我的问题在我的 onItemClickListener 方法中。当它获得分配“selectedEmail”的行时。logcat 声称没有名为 Email 的列，所以我不确定实际问题出在哪里。
ContactsMenu 类的代码
package com.emailandcontactmanager;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;
public class ContactsMenu extends Activity {
ListView listView;
public static final String fields[] = { DatabaseSetup.colName};
Cursor cursor;
public static String name;
public static String email;
public static String phone1;
public static String phone2;
public static String address;
public static String notes;
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.managecontacts);
listView = (ListView) findViewById(R.id.lstContacts);
DatabaseSetup.init(this);
Button btnAddItem = (Button) findViewById(R.id.btnAddContact);
btnAddItem.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent addItem = new Intent(v.getContext(), AddContact.class);
startActivity(addItem);
}
});
listView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> listView, View view,
int position, long id) {
// Get the cursor, positioned to the corresponding row in the result set
//cursor = DatabaseSetup.getContactData();
Cursor cursor = (Cursor) listView.getItemAtPosition(position);
//change cursor
String selectedName = cursor.getString(cursor.getColumnIndexOrThrow("Name"));
String selectedEmail = cursor.getString(cursor.getColumnIndexOrThrow("Email"));
String selectedPhone1 = cursor.getString(cursor.getColumnIndexOrThrow("Phone1"));
String selectedPhone2 = cursor.getString(cursor.getColumnIndexOrThrow("Phone2"));
String selectedAddress = cursor.getString(cursor.getColumnIndexOrThrow("Address"));
String selectedNotes = cursor.getString(cursor.getColumnIndexOrThrow("Notes"));
setName(selectedName);
setName(selectedEmail);
setName(selectedPhone1);
setName(selectedPhone2);
setName(selectedAddress);
setName(selectedNotes);
Intent viewItem = new Intent(view.getContext(), ViewContact.class);
startActivity(viewItem);
}
});
}
@Override
protected void onPause() {
listView.setAdapter(null);
cursor.close();
DatabaseSetup.deactivate();
super.onPause();
}
@Override
protected void onResume() {
super.onResume();
DatabaseSetup.init(this);
//Updated
cursor = DatabaseSetup.getContactData();
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, R.layout.row, cursor, fields, new int[] {R.id.item_text});
listView.setAdapter(adapter);
}
public void setName(String selectedName) {
name = selectedName;
}
public void setEmail(String selectedEmail) {
email = selectedEmail;
}
public void setPhone1(String selectedPhone1) {
phone1 = selectedPhone1;
}
public void setPhone2(String selectedPhone2) {
phone2 = selectedPhone2;
}
public void setAddress(String selectedAddress) {
address = selectedAddress;
}
public void setNotes(String selectedNotes) {
notes = selectedNotes;
}
public static String getName() {
String itemName = name;
return itemName;
}
public static String getEmail() {
String itemEmail = email;
return itemEmail;
}
public static String getPhone1() {
String itemPhone1 = phone1;
return itemPhone1;
}
public static String getPhone2() {
String itemPhone2 = phone2;
return itemPhone2;
}
public static String getAddress() {
String itemAddress = address;
return itemAddress;
}
public static String getNotes() {
String itemNotes = notes;
return itemNotes;
}
////////////////MENU////////////////////////////////////////////////////////////////////////////////
DialogInterface.OnClickListener dialogClickListener = new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
switch (which){
case DialogInterface.BUTTON_POSITIVE:
finish();
break;
case DialogInterface.BUTTON_NEGATIVE:
//Nothing happens on No button click, and the menu closes
break;
}
}
};
@Override
public boolean onCreateOptionsMenu(Menu mainmenu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.mainmenu, mainmenu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
final CharSequence[] items = {"Contacts list", "Add Contact"};
switch (item.getItemId()) {
case R.id.help: AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Select a function to revice information about it.");
