我正在开发一个应用程序来显示 android 中形状文件的记录数。但是由于以下错误，它给出了空指针异常
07-23 15:16:32.598: W/dalvikvm(2844): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
07-23 15:16:32.677: E/AndroidRuntime(2844): FATAL EXCEPTION: main
07-23 15:16:32.677: E/AndroidRuntime(2844): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.android.skeletonapp/com.example.android.skeletonapp.SkeletonActivity}: java.lang.InstantiationException: com.example.android.skeletonapp.SkeletonActivity
07-23 15:16:32.677: E/AndroidRuntime(2844): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585)
07-23 15:16:32.677: E/AndroidRuntime(2844): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
07-23 15:16:32.677: E/AndroidRuntime(2844): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
07-23 15:16:32.677: E/AndroidRuntime(2844): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
07-23 15:16:32.677: E/AndroidRuntime(2844): at android.os.Handler.dispatchMessage(Handler.java:99)
07-23 15:16:32.677: E/AndroidRuntime(2844): at android.os.Looper.loop(Looper.java:123)
07-23 15:16:32.677: E/AndroidRuntime(2844): at android.app.ActivityThread.main(ActivityThread.java:4627)
07-23 15:16:32.677: E/AndroidRuntime(2844): at java.lang.reflect.Method.invokeNative(Native Method)
07-23 15:16:32.677: E/AndroidRuntime(2844): at java.lang.reflect.Method.invoke(Method.java:521)
07-23 15:16:32.677: E/AndroidRuntime(2844): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
07-23 15:16:32.677: E/AndroidRuntime(2844): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
07-23 15:16:32.677: E/AndroidRuntime(2844): at dalvik.system.NativeStart.main(Native Method)
07-23 15:16:32.677: E/AndroidRuntime(2844): Caused by: java.lang.InstantiationException: com.example.android.skeletonapp.SkeletonActivity
07-23 15:16:32.677: E/AndroidRuntime(2844): at java.lang.Class.newInstanceImpl(Native Method)
07-23 15:16:32.677: E/AndroidRuntime(2844): at java.lang.Class.newInstance(Class.java:1429)
07-23 15:16:32.677: E/AndroidRuntime(2844): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
07-23 15:16:32.677: E/AndroidRuntime(2844): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577)
07-23 15:16:32.677: E/AndroidRuntime(2844): ... 11 more
SkeletonActivity.java 是
public class SkeletonActivity extends Activity {
static final private int BACK_ID = Menu.FIRST;
static final private int CLEAR_ID = Menu.FIRST + 1;
private static String SHP_PATH = Environment.getDataDirectory().getAbsolutePath() + "/data/com.shapes/places";
private static String SHP_NAME = "popplaces.shp";
private EditText mEditor;
private final Context myContext;
public SkeletonActivity(Context context) {
this.myContext=context;
}
/** Called with the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
int recordCount = 0;
// Inflate our UI from its XML layout description.
setContentView(R.layout.skeleton_activity);
// Find the text editor view inside the layout, because we
// want to do various programmatic things with it.
mEditor = (EditText) findViewById(R.id.editor);
// Hook up button presses to the appropriate event handler.
((Button) findViewById(R.id.back)).setOnClickListener(mBackListener);
((Button) findViewById(R.id.clear)).setOnClickListener(mClearListener);
mEditor.setText(getText(R.string.main_label));
try {
//File path = Environment.getExternalStoragePublicDirectory(
// Environment.DIRECTORY_PICTURES);
//path = Environment.getDataDirectory().getAbsolutePath();
//path.mkdirs();
//shpFile = path.getPath().toString();
copyFromZipFile();
String shpFile = Environment.getDataDirectory().getAbsolutePath()+"/data/com.shapes/places/popplaces.shp";
ShapeReader shR = new ShapeReader(shpFile, true);
recordCount = shR.getCount(0);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
mEditor.setText("Record Count == " + recordCount);
}
/**
* Called when the activity is about to start interacting with the user.
*/
@Override
protected void onResume() {
super.onResume();
}
/**
* Called when your activity's options menu needs to be created.
*/
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
// We are going to create two menus. Note that we assign them
// unique integer IDs, labels from our string resources, and
// given them shortcuts.
menu.add(0, BACK_ID, 0, R.string.back).setShortcut('0', 'b');
menu.add(0, CLEAR_ID, 0, R.string.clear).setShortcut('1', 'c');
return true;
}
/**
* Called right before your activity's option menu is displayed.
*/
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
super.onPrepareOptionsMenu(menu);
// Before showing the menu, we need to decide whether the clear
// item is enabled depending on whether there is text to clear.
menu.findItem(CLEAR_ID).setVisible(mEditor.getText().length() > 0);
return true;
}
/**
* Called when a menu item is selected.
*/
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case BACK_ID:
finish();
return true;
case CLEAR_ID:
mEditor.setText("");
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A call-back for when the user presses the back button.
*/
OnClickListener mBackListener = new OnClickListener() {
public void onClick(View v) {
finish();
}
};
/**
* A call-back for when the user presses the clear button.
*/
OnClickListener mClearListener = new OnClickListener() {
public void onClick(View v) {
mEditor.setText("");
}
};
public void copyFromZipFile() throws IOException{
InputStream is = myContext.getResources().openRawResource(R.raw.shape);
// Path to the just created empty db
File outFile = new File(SHP_PATH ,SHP_NAME);
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFile.getAbsolutePath());
ZipInputStream zis = new ZipInputStream(new BufferedInputStream(is));
try {
ZipEntry ze = null;
while ((ze = zis.getNextEntry()) != null) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[24 * 1024];
int count;
while ((count = zis.read(buffer)) != -1) {
baos.write(buffer, 0, count);
//Log.d("", buffer.toString());
baos.writeTo(myOutput);
baos.reset();
}
baos.writeTo(myOutput);
}
}
catch (IOException e) {}
zis.close();
myOutput.flush();
myOutput.close();
is.close();
}
}
Manifest.xml 是
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.skeletonapp">
<application android:label="@string/skeleton_app">
<activity android:name="SkeletonActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
请帮我解决这个问题。谢谢。