我试图从我的 sqlite 数据库中的最后一行获取一个值，并将其用于我的主要活动中的乘法和除法，以获得特定的结果。但我得到的乘法结果为 0，除法结果为“无穷大”。谁能帮忙！！
这是代码
food.java (main activity)
{
//user inputs
ETRate = (EditText)findViewById(R.id.ETRate);
ETFoodQty =(EditText)findViewById(R.id.ETFoodQty;
ETRate.setOnFocusChangeListener(this);
ETFoodQty.setOnFocusChangeListener(this);
FoodStorage foodGetInfo = new FoosStorage(this);
foodGetInfo.open();
foodGetInfo.getAvgTotal(this);
foodGetInfo.close();
chkLastTotal1.setOnCheckedChangeListener(new OnCheckedChangeListener()
{
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// TODO Auto-generated method stub
isChkLastTotal1=true;
}
});
public void onFocusChange(View predictionFocusView, boolean hasPredictionETFocus)
{
if(ETRate.isFocused())
{
if(foodQty!=0) //here I get rate =0
{
rate =(long) (lastTotal*foodQty);
setRate(rate);
ETRate.setText(String.valueOf(rate));
}
}
else if(foodQty.isFocused()) //Here I get foodQty = infinity
{
if(rate!=0)
{
foodQty =rate/avgtotal;
setPredictFoodQty(foodQty);
ETfoodQty.setText(String.valueOf(foodQty));
}
}
foodStorage.java (database file)
public void getAvgtotal(food pd)
{
String [] columns = new String[]{KEY_ROW_ID, KEY_RATE, KEY_FOOD_QTY, KEY_FOOD_PRICE, KEY_QUALITY, KEY_TOTAL, KEY_DATE,KEY_GRADE};
if(pd.isChkLastTotal1()==true)
{
Cursor c= ourDatabase.rawQuery("SELECT * FROM food_table ORDER BY _id DESC LIMIT 1", null);
c.moveToFirst();
if(c!=null && c.getCount()>0)
{
c.moveToLast();
String getLastTotal =c.getString(5);
food myFoodInfo = new Food();
myFoodInfo.setavgTotal(Double.parseDouble(getLastTotal));
}
c.close();
}
}