Android轉換器應用程序崩潰轉換

Question

我已經在android studio中構建了一個轉換器，並且每次按下轉換按鈕時距離部分（活動）都會崩潰。該應用程序表示特定活動已停止工作，並且該應用程序返回到「主要」活動。它沒有在android studio中顯示任何錯誤，我認爲我的問題可能是使用微調框中的int pos，但我不確定。這是完成我的最後一個元素。請幫忙。下面是java之後的xml。

protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main4); 

    spinnerFrom = (Spinner)findViewById(R.id.spinner1); 
    ArrayAdapter<CharSequence> adapterFrom = ArrayAdapter.createFromResource(this, R.array.distance_array, android.R.layout.simple_spinner_item); 
    adapterFrom.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
    spinnerFrom.setAdapter(adapterFrom); 
    spinnerFrom.setOnItemSelectedListener(this); 

    spinnerTo = (Spinner)findViewById(R.id.spinner2); 
    ArrayAdapter<CharSequence> adapterTo = ArrayAdapter.createFromResource(this, R.array.distance_array, android.R.layout.simple_spinner_item); 
    adapterTo.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
    spinnerTo.setAdapter(adapterTo); 
    spinnerTo.setOnItemSelectedListener(this); 

} 
public void convert(View view){ 
    double value = new Double(distance.getText().toString()); 
    from = spinnerFrom.getSelectedItemPosition(); 
    to = spinnerTo.getSelectedItemPosition(); 

    if(from == 0){ 
     if(to == 1) 
      value = UnitConverter.feetToMiles(value); 
     else if (to == 2) 
      value = UnitConverter.feetToMeters(value); 
     else if(to == 3) 
      value = UnitConverter.feetToYards(value); 
     else 
      value = value; 
    }else if(from == 1){ 
     if(to == 0) 
      value = UnitConverter.milesToFeet(value); 
     else if (to == 2) 
      value = UnitConverter.milesToMeters(value); 
     else if(to == 3) 
      value = UnitConverter.milesToYards(value); 
     else 
      value = value; 
    }else if(from == 2){ 
     if(to == 0) 
      value =UnitConverter.metersToFeet(value); 
     else if(to == 1) 
      value = UnitConverter.metersToMiles(value); 
     else if(to == 3) 
      value = UnitConverter.metersToYards(value); 
     else 
      value = value; 
    }else if(from == 3){ 
     if(to == 0) 
      value = UnitConverter.yardsToFeet(value); 
     else if(to == 1) 
      value = UnitConverter.yardsToMiles(value); 
     else if(to == 2) 
      value = UnitConverter.yardsToMeters(value); 
     else 
      value = value; 
    } 
    distance.setText(new Double(value).toString()); 

} 

和XML

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" 
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin" 
android:paddingRight="@dimen/activity_horizontal_margin" 
android:paddingTop="@dimen/activity_vertical_margin" 
android:paddingBottom="@dimen/activity_vertical_margin" 
tools:context="com.example.jacob.myapplication.Main4Activity" 
android:background="@android:color/holo_blue_bright"> 

<TextView 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:textAppearance="?android:attr/textAppearanceLarge" 
    android:text="Distance Converter" 
    android:id="@+id/textViewTitle" 
    android:layout_alignParentTop="true" 
    android:layout_alignParentLeft="true" 
    android:layout_alignParentStart="true" 
    android:layout_marginLeft="92dp" 
    android:layout_marginStart="92dp" /> 

<EditText 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:inputType="numberDecimal" 
    android:ems="10" 
    android:id="@+id/editText" 
    android:layout_below="@+id/textViewTitle" 
    android:layout_centerHorizontal="true" 
    android:hint="Enter Distance" /> 

<Spinner 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/spinner1" 
    android:spinnerMode="dialog" 
    android:clickable="true" 
    android:layout_below="@+id/textViewFrom" 
    android:layout_alignParentLeft="true" 
    android:layout_alignParentStart="true" /> 

<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:textAppearance="?android:attr/textAppearanceLarge" 
    android:text="Convert To:" 
    android:id="@+id/textViewTo" 
    android:layout_below="@+id/spinner1" 
    android:layout_alignParentLeft="true" 
    android:layout_alignParentStart="true" /> 

<Spinner 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/spinner2" 
    android:spinnerMode="dialog" 
    android:layout_below="@+id/textViewTo" 
    android:layout_alignParentLeft="true" 
    android:layout_alignParentStart="true" /> 

<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:textAppearance="?android:attr/textAppearanceLarge" 
    android:text="Convert From" 
    android:id="@+id/textViewFrom" 
    android:layout_below="@+id/editText" 
    android:layout_alignParentLeft="true" 
    android:layout_alignParentStart="true" /> 

<Button 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:text="Convert" 
    android:id="@+id/buttonConvert" 
    android:layout_below="@+id/spinner2" 
    android:layout_centerHorizontal="true" 
    android:onClick="convert" /> 

Answer 1

您沒有使用相同的變量名在這裏

雙值=新的雙（distance.getText（）的toString（））;

什麼是距離，距離是多少？我無法在XML佈局中看到它。

看來你沒有的EditText的名稱更改爲距離，在EditText上的ID名稱是 機器人：ID = 「@ + ID/EDITTEXT」

因此改變距離的名字EDITTEXT