設置和訪問各種類的布爾值

Question

我想在android中對我的數據庫（add，del，edit）進行任何更新時設置一個'flag'。我通過在數據庫適配器類中創建一個getter和setter方法來做到這一點：

Boolean updateOnlineDatabase =  false;

public Boolean updateNeeded() {
    return updateOnlineDatabase;
}

public void setUpdateNeeded(Boolean bool) {
    updateOnlineDatabase = bool;
}

所以在其他班上我一直在打電話

adapter.setUpdateNeeded(true);

但是，當我嘗試使用以下updateNeeded()返回值時： updateNeeded()始終返回false。

添加完整的類。

這里是數據庫適配器類

public class MySQLiteAdapters {
SQLiteDatabase database_ob;
MySQLiteHelper openHelper_ob;
Context context;
Boolean updateOnlineDatabase =  false;

public MySQLiteAdapters(Context c) {
    context = c;
}

public MySQLiteAdapters opnToRead() {
    openHelper_ob = new MySQLiteHelper(context,
            openHelper_ob.DATABASE_NAME, null, openHelper_ob.DATABASE_VERSION);
    database_ob = openHelper_ob.getReadableDatabase();
    return this;

}
public void del(){
    database_ob.execSQL("DROP TABLE IF EXISTS " + openHelper_ob.TABLE_PLAYER_INFO);
}

public MySQLiteAdapters opnToWrite() {
    openHelper_ob = new MySQLiteHelper(context,
            openHelper_ob.DATABASE_NAME, null, openHelper_ob.DATABASE_VERSION);
    database_ob = openHelper_ob.getWritableDatabase();
    database_ob.execSQL("PRAGMA foreign_keys = ON;");
    return this;

}

public void Close() {
    database_ob.close();
}

public long insertDetails(String fname, String lname, String age, String heightValue, String weightValue, String positionValue, String teamValue, String notPicked, int match_no) {
    ContentValues contentValues = new ContentValues();
    contentValues.put(openHelper_ob.KEY_FNAME, fname);
    contentValues.put(openHelper_ob.KEY_LNAME, lname);
    contentValues.put(openHelper_ob.KEY_AGE, age);
    contentValues.put(openHelper_ob.KEY_HEIGHT, heightValue);
    contentValues.put(openHelper_ob.KEY_WEIGHT , weightValue);
    contentValues.put(openHelper_ob.KEY_POSITION, positionValue);
    contentValues.put(openHelper_ob.TEAM_ID, lookupOrCreateTeamID(teamValue));
    contentValues.put(openHelper_ob.KEY_PICKED, notPicked);
    contentValues.put(openHelper_ob.KEY_PICKED_NO, match_no);
    //testing the foreign key constraint
    //contentValues.put(openHelper_ob.TEAM_ID, "30");
    opnToWrite();
    long val = database_ob.insert(openHelper_ob.TABLE_PLAYER_INFO, null,
            contentValues);
    Close();
    return val;

}

public long lookupOrCreateTeamID(String name) {
    opnToWrite();
    Cursor c = database_ob.query(openHelper_ob.TABLE_TEAM_INFO, new String[] { openHelper_ob.KEY_TEAM_ID },
            openHelper_ob.KEY_TEAMNAME + " = ?", new String[] { name }, null, null, null);
    if (c.moveToFirst())
        return c.getLong(0);
    else {
        ContentValues cv = new ContentValues();
        cv.put(openHelper_ob.KEY_TEAMNAME, name);
        return database_ob.insert(openHelper_ob.TABLE_TEAM_INFO, null, cv);
    }

}

public long insertTeamDetails(String teamName) {
    ContentValues contentValues = new ContentValues();
    contentValues.put(openHelper_ob.KEY_TEAMNAME, teamName);
    opnToWrite();
    long val = database_ob.insert(openHelper_ob.TABLE_TEAM_INFO, null,
            contentValues);
    Close();
    Log.i("INSERT TEAM", "inserted" + teamName + "into" + openHelper_ob.TABLE_TEAM_INFO);
    return val;

}

// Return list of players depending on current team in alphabetical order
public Cursor queryName(String filterTeam) {
    String[] context = {filterTeam};
    opnToWrite();
    Cursor mCursor = database_ob.rawQuery("SELECT PLAYER_Local._id AS p_id, * FROM PLAYER_Local, TEAM_local " 
            + "WHERE PLAYER_Local.team_id = TEAM_local._id "
            + "AND team_name = ? "
            + "ORDER BY first_name ", context);

    return mCursor;
}

// Return the list of teams 
public Cursor queryTeamName() {
    String[] cols = {openHelper_ob.KEY_PLAYER_ID, openHelper_ob.KEY_TEAMNAME};
    opnToWrite();
    Cursor c = database_ob.query(openHelper_ob.TABLE_TEAM_INFO, cols, null,
            null, null, null, null);
    return c;

