如何从EditText字段获取值并将其存储在双变量中？

Question

这里是我的代码第一：

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，每当我试图让从的EditText字段中的值，并将其存储在双应用程序崩溃。我搜索了解决这个问题的方法，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精度值，那么它不会。我很确定这是我的错误，虽然我没有想法如何解决。我也不想使用按钮。任何帮助？由于

Answer 1

试试这个：

如何在最终用途的toString（）：

tipped.setText(currencyFormat.format(0)).toString(); 

希望它帮助。

Answer 2

首先你需要了解这两种类型的区别。 double是一种原始类型，而Double是一个对象。在您的全局变量：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

您可能需要清理您从EditText上得到字符串。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(); 

看一看什么值存储在字符串

​​

确保它不是空的，如果是使其“0”

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