android数据库获取nullpointer异常

Question

我正在尝试将值加载到android上的SQLite表中。当我点击按钮时，我得到了nullpointer异常。请查找logcat.so的附加图像，以将值存储到sqlite数据库表中。

    public class MainActivity extends Activity {


    EditText edt1,edt2; 
    DataAdapter adapter;
    //String valueName,valueAddress;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    //  database =new DataAdapter(this);        
        edt1 =(EditText)findViewById(R.id.editText1);
        edt2 =(EditText)findViewById(R.id.editText2);   
        // sdb = database.getWritableDatabase();

        Button button =(Button)findViewById(R.id.button1);

        button.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                String  valueName =edt1.getText().toString().trim();
                String  valueAddress =edt2.getText().toString().trim(); 
             long value = adapter.insertData(valueName,valueAddress);   

             if (value < 0) {

                 Toast.makeText(getApplicationContext(), "Data not Added ",Toast.LENGTH_SHORT).show();
            } else {
                 Toast.makeText(getApplicationContext(), "Data Added",Toast.LENGTH_SHORT).show();
            }                           
            }               
        });

    }

}


public class DataAdapter {

       DataBase database;
       SQLiteDatabase db;      

public DataAdapter(Context context) {
    // TODO Auto-generated constructor stub
    database =new DataBase(context);    
}

public long insertData(String name ,String address){    

    SQLiteDatabase db= database.getWritableDatabase();  
    ContentValues values = new ContentValues();
    values.put(DataBase.NAME, name);
    values.put(DataBase.ADDRESS, address);
    return db.insert(DataBase.TABLENAME, null,values);
    }

public static class DataBase extends SQLiteOpenHelper{

    public static final String DATABASE="DataBase";
    public static final String TABLENAME="TableName";   
    public static final int VERSION = 5;
    public static final String NAME="name"; 
    public static final String ADDRESS="address";
    public static final String ID="_id";

    public static final String CREATE_TABLE = "create table "+TABLENAME+"("+ID+"" +
            "INTEGER PRIMARY KEY AUTOINCREMENT,"+NAME+" VARCHAR(255),"+ADDRESS+"  VARCHAR(255));";

    private Context context;

    public DataBase(Context context) {
        super(context, DATABASE, null, VERSION);        
        this.context =context;
        // TODO Auto-generated constructor stub     
        Toast.makeText(context, "onDataBase",Toast.LENGTH_SHORT).show();

    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub

        try {
            Toast.makeText(context, "oncreate",Toast.LENGTH_SHORT).show();
            db.execSQL(CREATE_TABLE);
        } catch (SQLException e) {
            // TODO: handle exception
        }       

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub
        try {
            Toast.makeText(context, "oncUpgrade",Toast.LENGTH_SHORT).show();
            db.execSQL("DROP TABLE IF EXITS"+TABLENAME);
            onCreate(db);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}   



}][1]

Answer 1

 DataAdapter adapter;

未在您的代码中初始化，请将其初始化，然后使用.. like

adapter = new DataAdapter(this);