我的Android應用程序意外關機

Question

在得到你們的幫助之後，我建立了一個很棒的應用程序（BMI計算器）。在添加一個搜索欄並清除代碼中的所有錯誤之後，當我測試時，應用程序不會啓動，顯示消息「App shutdown unexpectedlyly」。

seekbars是一個可選方法，用於更改textedit字段中的值。

這裏的MainActiviy.java

package com.example.calculadorimc; 

import android.app.Activity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.View; 
import android.widget.EditText; 
import android.widget.RadioGroup; 
import android.widget.SeekBar; 
import android.widget.SeekBar.OnSeekBarChangeListener; 
import android.widget.TextView; 

public class MainActivity extends Activity { 
    private RadioGroup rgsexo; 
    EditText editPeso; 
    EditText editAltura; 
    TextView imcView; 
    SeekBar alterarAltura; 
    SeekBar alterarPeso; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 

    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    alterarAltura.setOnSeekBarChangeListener(alteraralturaListener); 
    editPeso = (EditText)findViewById(R.id.editPeso); 
    editAltura = (EditText)findViewById(R.id.editAltura); 
    imcView = (TextView)findViewById(R.id.imcView); 
    alterarAltura = (SeekBar)findViewById(R.id.alterarAltura); 
    alterarPeso = (SeekBar)findViewById(R.id.alterarPeso); 
} 

private OnSeekBarChangeListener alteraralturaListener = new OnSeekBarChangeListener() { 

    @Override 
    public void onProgressChanged(SeekBar seekBar, int progress, 
    boolean fromUser) { 
     // TODO Auto-generated method stub 
     // Calcula o novo valor do TIP 

     double setAltura = (alterarAltura.getProgress()) * .01d; 
     // mostra na caixa o valor novo 
     editAltura.setText(String.format("%.02f", setAltura).replace(',', '.')); 
    } 

    @Override 
    public void onStopTrackingTouch(SeekBar seekBar) { 

    } 

    @Override 
    public void onStartTrackingTouch(SeekBar seekBar) { 

    } 
}; 
public void calculateClickHandler(View view) { 

    // make sure we handle the click of the calculator button 

    if (view.getId() == R.id.botaoCalcular) { 

    // get the users values from the widget references 

    float peso = Float.parseFloat(editPeso.getText().toString()); 
    float altura = Float.parseFloat(editAltura.getText().toString()); 

    // calculate the bmi value 

    float imcValue = calcularIMC(peso, altura); 

    // interpret the meaning of the bmi value 
    String imcInterpretation = interpretIMC(imcValue); 

    // now set the value in the result text 

    imcView.setText(imcValue + "-" + imcInterpretation); 
    } 
    } 
    // the formula to calculate the BMI index 

    // check for http://en.wikipedia.org/wiki/Body_mass_index 
    private float calcularIMC (float peso, float altura) { 

    return (float) (peso/(altura * altura)); 
    } 

    // interpret what BMI means 
    private String interpretIMC(float imcValue) {   

     rgsexo = (RadioGroup)findViewById(R.id.rgSexo); 
     int selectedId = rgsexo.getCheckedRadioButtonId(); // get the id 

     switch (selectedId) // switch on the button selected 
     { 
      case R.id.radioMasc: 
       if (imcValue < 20) { 
        return "Abaixo do Peso"; 
        } else if (imcValue < 24.9) { 

        return "Peso Normal"; 
        } else if (imcValue < 29.9) { 

        return "Acima do Peso"; 
        } else if (imcValue < 39.9) { 

        return "Obesidade Moderada"; 
        } else { 
        return "Obesidade Mórbida"; 
        } 
      case R.id.radioFem: 
       if (imcValue < 19) { 
        return "Abaixo do Peso"; 
        } else if (imcValue < 23.9) { 

        return "Peso Normal"; 
        } else if (imcValue < 28.9) { 

        return "Acima do Peso"; 
        } else if (imcValue < 38.9) { 

        return "Obesidade Moderada"; 
        } else { 
        return "Obesidade Mórbida"; 
        } 
     } 
    return null; 
    } 
@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.main, menu); 
    return true; 
} 

} 

而且Activitymain.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="wrap_content" 
android:orientation="vertical" 
tools:context=".MainActivity" > 

<RadioGroup 
    android:id="@+id/rgSexo" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:orientation="horizontal" > 

    <RadioButton 
     android:id="@+id/radioMasc" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:checked="true" 
     android:text="@string/radioMasc" /> 

    <RadioButton 
     android:id="@+id/radioFem" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="@string/radioFem" /> 
</RadioGroup> 

<TextView 
    android:id="@+id/alturaView" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="@string/alturaView" /> 

<EditText 
    android:id="@+id/editAltura" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:ems="5" 
    android:inputType="numberDecimal" 
    android:text="@string/editAltura" > 

    <requestFocus /> 
</EditText> 

<SeekBar 
    android:id="@+id/alterarAltura" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:max="3" /> 

<TextView 
    android:id="@+id/pesoView" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="@string/pesoView" /> 

<EditText 
    android:id="@+id/editPeso" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:ems="5" 
    android:inputType="number" 
    android:text="@string/editPeso" /> 

<SeekBar 
    android:id="@+id/alterarPeso" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:max="600" /> 

