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我正在为一个android类做一个项目。在这个特定的屏幕上，当它尝试加载时，它会崩溃。我清理了一个空指针异常，但现在我遇到了一个新错误，无法弄清楚。我还没有完成对活动的编码，此时只是读取 xml 文件并尝试让其中一个标签填充微调器......这是该活动的代码：

public class PlayGeoTreasureActivity extends Activity {

    String[] treasureList=null;
    String[] clue1List=null;
    String[] clue2List=null;
    String[] clue3List=null;
    String[] answerList=null;
    String[] locationList=null;
    String[] pointValueList=null;

    XmlPullParserFactory parser;
    XmlPullParser xpp;

    Spinner spinnerTreasures;

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

        spinnerTreasures = (Spinner)findViewById(R.id.treasuresSpinner);

        //get the xml file
        File filename = new File(getFilesDir(), "treasure.xml");

        //check to see if file exists.  If it does, read it.

        try {
        if(filename.exists())
        {       
            readXML(filename);
        }
        else
        {
            Toast.makeText(null, "File not Found", Toast.LENGTH_LONG).show();
        }  
        }catch (FileNotFoundException e) {
            String errorMessage=(e.getMessage()==null)?"Message is Empty":e.getMessage();
            Log.e("GeoTreasureGameLog",errorMessage);
            e.printStackTrace();
        } catch (XmlPullParserException e) {
            String errMessage=(e.getMessage()==null)?"Message is Empty":e.getMessage();
            Log.e("GeoTreasureGameLog",errMessage);
            e.printStackTrace();
        }


    }

    private void readXML(File filename) throws XmlPullParserException, FileNotFoundException {
        // pull parser to read xml file
                    parser = XmlPullParserFactory.newInstance();
                    xpp = parser.newPullParser();

                    // point the xml parser to file
                    xpp.setInput(new FileReader(filename)); 

                    // get start and end tags
                    int eventType = xpp.getEventType();

                    // set current tag
                    String currentTag;

                    // current value of the tag's element
                    String currentElement;

                    //int counter = 0;
                    try{
                    // parse the entire xml file until done
                    while (eventType != XmlPullParser.END_DOCUMENT)
                    { 
                        // look for start tags
                        if(eventType == XmlPullParser.START_TAG)
                        {
                            // get the name of the start tag
                            currentTag = xpp.getName();

                            if (currentTag.equals("TreasureName"))
                            {
                                currentElement = xpp.nextText();
                                treasureList.equals(currentElement);
                            }
                                else if (currentTag.equals("ClueOne"))
                                {
                                    currentElement = xpp.nextText();
                                    clue1List.equals(currentElement);
                                }
                                else if (currentTag.equals("ClueTwo"))
                                {
                                    currentElement = xpp.nextText();
                                    clue2List.equals(currentElement);
                                }
                                else if (currentTag.equals("ClueThree"))
                                {
                                    currentElement = xpp.nextText();
                                    clue3List.equals(currentElement);
                                }
                                else if (currentTag.equals("Answer"))
                                {
                                    currentElement = xpp.nextText();
                                    answerList.equals(currentElement);
                                }
                                else if (currentTag.equals("TreasureLocation"))
                                {
                                    currentElement = xpp.nextText();
                                    locationList.equals(currentElement);
                                }
                                else if (currentTag.equals("PointValue"))
                                {
                                    currentElement = xpp.nextText();
                                    pointValueList.equals(currentElement);
                                }
                        }
                        eventType = xpp.next();
                        }
                    } catch (Exception e)

                    {
                        Log.e("GeoTreasureGameLog", e.getMessage());

                    }
                    Spinner spinner = new Spinner(this);
                    ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item,treasureList);
                    spinner.setAdapter(spinnerArrayAdapter);
    }