builder.setItems(items, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int selected) {
switch(selected){
case 0:
Toast.makeText(getApplicationContext(),
"Allows you to view the selected item and make editations to it or delete it.",
Toast.LENGTH_LONG).show();
break;
case 1:
Toast.makeText(getApplicationContext(),
"Allows you to add a new contact by bringing up a screen where the nececary information can be entered.",
Toast.LENGTH_LONG).show();
}
}
});
builder.show();
break;
case R.id.back: AlertDialog.Builder builderBack = new AlertDialog.Builder(this);
builderBack.setMessage("Are you sure?").setPositiveButton("Yes", dialogClickListener)
.setNegativeButton("No", dialogClickListener).show();
break;
}
return true;
}
}
DatabaseSetup 类的代码
package com.emailandcontactmanager;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
/*
* usage:
* DatabaseSetup.init(egActivityOrContext);
* DatabaseSetup.createEntry() or DatabaseSetup.getContactNames() or DatabaseSetup.getDb()
* DatabaseSetup.deactivate() then job done
*/
class DatabaseSetup extends SQLiteOpenHelper {
static DatabaseSetup instance = null;
static SQLiteDatabase db = null;
public static void init(Context context) {
if (null == instance) {
instance = new DatabaseSetup(context);
}
}
public static SQLiteDatabase getDb() {
if (null == db) {
db = instance.getWritableDatabase();
}
return db;
}
public static void deactivate() {
if (null != db && db.isOpen()) {
db.close();
}
db = null;
instance = null;
}
public static long createEntry(String name, String mail, String phone1,
String phone2, String address, String notes) {
ContentValues cv = new ContentValues();
cv.put(colName, name);
cv.put(colMail, mail);
cv.put(colPhone1, phone1);
cv.put(colPhone2, phone2);
cv.put(colAddress, address);
cv.put(colNotes, notes);
return getDb().insert(contactsTable, null, cv);
}
/* Old
public static Cursor getContactNames() {
// TODO Auto-generated method stub
String[] columns = new String[] {"_id", colName };
return getDb().query(contactsTable, columns, null, null, null, null,
null);
}
*/
public static Cursor getContactData(){
String[] columns = new String[] {"_id", colName, colMail, colPhone1, colPhone2, colAddress, colNotes };
return getDb().query(contactsTable, columns, null, null, null, null,
null);
}
DatabaseSetup(Context context) {
super(context, dbName, null, dbVersion);
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("CREATE TABLE IF NOT EXISTS " + contactsTable
+ " (_id integer primary key autoincrement, " + colName
+ " TEXT NOT NULL, " + colMail + " TEXT NOT NULL, " + colPhone1
+ " TEXT NOT NULL, " + colPhone2 + " TEXT NOT NULL, "
+ colAddress + " TEXT NOT NULL, " + colNotes
+ " TEXT NOT NULL)");
db.execSQL("CREATE TABLE IF NOT EXISTS " + templatesTable
+ " (_id integer primary key autoincrement, " + colSubject
+ " TEXT NOT NULL, " + colBody + " TEXT NOT NULL)");
db.execSQL("CREATE TABLE IF NOT EXISTS " + tagsTable
+ " (_id integer primary key autoincrement, " + colTagName
+ " TEXT NOT NULL, " + colContact + " TEXT NOT NULL)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + contactsTable);
db.execSQL("DROP TABLE IF EXISTS " + templatesTable);
db.execSQL("DROP TABLE IF EXISTS " + tagsTable);
onCreate(db);
}
static final String dbName = "DB";
static final int dbVersion = 1;
static final String contactsTable = "Contacts";
static final String colName = "Name";
static final String colMail = "Email";
static final String colPhone1 = "Phone1";
static final String colPhone2 = "Phone2";
static final String colAddress = "Address";
static final String colNotes = "Notes";
static final String templatesTable = "Templates";
static final String colSubject = "Subject";
static final String colBody = "Body";
static final String tagsTable = "Tags";
static final String colTagName = "Name";
static final String colContact = "Contact";
}
ViewContact 类的代码
package com.emailandcontactmanager;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class ViewContact extends Activity {
EditText nameField, mailield, phoneField1, phoneField2, addressField, notesField;
String name, mail, phone1, phone2, address, notes;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewcontact);
nameField = (EditText) findViewById(R.id.txtName);
mailield = (EditText) findViewById(R.id.txtMail);
phoneField1 = (EditText) findViewById(R.id.txtPhone1);
phoneField2 = (EditText) findViewById(R.id.txtPhone2);
addressField = (EditText) findViewById(R.id.txtAddress);
notesField = (EditText) findViewById(R.id.txtNotes);
name = ContactsMenu.getName();
mail = ContactsMenu.getEmail();
phone1 =ContactsMenu.getPhone1();
phone2 =ContactsMenu.getPhone2();
address =ContactsMenu.getAddress();
notes =ContactsMenu.getNotes();
nameField.setText(name);
mailield.setText(mail);
phoneField1.setText(phone1);
phoneField2.setText(phone2);
addressField.setText(address);
notesField.setText(notes);
Button btnEditContact = (Button) findViewById(R.id.btnEditContact);
btnEditContact.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
editContact();
}
});
Button btnDeleteContact = (Button) findViewById(R.id.btnEditContact);
btnDeleteContact.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
deleteContact();
}
});
Button btnEditTags = (Button) findViewById(R.id.btnEditContact);
btnEditTags.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent editTags = new Intent(v.getContext(), EditContactTags.class);
startActivity(editTags);
}
});
}
public void editContact(){
}
public void deleteContact(){
}
public void setValues(){
}
}
日志输出
10-16 13:37:12.824: D/gralloc_goldfish(869): Emulator without GPU emulation detected.
10-16 13:37:20.553: D/AndroidRuntime(869): Shutting down VM
10-16 13:37:20.553: W/dalvikvm(869): threadid=1: thread exiting with uncaught exception (group=0x409961f8)
10-16 13:37:20.603: E/AndroidRuntime(869): FATAL EXCEPTION: main
10-16 13:37:20.603: E/AndroidRuntime(869): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.emailandcontactmanager/com.emailandcontactmanager.ViewContact}: java.lang.NullPointerException
10-16 13:37:20.603: E/AndroidRuntime(869): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1879)
10-16 13:37:20.603: E/AndroidRuntime(869): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
10-16 13:37:20.603: E/AndroidRuntime(869): at android.app.ActivityThread.access$600(ActivityThread.java:122)
10-16 13:37:20.603: E/AndroidRuntime(869): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
10-16 13:37:20.603: E/AndroidRuntime(869): at android.os.Handler.dispatchMessage(Handler.java:99)
10-16 13:37:20.603: E/AndroidRuntime(869): at android.os.Looper.loop(Looper.java:137)
10-16 13:37:20.603: E/AndroidRuntime(869): at android.app.ActivityThread.main(ActivityThread.java:4340)
10-16 13:37:20.603: E/AndroidRuntime(869): at java.lang.reflect.Method.invokeNative(Native Method)
10-16 13:37:20.603: E/AndroidRuntime(869): at java.lang.reflect.Method.invoke(Method.java:511)
10-16 13:37:20.603: E/AndroidRuntime(869): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
10-16 13:37:20.603: E/AndroidRuntime(869): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
10-16 13:37:20.603: E/AndroidRuntime(869): at dalvik.system.NativeStart.main(Native Method)
10-16 13:37:20.603: E/AndroidRuntime(869): Caused by: java.lang.NullPointerException
10-16 13:37:20.603: E/AndroidRuntime(869): at android.app.Activity.findViewById(Activity.java:1794)
10-16 13:37:20.603: E/AndroidRuntime(869): at com.emailandcontactmanager.ViewContact.<init>(ViewContact.java:12)
10-16 13:37:20.603: E/AndroidRuntime(869): at java.lang.Class.newInstanceImpl(Native Method)
10-16 13:37:20.603: E/AndroidRuntime(869): at java.lang.Class.newInstance(Class.java:1319)
10-16 13:37:20.603: E/AndroidRuntime(869): at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
10-16 13:37:20.603: E/AndroidRuntime(869): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1870)
10-16 13:37:20.603: E/AndroidRuntime(869): ... 11 more
请告诉我是否需要澄清这个问题。