursor) {
String message = "";
if (cursor.moveToFirst()) {
do {
int id = cursor.getInt(DBAdapter.COL_ROWID);
String name = cursor.getString(DBAdapter.COL_NAME);
int ageber = cursor.getInt(DBAdapter.COL_AGE);
String location = cursor.getString(DBAdapter.COL_LOCATION);
message += "id=" + id
+", name=" + name
+", age =" + age
+", location =" + location
+"\n";
} while(cursor.moveToNext());
}
cursor.close();
displayText(message);
}
}
>>> DBAdapter.....
public class DBAdapter {
private static final String TAG = "DBAdapter";
public static final String KEY_ROWID = "_id";
public static final int COL_ROWID = 0;
public static final String KEY_NAME = "name";
public static final String KEY_AGE = "age";
public static final String KEY_LOCATION = "location";
public static final int COL_NAME = 1;
public static final int COL_AGE = 2;
public static final int COL_LOCATION = 3;
public static final String[] ALL_KEYS = new String[] {KEY_ROWID, KEY_NAME, KEY_AGE,
KEY_LOCATION};
public static final String DATABASE_NAME = "MyDb";
public static final String DATABASE_TABLE = "Table";
public static final int DATABASE_VERSION = 23;
private static final String DATABASE_CREATE_SQL =
"create table " + DATABASE_TABLE
+ " (" + KEY_ROWID + " integer primary key autoincrement, "
+ KEY_NAME + " text not null, "
+ KEY_AGE + " integer not null, "
+ KEY_LOCATION + " string null"
+ ");";
private final Context context;
private DatabaseHelper myDBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx) {
this.context = ctx;
myDBHelper = new DatabaseHelper(context);
}
public DBAdapter open() {
db = myDBHelper.getWritableDatabase();
return this;
}
public void close() {
myDBHelper.close();
}
public long insertRow(String name, int age, String location) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_NAME, name);
initialValues.put(KEY_AGE, age);
initialValues.put(KEY_LOCATION, location);
return db.insert(DATABASE_TABLE, null, initialValues);
}
public boolean deleteRow(long rowId) {
String where = KEY_ROWID + "=" + rowId;
return db.delete(DATABASE_TABLE, where, null) != 0;
}
public void deleteAll() {
Cursor c = getAllRows();
long rowId = c.getColumnIndexOrThrow(KEY_ROWID);
if (c.moveToFirst()) {
do {
deleteRow(c.getLong((int) rowId));
} while (c.moveToNext());
}
c.close();
}
public Cursor getAllRows() {
String where = null;
Cursor c = db.query(true, DATABASE_TABLE, ALL_KEYS,
where, null, null, null, null, null);
if (c != null) {
c.moveToFirst();
}
return c;
}
public Cursor getRow(long rowId) {
String where = KEY_ROWID + "=" + rowId;
Cursor c = db.query(true, DATABASE_TABLE, ALL_KEYS,
where, null, null, null, null, null);
if (c != null) {
c.moveToFirst();
}
return c;
}
public boolean updateRow(long rowId, String name, int age, String location) {
String where = KEY_ROWID + "=" + rowId;
ContentValues newValues = new ContentValues();
newValues.put(KEY_NAME, name);
newValues.put(KEY_AGE, age);
newValues.put(KEY_LOCATION, location);
return db.update(DATABASE_TABLE, newValues, where, null) != 0;
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase _db) {
_db.execSQL(DATABASE_CREATE_SQL);
}
@Override
public void onUpgrade(SQLiteDatabase _db, int oldVersion, int newVersion) {
_db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
onCreate(_db);
}
}
}
对不起，如果这个问题对某些人来说太简单了，但我非常渴望学习。
答案 0 :(得分：0)
如果您想要所有记录，请尝试以下代码：
将此代码放在DBAdapter类中：
public ArrayList<HashMap<String, String>> getAlldts() {
ArrayList<HashMap<String, String>> todos = new ArrayList<HashMap<String,String>>();
String selectQuery = "SELECT * FROM " + DATABASE_TABLE;
Log.e(LOG, selectQuery);
SQLiteDatabase db = this.getReadableDatabase();
Cursor c = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (c.moveToFirst()) {
do {
HashMap<String, String> dtls = new HashMap<String, String>();
dtls.put("nm", c.getString((c.getColumnIndex(KEY_NAME))));
dtls.put("age", c.getString((c.getColumnIndex(KEY_AGE))));
dtls.put("loc", c.getString((c.getColumnIndex(KEY_LOCATION))));
todos.add(dtls);
} while (c.moveToNext());
}
return todos;
}
public ArrayList<HashMap<String, String>> getSomedts(int age) {
ArrayList<HashMap<String, String>> todos = new ArrayList<HashMap<String,String>>();
String selectQuery = "SELECT * FROM " + DATABASE_TABLE+ " WHERE " + KEY_AGE + " = " + age+";
Log.e(LOG, selectQuery);
SQLiteDatabase db = this.getReadableDatabase();
Cursor c = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (c.moveToFirst()) {
do {
HashMap<String, String> dtls = new HashMap<String, String>();
dtls.put("nm", c.getString((c.getColumnIndex(KEY_NAME))));
dtls.put("age", c.getString((c.getColumnIndex(KEY_AGE))));
dtls.put("loc", c.getString((c.getColumnIndex(KEY_LOCATION))));
todos.add(dtls);
} while (c.moveToNext());
}
return todos;
}
现在在您的活动类中使用此方法，如下所示：
ArrayList<HashMap<String, String>> Mondtls = new ArrayList<HashMap<String, String>>();
Mondtls = db.getAlldts(); // db.getSomedts(25);
for (int i = 0; i < Mondtls.size(); i++) {
String nm= Mondtls.get(i).get("nm");
String age = Mondtls.get(i).get("age");
String loc = Mondtls.get(i).get("loc");
}
现在根据您的需要使用它。