<View 
    android:layout_width="fill_parent" 
    android:layout_height="2dip" 
    android:layout_marginBottom="5dip" 
    android:layout_marginTop="5dip" 
    android:background="#111111" /> 

<Button 
    android:id="@+id/botaoCalcular" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:onClick="calculateClickHandler" 
    android:text="@string/botaoCalcular" /> 

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

感謝您的支持。

P.S.我是一個總的N00B

logcat的文件

03-04 21:18:38.492: D/AndroidRuntime(279): Shutting down 

VM 
03-04 21:18:38.492: W/dalvikvm(279): threadid=1: thread 

exiting with uncaught exception (group=0x4001d800) 
03-04 21:18:38.542: E/AndroidRuntime(279): FATAL 

EXCEPTION: main 
03-04 21:18:38.542: E/AndroidRuntime(279): 

java.lang.RuntimeException: Unable to start activity 

ComponentInfo 

{com.example.calculadorimc/com.example.calculadorimc.Main 

Activity}: java.lang.NullPointerException 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

android.app.ActivityThread.performLaunchActivity 

(ActivityThread.java:2663) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

android.app.ActivityThread.handleLaunchActivity 

(ActivityThread.java:2679) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

android.app.ActivityThread.access$2300 

(ActivityThread.java:125) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

android.app.ActivityThread$H.handleMessage 

(ActivityThread.java:2033) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

android.os.Handler.dispatchMessage(Handler.java:99) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

android.os.Looper.loop(Looper.java:123) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

android.app.ActivityThread.main(ActivityThread.java:4627) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

java.lang.reflect.Method.invokeNative(Native Method) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

java.lang.reflect.Method.invoke(Method.java:521) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

com.android.internal.os.ZygoteInit 

$MethodAndArgsCaller.run(ZygoteInit.java:868) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

com.android.internal.os.ZygoteInit.main 

(ZygoteInit.java:626) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

dalvik.system.NativeStart.main(Native Method) 
03-04 21:18:38.542: E/AndroidRuntime(279): Caused by: 

java.lang.NullPointerException 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

com.example.calculadorimc.MainActivity.onCreate 

(MainActivity.java:27) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

android.app.Instrumentation.callActivityOnCreate 

(Instrumentation.java:1047) 
03-04 21:18:38.542: E/AndroidRuntime(279): at 

android.app.ActivityThread.performLaunchActivity 

(ActivityThread.java:2627) 
03-04 21:18:38.542: E/AndroidRuntime(279): ... 11 

more 
03-04 21:18:44.231: I/Process(279): Sending signal. PID: 

279 SIG: 9 
03-04 21:18:48.231: D/AndroidRuntime(286): Shutting down 

VM 
03-04 21:18:48.231: W/dalvikvm(286): threadid=1: thread 

exiting with uncaught exception (group=0x4001d800) 
03-04 21:18:48.272: E/AndroidRuntime(286): FATAL 

EXCEPTION: main 
03-04 21:18:48.272: E/AndroidRuntime(286): 

java.lang.RuntimeException: Unable to start activity 

ComponentInfo 

{com.example.calculadorimc/com.example.calculadorimc.Main 

Activity}: java.lang.NullPointerException 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

android.app.ActivityThread.performLaunchActivity 

(ActivityThread.java:2663) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

android.app.ActivityThread.handleLaunchActivity 

(ActivityThread.java:2679) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

android.app.ActivityThread.access$2300 

(ActivityThread.java:125) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

android.app.ActivityThread$H.handleMessage 

(ActivityThread.java:2033) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

android.os.Handler.dispatchMessage(Handler.java:99) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

android.os.Looper.loop(Looper.java:123) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

android.app.ActivityThread.main(ActivityThread.java:4627) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

java.lang.reflect.Method.invokeNative(Native Method) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

java.lang.reflect.Method.invoke(Method.java:521) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

com.android.internal.os.ZygoteInit 

$MethodAndArgsCaller.run(ZygoteInit.java:868) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

com.android.internal.os.ZygoteInit.main 

(ZygoteInit.java:626) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

dalvik.system.NativeStart.main(Native Method) 
03-04 21:18:48.272: E/AndroidRuntime(286): Caused by: 

java.lang.NullPointerException 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

com.example.calculadorimc.MainActivity.onCreate 

(MainActivity.java:27) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

android.app.Instrumentation.callActivityOnCreate 

(Instrumentation.java:1047) 
03-04 21:18:48.272: E/AndroidRuntime(286): at 

android.app.ActivityThread.performLaunchActivity 

(ActivityThread.java:2627) 
03-04 21:18:48.272: E/AndroidRuntime(286): ... 11 

more 
03-04 21:18:52.073: I/Process(286): Sending signal. PID: 

286 SIG: 9 

Answer 1

初始化alterarAltura與findViewById()調用它的方法了。

Answer 2

你需要可變分配現場後打電話到.setOnSeek...，否則alterarAltura將null和操作上null結果NullPointerException

例子：

editPeso = (EditText)findViewById(R.id.editPeso); 
    editAltura = (EditText)findViewById(R.id.editAltura); 
    imcView = (TextView)findViewById(R.id.imcView); 
    alterarAltura = (SeekBar)findViewById(R.id.alterarAltura); 
    alterarPeso = (SeekBar)findViewById(R.id.alterarPeso); 
    alterarAltura.setOnSeekBarChangeListener(alteraralturaListener);