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

和错误信息：（新指针异常）

09-17 09:13:24.125: E/AndroidRuntime(3816): FATAL EXCEPTION: main
09-17 09:13:24.125: E/AndroidRuntime(3816): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rasmussen.geotreasuresgame/com.rasmussen.geotreasuresgame.PlayGeoTreasureActivity}: java.lang.NullPointerException: println needs a message
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.os.Looper.loop(Looper.java:137)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.app.ActivityThread.main(ActivityThread.java:5103)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at java.lang.reflect.Method.invokeNative(Native Method)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at java.lang.reflect.Method.invoke(Method.java:525)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at dalvik.system.NativeStart.main(Native Method)
09-17 09:13:24.125: E/AndroidRuntime(3816): Caused by: java.lang.NullPointerException: println needs a message
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.util.Log.println_native(Native Method)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.util.Log.e(Log.java:231)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at com.rasmussen.geotreasuresgame.PlayGeoTreasureActivity.readXML(PlayGeoTreasureActivity.java:137)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at com.rasmussen.geotreasuresgame.PlayGeoTreasureActivity.onCreate(PlayGeoTreasureActivity.java:49)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.app.Activity.performCreate(Activity.java:5133)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
09-17 09:13:24.125: E/AndroidRuntime(3816):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
09-17 09:13:24.125: E/AndroidRuntime(3816):     ... 11 more

这是布局的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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".PlayGeoTreasureActivity" >

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/treasuresSpinner"
        android:layout_alignRight="@+id/treasuresSpinner"
        android:contentDescription="@string/cameraShot"
        android:src="@drawable/ic_launcher" />

    <Spinner
        android:id="@+id/treasuresSpinner"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/imageView1"
        android:layout_centerHorizontal="true" />

    <TextView
        android:id="@+id/guessLabel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/treasuresSpinner"
        android:layout_below="@+id/getClueBtn"
        android:layout_marginTop="48dp"
        android:text="@string/guessLblTxt"
        android:textStyle="bold" />

    <EditText
        android:id="@+id/guessEditText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/guessLabel"
        android:layout_alignLeft="@+id/getClueBtn"
        android:ems="10"
        android:inputType="text" />

    <Button
        android:id="@+id/foundBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/guessEditText"
        android:layout_alignRight="@+id/getClueBtn"
        android:layout_below="@+id/guessEditText"
        android:layout_marginTop="34dp"
        android:text="@string/foundBtnTxt" />

    <TextView
        android:id="@+id/pointsLbl"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/guessLabel"
        android:layout_below="@+id/foundBtn"
        android:layout_marginTop="28dp"
        android:text="@string/pointsEarnedLblTxt"
        android:textStyle="bold" />

    <EditText
        android:id="@+id/pointEarnedEditTxt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/pointsLbl"
        android:layout_alignBottom="@+id/pointsLbl"
        android:layout_alignParentRight="true"
        android:layout_toRightOf="@+id/foundBtn"
        android:ems="10"
        android:inputType="number"
        android:textStyle="bold" />

    <Button
        android:id="@+id/getClueBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/treasuresSpinner"
        android:layout_marginLeft="29dp"
        android:layout_marginTop="28dp"
        android:layout_toRightOf="@+id/guessLabel"
        android:text="@string/getClueBtnTxt" />

</RelativeLayout>

我已经为此苦苦挣扎了3天。所有其他屏幕工作正常。任何帮助将不胜感激。谢谢！！

4

2 回答 2

2 
Log.e("GeoTreasureGameLog", e.getMessage());

getMessage显然返回null。你应该检查一下。

或者更好的是，在调试期间摆脱 try/catch。在这种情况下，您将获得完整的堆栈跟踪（而不是源自 catch 语句内部的堆栈跟踪）。

编辑：您需要通过将 Throws 语句添加到方法签名来将它们冒泡，但您可能会在某些时候卡在那里。相反，您可以将 替换Log.e(...);为e.printStackTrace();. 希望这可以为您提供有关问题所在的更多详细信息。

于 2013-09-17T13:42:00.973 回答
1

在Oracle Throwable 文档 中，据说 .getMessage 可以返回 null。

所以我建议你 e.getMessage()换成e.toString().

于 2013-09-17T14:16:04.863 回答