}

public Cursor queryAll(int nameId) {
    String[] cols = { openHelper_ob.KEY_PLAYER_ID, openHelper_ob.KEY_FNAME,
            openHelper_ob.KEY_LNAME, openHelper_ob.KEY_HEIGHT, openHelper_ob.KEY_WEIGHT, openHelper_ob.KEY_POSITION };
    opnToWrite();
    Cursor c = database_ob.query(openHelper_ob.TABLE_PLAYER_INFO, cols,
            openHelper_ob.KEY_PLAYER_ID + "=" + nameId, null, null, null, null);

    return c;

}

public Cursor queryRecord(int nameId) {
    String[] cols = {openHelper_ob.KEY_FNAME,openHelper_ob.KEY_LNAME};
    opnToWrite();
    Cursor c = database_ob.query(openHelper_ob.TABLE_PLAYER_INFO, cols,
            openHelper_ob.KEY_PLAYER_ID + "=" + nameId, null, null, null, null);

    return c;

}

public Cursor getPickedPlayer(int playerNo) {
    String[] cols = {openHelper_ob.KEY_FNAME,openHelper_ob.KEY_LNAME};
    opnToWrite();
    Cursor c = database_ob.query(openHelper_ob.TABLE_PLAYER_INFO, cols,
            openHelper_ob.KEY_PICKED_NO + "=" + playerNo, null, null, null, null);
    return c;

}

public long updateldetail(int rowId, String fname, String lname, String heightValue, String weightValue, String positionValue) {
    ContentValues contentValues = new ContentValues();
    contentValues.put(openHelper_ob.KEY_FNAME, fname);
    contentValues.put(openHelper_ob.KEY_LNAME, lname);
    contentValues.put(openHelper_ob.KEY_HEIGHT, heightValue);
    contentValues.put(openHelper_ob.KEY_WEIGHT , weightValue);
    contentValues.put(openHelper_ob.KEY_POSITION, positionValue);
    opnToWrite();
    long val = database_ob.update(openHelper_ob.TABLE_PLAYER_INFO, contentValues,
            openHelper_ob.KEY_PLAYER_ID + "=" + rowId, null);
    Close();
    return val;
}

public int deletOneRecord(int rowId) {
    // TODO Auto-generated method stub
    opnToWrite();
    int val = database_ob.delete(openHelper_ob.TABLE_PLAYER_INFO,
            openHelper_ob.KEY_PLAYER_ID + "=" + rowId, null);
    Close();
    //// add teamName to team_updates > del_player > player_ID
    return val;
}

 public List<String> getAllLabels(){
     List<String> labels = new ArrayList<String>();
    // Select All Query
        String selectQuery = "SELECT  * FROM " + openHelper_ob.TABLE_TEAM_INFO;

        opnToRead();
        Cursor cursor = database_ob.rawQuery(selectQuery, null);

        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                labels.add(cursor.getString(1));
            } while (cursor.moveToNext());
        }

        // closing connection
        cursor.close();
        database_ob.close();

        // returning lables

    return labels;

 }

public long playerPicked(int playerRecord, String string, int pos) {
    ContentValues contentValues = new ContentValues();
    contentValues.put(openHelper_ob.KEY_PICKED, string);
    contentValues.put(openHelper_ob.KEY_PICKED_NO, pos);
    opnToWrite();
    long val = database_ob.update(openHelper_ob.TABLE_PLAYER_INFO, contentValues,
            openHelper_ob.KEY_PLAYER_ID + "=" + playerRecord, null);
    Close();
    return val;
}

public Cursor queryUpdatedPlayerList(String team, String filter2) {
    String[] context = {team};
    opnToWrite();
    Cursor mCursor = database_ob.rawQuery("SELECT PLAYER_Local._id AS p_id, * FROM PLAYER_Local, TEAM_local " 
            + "WHERE PLAYER_Local.team_id = TEAM_local._id "
            + "AND team_name = ? "
            + "AND  p_id not in ("+filter2+")" 
            + "ORDER BY first_name ", context);

    return mCursor;
}

public void resetPickedPlayers() {
    ContentValues contentValues = new ContentValues();
    contentValues.put(openHelper_ob.KEY_PICKED, "NO");
    contentValues.put(openHelper_ob.KEY_PICKED_NO, 0);
    //testing the foreign key constraint
    //contentValues.put(openHelper_ob.TEAM_ID, "30");
    opnToWrite();
    long val = database_ob.update(openHelper_ob.TABLE_PLAYER_INFO, contentValues,null, null);
    Close();

}

public Boolean updateNeeded() {
    return updateOnlineDatabase;
}

public void setUpdateNeeded(Boolean bool) {
    updateOnlineDatabase = bool;
}

我將Boolean設置為True的類之一：

public class AddPlayerActivity extends Activity {
MySQLiteAdapters adapter; 
MySQLiteHelper helper;
EditText fnameEdit, lnameEdit, ageEdit, heightEdit, weightEdit, positionEdit;
String teamEdit, json, jsonString;
Button submitBtn, resetBtn;
SharedPreferences exmaple;
Editor editor;
public static final String PREFS = "examplePrefs";



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Bundle extras = getIntent().getExtras();
    setContentView(R.layout.activity_add_player);
    fnameEdit = (EditText) findViewById(R.id.et_fname);
    lnameEdit = (EditText) findViewById(R.id.et_lname);
    ageEdit = (EditText) findViewById(R.id.et_age);
    heightEdit = (EditText) findViewById(R.id.et_height);
    weightEdit = (EditText) findViewById(R.id.et_weight);
    positionEdit = (EditText) findViewById(R.id.et_position);
    submitBtn = (Button) findViewById(R.id.btn_submit);
    resetBtn = (Button) findViewById(R.id.btn_reset);
    adapter = new MySQLiteAdapters(this);

    exmaple = getSharedPreferences(PREFS, 0);
    teamEdit = exmaple.getString("teamName", "cant find team");
    editor = exmaple.edit();
    json = exmaple.getString("ChangesJSON", "cant find Changes_json");

    submitBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            // sets flag to update online database.
            adapter.setUpdateNeeded(true);
            // add name to database
            String fnameValue = fnameEdit.getText().toString();
            String lnameValue = lnameEdit.getText().toString();
            String heightValue = heightEdit.getText().toString();
            String weightValue = weightEdit.getText().toString();
            String positionValue = positionEdit.getText().toString();
            String ageValue = ageEdit.getText().toString();
            String teamValue = teamEdit;
            adapter.insertDetails(fnameValue, lnameValue, ageValue, heightValue, weightValue, positionValue, teamValue, "NO",0);
            //// add above to team_updates > add_player > above

         // Logic to add changes to JSON to update remote database
            JSONObject MainObj = null;
            try {
                MainObj = new JSONObject(json);
            } catch (JSONException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }

            JSONObject obj = new JSONObject();
            try {
                obj.put("first_name", fnameValue);
                obj.put("last_name", lnameValue);
                obj.put("age", ageValue);
                obj.put("height", heightValue);
                obj.put("weight", weightValue);
                obj.put("position", positionValue);
                MainObj.accumulate("New_Players", obj);
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            try {
                 jsonString = MainObj.toString(3);
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            editor.putString("ChangesJSON", jsonString);
            editor.commit();



            Log.i("Submit Button", "CLICKED");
            fnameEdit.setText("");
            lnameEdit.setText("");
            heightEdit.setText("");
            weightEdit.setText("");
            positionEdit.setText("");
            ageEdit.setText("");
        }
    });

    resetBtn.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            fnameEdit.setText("");
            lnameEdit.setText("");
            heightEdit.setText("");
            weightEdit.setText("");
            positionEdit.setText("");
            ageEdit.setText("");
        }
    });



}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.add_player, menu);
    return true;
}

}

這是我打電話給updateNeeded()

if(adapter.updateNeeded()){
            JSONObject main = new JSONObject(exmaplePrefs.getString("jsonString", "cant find json"));
            JSONObject dbUpdates = new JSONObject(exmaplePrefs.getString("ChangesJSON", "cant find Changejson"));
            main.put("Team_Updates", dbUpdates);
            json = main.toString();
        }else{
             json = exmaplePrefs.getString("jsonString", "cant find json");
             // String json = "{\"twitter\":\"test\",\"country\":\"test\",\"name\":\"test\"}";
        }

Answer 1

您將在此處創建適配器的新副本。 如果其他類都在做同樣的事情，那么它們都在與不同的實例通信。

adapter = new MySQLiteAdapters(this);

單例將對此有所幫助，但您必須小心使其線程安全。 如果未同步，並且兩個線程嘗試同時使用它，則會收到ConcurrencyException 。

class MySingleton {
    private static MySingleton instance = null;

    // Prevent it from being instantiated
    MySingleton() {}

    public static synchronized MySingleton getInstance() {
        if (instance == null) {
            instance = this;
        }
        return instance;
    }
}

然后只需使用adapter = MySingleton.getInstance(); 當您需要使用它時。