簡單的單位轉換器，但在午餐時崩潰

編譯完美，但在午餐時崩潰... LogCat說：「無法啓動活動ComponentInfo ........ 這裏是Main.xml，Activity的代碼。 Java和logcat的......簡單的單位轉換器，但在午餐時崩潰

Main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="fill_parent" 
android:layout_height="fill_parent" 
android:gravity="left|right" 
android:orientation="vertical" 
android:background="#66FFFF" >  

<FrameLayout 
    android:id="@+id/frameLayout2" 
    android:layout_width="match_parent" 
    android:layout_height="20dp" > 
</FrameLayout> 

<TextView 
    android:id="@+id/UnitText" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="@string/UnitText" 
    android:textColor="@android:color/black" 
    android:textAppearance="?android:attr/textAppearanceLarge" /> 

<Spinner 
    android:id="@+id/Spinner1" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:prompt="@string/UnitPrompt"/> 

<FrameLayout 
    android:id="@+id/frameLayout3" 
    android:layout_width="match_parent" 
    android:layout_height="20dp" > 
</FrameLayout> 


<LinearLayout 
    android:id="@+id/linearLayout1" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:gravity="right" 
    android:orientation="vertical" > 


    <Button 
     android:onClick="converter" 
     android:id="@+id/ConvertButton" 
     android:layout_width="131dp" 
     android:layout_height="wrap_content" 
     android:text="@string/ConvertText" /> 

</LinearLayout> 

<FrameLayout 
    android:id="@+id/frameLayout1" 
    android:layout_width="match_parent" 
    android:layout_height="30dip" > 
</FrameLayout> 

<TableLayout 
    android:id="@+id/tableLayout1" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" > 

    <TableRow 
     android:id="@+id/tableRow1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" > 

     <EditText 
      android:id="@+id/BeforeBox" 
      android:layout_width="250dp" 
      android:layout_height="wrap_content" 
      android:inputType="numberDecimal" /> 

     <TextView 
      android:id="@+id/BeforeText" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="@string/BeforeText" 
      android:textColor="@android:color/black" 
      android:textAppearance="?android:attr/textAppearanceLarge" /> 
    </TableRow> 

    <TableRow 
     android:id="@+id/tableRow2" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" > 

     <EditText 
      android:id="@+id/AfterBox" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:inputType="numberDecimal" /> 

     <TextView 
      android:id="@+id/AfterText" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="@string/AfterText" 
      android:textColor="@android:color/black" 
      android:textAppearance="?android:attr/textAppearanceLarge" /> 
    </TableRow> 
</TableLayout>

Activity.Java 
package arirang.unit.converter; 

import java.text.DecimalFormat; 

import android.app.Activity; 
import android.os.Bundle; 
import android.widget.ArrayAdapter; 
import android.widget.Spinner; 
import android.widget.EditText; 
import android.widget.TextView; 


public class BasicUnitConverterActivity extends Activity { 

EditText val3; 
String val2; 
int val1; 
String forResult; 
Spinner Type; 


/** Called when the activity is first created. */ 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 

    Spinner spinner1 = (Spinner) findViewById(R.id.Spinner1); 
    ArrayAdapter adapter1 = ArrayAdapter.createFromResource(
      this, R.array.UnitList, android.R.layout.simple_spinner_item); 
    adapter1.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
    spinner1.setAdapter(adapter1); 

    EditText val3 = (EditText)findViewById(R.id.BeforeBox); 
    String val2 = val3.getText().toString(); 
    val1 = Integer.parseInt(val2); 


    forResult = changeFormat(converter(val1)); 

    TextView AfterBox = (TextView)findViewById(R.id.AfterBox); 
    AfterBox.setText(forResult); 

} 

private String changeFormat(Double dbResult) { 
    String result; 

    DecimalFormat format = new DecimalFormat("##.##"); 
    result = format.format(dbResult); 
    return result; 
} 



public double converter(double val1) { 
    Type = (Spinner)findViewById(R.id.Spinner1); 
    double dbResult = 0; 

    if(Type.getSelectedItem().toString().equals("meter to inch")) 
    { 
     dbResult = val1 * 39.3700787 ; 
    } 

    else if(Type.getSelectedItem().toString().equals("meter to feet")) 
    { 
     dbResult = val1 * 3.2808399; 
    } 

    else if(Type.getSelectedItem().toString().equals("feet to inch")) 
    { 
     dbResult = val1 * 12; 
    } 

    else if(Type.getSelectedItem().toString().equals("feet to meter")) 
    { 
     dbResult = val1/3.2808399; 
    } 

    else if(Type.getSelectedItem().toString().equals("inch to meter")) 
    { 
     dbResult = val1/39.3700787 ; 
    } 

    else if(Type.getSelectedItem().toString().equals("inch to feet")) 
    { 
     dbResult = val1/12; 
    } 

    else if(Type.getSelectedItem().toString().equals("kilogram to pound")) 
    { 
     dbResult = val1 * 2.20462262; 
    } 

    else if(Type.getSelectedItem().toString().equals("pound to kilogram")) 
    { 
     dbResult = val1/2.20462262; 
    } 

    else if(Type.getSelectedItem().toString().equals("Fahrenheit to Celsius")) 
    { 
     dbResult=(val1 - 32)/(5/9); 
    } 

    else if(Type.getSelectedItem().toString().equals("Celsius to Fahrenheit")) 
    { 
     dbResult = (9/5) * val1 + 32; 
    } 

    return dbResult; 
} 
}

這是logcat的日誌

Logcat log 
Shutting down VM 

threadid=1: thread exiting with uncaught exception (group=0x40015560) 

FATAL EXCEPTION: main 
java.lang.RuntimeException: Unable to start activity ComponentInfo{arirang.unit.converter/arirang.unit.converter.BasicUnitConverterActivity}: java.lang.NumberFormatException: unable to parse '' as integer 

E/AndroidRuntime(330): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 

E/AndroidRuntime(330): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 

E/AndroidRuntime(330): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 

E/AndroidRuntime(330): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 

E/AndroidRuntime(330): at android.os.Handler.dispatchMessage(Handler.java:99) 

E/AndroidRuntime(330): at android.os.Looper.loop(Looper.java:123) 

E/AndroidRuntime(330): at android.app.ActivityThread.main(ActivityThread.java:3683) 

E/AndroidRuntime(330): at java.lang.reflect.Method.invokeNative(Native Method) 

E/AndroidRuntime(330): at java.lang.reflect.Method.invoke(Method.java:507) 

E/AndroidRuntime(330): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 

E/AndroidRuntime(330): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 

E/AndroidRuntime(330): at dalvik.system.NativeStart.main(Native Method) 

E/AndroidRuntime(330): Caused by: java.lang.NumberFormatException: unable to parse '' as integer 

E/AndroidRuntime(330): at java.lang.Integer.parseInt(Integer.java:362) 

E/AndroidRuntime(330): at java.lang.Integer.parseInt(Integer.java:332) 

E/AndroidRuntime(330): at arirang.unit.converter.BasicUnitConverterActivity.onCreate(BasicUnitConverterActivity.java:37) 

E/AndroidRuntime(330): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 

E/AndroidRuntime(330): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 

E/AndroidRuntime(330): ... 11 more

說真的，非常感謝你幫助我，即使這些代碼不短... ^^

來源

2012-02-08 user1193653

問題是當應用程序加載onCreate（）被調用，並且文本框中沒有任何內容，因此當您調用val3 .getText（）。toString（）沒有什麼。我建議

val3.addTextChangedListener(new TextWatcher(){ 
    public void afterTextChanged(Editable s) { 
     val2 = val3.getText().toString() 
    } 
    public void beforeTextChanged(CharSequence s, int start, int count, int after){} 
    public void onTextChanged(CharSequence s, int start, int before, int count){} 
});

所以當你輸入的值，它會抓住它後，你完成輸入它。

來源

2012-02-08 02:32:07 JakeWilson801

看起來像是在創建活動時立即執行轉換，而不是在有人點擊轉換按鈕時執行轉換。您已在佈局中定義的onClick監聽器，但你不使用它...嘗試添加該功能：

public void converter(View view) { 
    EditText val3 = (EditText)findViewById(R.id.BeforeBox); 
    String val2 = val3.getText().toString(); 
    if(val2.length() > 0) { 
     val1 = Integer.parseInt(val2); 


     forResult = changeFormat(converter(val1)); 

     TextView AfterBox = (TextView)findViewById(R.id.AfterBox); 
     AfterBox.setText(forResult); 
    } 
}

，改變你的onCreate()這樣：

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 

    Spinner spinner1 = (Spinner) findViewById(R.id.Spinner1); 
    ArrayAdapter adapter1 = ArrayAdapter.createFromResource(
     this, R.array.UnitList, android.R.layout.simple_spinner_item); 
    adapter1.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
    spinner1.setAdapter(adapter1); 
}

來源

2012-02-08 02:37:04

簡單的單位轉換器，但在午餐時崩潰

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