我正在创建一个具有首选项活动的应用程序，其中 listpreference 条目有问题地分配。此应用程序在我的模拟器上运行良好，但是当我在移动设备中测试我的应用程序时，它显示如下错误
FATAL EXCEPTION: main
java.lang.NullPointerException
at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
at android.widget.AbsListView.obtainView(AbsListView.java:2033)
当我在手机中单击该列表首选项时会出现此问题。这是我的代码
偏好.xml
<PreferenceScreen
xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory
android:title="@string/settings">
<ListPreference
android:key="@string/resolution"
android:title="@string/imageres"
android:summary="@string/summaryres"
android:dialogTitle="@string/resFormat"
/>
</PreferenceCategory>
</PreferenceScreen>
设置.java
package com.example;
import android.database.Cursor;
import android.os.Bundle;
import android.preference.ListPreference;
import android.preference.PreferenceActivity;
public class Settings extends PreferenceActivity {
private SQLiteoperations SQLiteAdapter;
DTO get;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
get = (DTO) getIntent().getExtras().get("obj");
SQLiteAdapter = new SQLiteoperations(this);
SQLiteAdapter.openToWrite();
addPreferencesFromResource(R.xml.preferences);
ListPreference pref = (ListPreference) findPreference("resolution");
pref.setEntries(getEntries());
pref.setEntryValues(getEntries());
System.out.println("after set entries");
System.out.println(get.getDefaultvalues());
pref.setDefaultValue(get.getDefaultvalues());
}
private CharSequence[] getEntries() {
Cursor cursor = SQLiteAdapter.queueAll();
int num = cursor.getCount();
String[] size = new String[num];
System.out.println(cursor.getCount());
if (cursor.moveToFirst()){
int i=0;
do{
size[i]=new String(cursor.getString(1)+"X"+cursor.getString(2));
System.out.println(cursor.getString(1)+"X"+cursor.getString(2));
}while(cursor.moveToNext());
}
cursor.close();
return size;
}
}
camerademo.java
package com.example;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Iterator;
import java.util.List;
import oracle.jdbc.OracleResultSet;
import oracle.sql.BLOB;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.hardware.Camera.Size;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.TableRow.LayoutParams;
import android.widget.TextView;
public class CameraDemo extends Activity {
private final int DIALOG_LICENSE=5;
private final int MENU_SETTINGS=2;
private SharedPreferences settings;
private static final String TAG = "CameraDemo";
Camera camera;
Preview preview;
Button buttonClick,buttonSave,buttonBack;
byte[] image;
private static SQLiteoperations placeData;
final DTO set = new DTO();
String defsize;
// Called when the activity is first created.
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
placeData = new SQLiteoperations(this);
placeData.openToWrite();
preview = new Preview(this);
((FrameLayout) findViewById(R.id.preview)).addView(preview);
buttonSave = (Button) findViewById(R.id.Save);
buttonBack = (Button) findViewById(R.id.back);
buttonBack.setVisibility(View.INVISIBLE);
buttonSave.setVisibility(View.INVISIBLE);
buttonClick = (Button) findViewById(R.id.buttonClick);
settings = PreferenceManager.getDefaultSharedPreferences(this);
SharedPreferences licensPref = getSharedPreferences("PREFS", 0);
boolean licenseShown = licensPref.getBoolean("LicenseShown", false);
if(!licenseShown)
showDialog(DIALOG_LICENSE);
buttonClick.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
preview.camera.takePicture(shutterCallback, rawCallback,
jpegCallback);
buttonClick.setVisibility(View.INVISIBLE);
buttonSave.setVisibility(View.VISIBLE);
buttonBack.setVisibility(View.VISIBLE);
}
});
buttonBack.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
back();
}
});
buttonSave.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
save();
}
});
Log.d(TAG, "onCreate'd");
}
ShutterCallback shutterCallback = new ShutterCallback() {
public void onShutter() {
Log.d(TAG, "onShutter'd");
}
};
// Handles data for raw picture
PictureCallback rawCallback = new PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
Log.d(TAG, "onPictureTaken - raw");
}
};
// Handles data for jpeg picture
PictureCallback jpegCallback = new PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
image = data;
}
};
@Override
protected void onPrepareDialog(int id, Dialog dialog) {
super.onPrepareDialog(id, dialog);
}
@Override
protected Dialog onCreateDialog(int id) {
switch(id){
case DIALOG_LICENSE:
return new AlertDialog.Builder(this)
.setTitle(R.string.welcome)
.setMessage(R.string.welcome_text)
.setPositiveButton(R.string.accept, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
settings = getSharedPreferences("PREFS", 0);
Parameters parameters = preview.camera.getParameters();
Size defaultsize = parameters.getPictureSize();
defsize = (new String(defaultsize.width+"X"+defaultsize.height));
List<Camera.Size> size = parameters.getSupportedPictureSizes();
int num = size.size();
String[] sizeArray = new String[num];
int i=0;
Iterator<Size> si = size.iterator();
while (si.hasNext()) {
Camera.Size sizeObj = (Size) si.next();
sizeArray[i]=new String(sizeObj.width+ "X" +sizeObj.height);
Log.e("size in licence dialog", sizeObj.height+"x"+sizeObj.width);
i++;
placeData.insert(String.valueOf(sizeObj.width),String.valueOf(sizeObj.height));
}
SharedPreferences.Editor editor = settings.edit();
editor.putBoolean("LicenseShown", true);
editor.commit();
}
})
.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
finish();
}
})
.setCancelable(false)
.create();
}
return null;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuItem mi;
mi = menu.add(0, MENU_SETTINGS, 0, R.string.settings);
mi.setIcon(android.R.drawable.ic_menu_preferences);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case MENU_SETTINGS:
set.setDefaultvalues(defsize);
Intent intent = new Intent(getApplicationContext(), Settings.class);
intent.putExtra("obj", set);
startActivity(intent);
return true;
}
return super.onOptionsItemSelected(item);
}
public void back(){
preview.camera.startPreview();
buttonBack.setVisibility(View.INVISIBLE);
buttonSave.setVisibility(View.INVISIBLE);
buttonClick.setVisibility(View.VISIBLE);
}
@Override
public void onDestroy(){
super.onDestroy();
if(preview.camera != null){
preview.camera.stopPreview();
preview.camera = null;
}
}
public void save(){
back();
}
}
有人请告诉我哪里错了吗？