Android值无法在textview中设置

Question

我有一个SQLite数据库 add2cart ，它存储了添加到购物车的产品的详细信息。我需要在文本视图中显示每个用户在购物车中拥有的产品数量。 crtno 是我的textview。我想在每个用户点击add2cart按钮时在textview中显示数字。

码

  protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.product_dtls);

    name = (TextView) findViewById(R.id.txtPr_name);
    price = (TextView) findViewById(R.id.txtprice);
    specification=(TextView)findViewById(R.id.txtPr_spec);
    feature=(TextView)findViewById(R.id.txtPr_feature);

    crtno=(TextView)findViewById(R.id.crtno);

    add2cart=(Button)findViewById(R.id.add2cart);

    DataBaseHandler dbh = new DataBaseHandler(this);
    SQLiteDatabase db = dbh.getWritableDatabase();
    Intent in = getIntent();
    Bundle bn = in.getExtras();
    Bundle bun=in.getExtras();
    final String dtl=bun.getString("key");
    nme = bn.getString("name");

    Cursor cr = db.rawQuery("SELECT * FROM product WHERE pname = '"+nme+"'", null);

    while(cr.moveToNext())
    {
        String name = cr.getString(cr.getColumnIndex("pname"));
        String pr1price = cr.getString(cr.getColumnIndex("pprice"));
        String prspc=cr.getString(cr.getColumnIndex("pspec"));
        String prfeature=cr.getString(cr.getColumnIndex("pfeature"));
        pname = name;
        prprice = pr1price;
        pspec=prspc;
        pfeature=prfeature;
    }
    name.setText(pname);
    price.setText("Rs " +prprice + "/-");
    specification.setText(pspec);
    feature.setText(pfeature);


    add2cart.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            boolean incart=false;
            String nm=name.getText().toString();

            mydb=Product_Details.this.openOrCreateDatabase("addcart", MODE_PRIVATE, null);
            mydb.execSQL("CREATE TABLE IF NOT EXISTS add2cart(usr TEXT,img BLOB,pnme TEXT,prate NUMERIC,pqty NUMERIC,ptotl NUMERIC)");
            Cursor cur=mydb.rawQuery("select * from add2cart where pnme='"+nm+"' AND usr='"+dtl+"'",null);

            if (cur.moveToFirst()){
                String prdname=cur.getString(cur.getColumnIndex("pnme"));

                if (nm.equals(prdname)){
                    add2cart.setText("Already in Cart");
                    incart=true;
                }
            }

            if(incart==false){
                mydb.execSQL("INSERT INTO add2cart (usr,pnme,prate)VALUES('"+dtl+"','"+nm+"','"+prprice+"')");
                Toast.makeText(getApplicationContext(),"added to cart",Toast.LENGTH_SHORT).show();
                Cursor crsr=mydb.rawQuery("select pnme from add2cart where usr='"+dtl+"'", null);



//                  int count=0;
           Boolean val=false;
           int  count=crsr.getCount();
Toast.makeText(getApplicationContext(),"count"+count, Toast.LENGTH_LONG).show();
crtno.setText(Integer.toString(count));
//             abc=crtno.getText().toString();
                if (crtno!=null) {
                                    val=true;                       
                    crtno.setText(Integer.toString(count));
                }
                if (val=false) {
                crtno.setText("0");


                }

            }


        }
    });
}
}

Answer 1

改变条件。（确保你已经完成了上面的onclick听众卡通= findviewbyId ....）

if(count != null && count > 0){

   crtno.setText(count+"");

}else{

  crtno.setText("0");
}