Question

首先是我的代码：

public class MainActivity extends AppCompatActivity
{
Spinner dropdown;
EditText e1;  //user enters the bill amount before tip here
TextView tipped; //total tipped amount
TextView Bill;  //the total amount of the bill including tax
String sdropdown;
double originalBill = 0;  //amount that the user enters converted to a double
double result = 0;  //result of multiplying bill and tax
String test1;  //editText field has to be converted to a string value first
NumberFormat currencyFormat = NumberFormat.getCurrencyInstance();  //currency format object



//Create array of items
String tip [] = {"10%", "15%", "20%", "25%", "30%"};

//Create ArrayAdaptor
ArrayAdapter<String> adaptorTipAmount;


@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //Create the element
    dropdown = (Spinner) findViewById(R.id.tipAmount);
    tipped = (TextView) findViewById(R.id.tipTotal);
    Bill = (TextView) findViewById(R.id.billTotal);
    e1 = (EditText) findViewById(R.id.billAmount);
    tipped.setText(currencyFormat.format(0));
    Bill.setText(currencyFormat.format(0));


    //initialize and set adaptor
    adaptorTipAmount = new ArrayAdapter<String>(this,
            android.R.layout.simple_spinner_item, tip);

    adaptorTipAmount.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    dropdown.setAdapter(adaptorTipAmount);



    dropdown.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapter, View v,
                                   int position, long id) {

            // On selecting a spinner item
            sdropdown = adapter.getItemAtPosition(position).toString();

            //what editText field is initially stored in
            test1 = e1.getText().toString();

            //test1 string variable gets converted to a double
            //originalBill = Double.parseDouble(test1);



            //determines the tip amount and does the calculation based on the tip
           /* if (sdropdown.equals("10%"))
            {
                result = originalBill * .10;
                tipped.setText(Double.toString(result));
            }
            else if (sdropdown.equals("15%"))
            {
                result = originalBill * .15;
                tipped.setText(Double.toString(result));
            }
            else if (sdropdown.equals("20%"))
            {
                result = originalBill * .20;
                tipped.setText(Double.toString(result));
            }
            else if (sdropdown.equals("25%"))
            {
                result = originalBill * .25;
                tipped.setText(Double.toString(result));
            }
            else if (sdropdown.equals("30%"))
            {
                result = originalBill * .30;
                tipped.setText(Double.toString(result));
            }
            */
            tipped.setText("The tipped amount is: " + test1);
        }

        @Override
        public void onNothingSelected(AdapterView<?> arg0)
        {
            // TODO Auto-generated method stub
        }
    });
}
}

我遇到的问题是每当我尝试从EditText字段获取值并将其存储在应用程序崩溃的两倍时。我一直在寻找解决方案，并且发现如果你先将字段存储在一个字符串中，然后将其转换为一个可以工作的双重......那么它没有。我很确定这是我的错误，虽然我不知道如何解决。我也不想使用按钮。有帮助吗？感谢

Answer 1

试试这个：

如何在结束时使用toString（）：

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希望它有所帮助。

Answer 2

首先，您需要了解这两种类型之间的区别。 double是基本类型，而Double是对象。在您的全局变量中：Double originalBill;

//what editText field is initially stored in
test1 = String.valueOf(e1.getText().toString());  //clear any chance if no string in editText

//test1 string variable gets converted to a double
if(test1 != null)
originalBill = Double.parseDouble(test1);

Answer 3

您可能需要清理从EditText获得的String。使用trim（）删除任何空格（如果有的话）。

        //what editText field is initially stored in
        test1 = e1.getText().toString().trim();

查看String中存储的值

        Log.v("parseDouble", "test1 = " + test1);

确保它不是空的，如果它是＆＃34; 0＆＃34;

        if (test1.isEmpty()) test1 = "0";
        //test1 string variable gets converted to a double
        originalBill = Double.parseDouble(test1);

如何从EditText字段获取值并将其存储在double变量中？

3 个答案: