我的问题是，当我打开ViewContact类时，所有字段都是空白的，除了名称，它显示了注释条目。我没有在SQLite或一般数据库方面的经验。我会发布所有相关代码。我认为这可能与光标有关，但同样，我对此还不太了解。谢谢你的帮助。
ContactsMenu class
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, DatabaseSetup.colMail, DatabaseSetup.colPhone1,
DatabaseSetup.colPhone2, DatabaseSetup.colAddress, DatabaseSetup.colNotes };
Cursor cursor;
public static String name, email, phone1, phone2, address, 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);
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,
R.id.item_text2, R.id.item_text3, R.id.item_text4,
R.id.item_text5, R.id.item_text6})
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;
}
}
ViewContacts类
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;
import android.widget.TextView;
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.textName);
mailield = (EditText) findViewById(R.id.textMail);
phoneField1 = (EditText) findViewById(R.id.textPhone1);
phoneField2 = (EditText) findViewById(R.id.textPhone2);
addressField = (EditText) findViewById(R.id.textAddress);
notesField = (EditText) findViewById(R.id.textNotes);
name =ContactsMenu.getName();
mail =ContactsMenu.getEmail();
phone1 =ContactsMenu.getPhone1();
phone2 =ContactsMenu.getPhone2();
address =ContactsMenu.getAddress();
notes =ContactsMenu.getNotes();
nameField.setText(name, TextView.BufferType.EDITABLE);
mailield.setText(mail, TextView.BufferType.EDITABLE);
phoneField1.setText(phone1, TextView.BufferType.EDITABLE);
phoneField2.setText(phone2, TextView.BufferType.EDITABLE);
addressField.setText(address, TextView.BufferType.EDITABLE);
notesField.setText(notes, TextView.BufferType.EDITABLE);
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(){
}
}
DatabaseSetup类
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";
}
Logcat条目
10-22 14:49:51.418: E/AndroidRuntime(959): FATAL EXCEPTION: main
10-22 14:49:51.418: E/AndroidRuntime(959): java.lang.RuntimeException: Unable to resume activity {com.emailandcontactmanager/com.emailandcontactmanager.ContactsMenu}: java.lang.IllegalStateException: trying to requery an already closed cursor android.database.sqlite.SQLiteCursor@4138a990
10-22 14:49:51.418: E/AndroidRuntime(959): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2443)
10-22 14:49:51.418: E/AndroidRuntime(959): at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2471)
10-22 14:49:51.418: E/AndroidRuntime(959): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1172)
10-22 14:49:51.418: E/AndroidRuntime(959): at android.os.Handler.dispatchMessage(Handler.java:99)
10-22 14:49:51.418: E/AndroidRuntime(959): at android.os.Looper.loop(Looper.java:137)
10-22 14:49:51.418: E/AndroidRuntime(959): at android.app.ActivityThread.main(ActivityThread.java:4340)
10-22 14:49:51.418: E/AndroidRuntime(959): at java.lang.reflect.Method.invokeNative(Native Method)
10-22 14:49:51.418: E/AndroidRuntime(959): at java.lang.reflect.Method.invoke(Method.java:511)
10-22 14:49:51.418: E/AndroidRuntime(959): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
10-22 14:49:51.418: E/AndroidRuntime(959): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
10-22 14:49:51.418: E/AndroidRuntime(959): at dalvik.system.NativeStart.main(Native Method)
10-22 14:49:51.418: E/AndroidRuntime(959): Caused by: java.lang.IllegalStateException: trying to requery an already closed cursor android.database.sqlite.SQLiteCursor@4138a990
10-22 14:49:51.418: E/AndroidRuntime(959): at android.app.Activity.performRestart(Activity.java:4508)
10-22 14:49:51.418: E/AndroidRuntime(959): at android.app.Activity.performResume(Activity.java:4531)
10-22 14:49:51.418: E/AndroidRuntime(959): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2433)
10-22 14:49:51.418: E/AndroidRuntime(959): ... 10 more
答案 0 :(得分：1)
您的问题是您没有正确使用SimpleCursorAdapter (Context context, int layout, Cursor c, String[] from, int[] to)。您有from数组，其中包含要从表中显示的列，to数组应包含显示列的视图。
to中的字段数应该等于from，否则您将拥有的行为只有from中的第一列映射到R.id.item_text }。
<强>更新
由于您只想显示要显示的名称列，因此请勿使用ListView填充游标cursor = (Cursor) listView.getItemAtPosition(position);。你应该替换：
Cursor cursor = (Cursor) listView.getItemAtPosition(position);
使用：
Cursor cursor = DatabaseSetup.getContactData();
StartManagingCursor(cursor);
cursor.moveToFirst();
由于您稍后使用此cursor来填充传递给其他活动的值，因此您无法从listView.getItemAtPosition(position);获取该值，因为位置position只有一个项目（是名称列），因此其他项目提供NullPointerException，因为从cursor
listView.getItemAtPosition(position);中不存在这些项目
更新2：
此外：
setName(selectedName);
setName(selectedEmail);
setName(selectedPhone1);
setName(selectedPhone2);
setName(selectedAddress);
setName(selectedNotes);
应该是：
setName(selectedName);
setEmail(selectedEmail);
setPhone1(selectedPhone1);
setPhone2(selectedPhone2);
setAddress(selectedAddress);
setNotes(selectedNotes);