我正在构建一个应用程序，每当我点击＆＃34; next＆＃34;时，就会从SQLite数据库中用一个随机记录填充ListView。猜谜式游戏的按钮。目前我可以在应用程序打开时从数据库中提取随机记录，但是，我不知道我是否需要新的课程，而且我不知道在哪里放置代码＆＃34; next＆＃34;按钮，我也不知道代码应该是什么。我每次有人点击按下＆＃34; next＆＃34;的按钮时，我基本上都试图让应用程序用DB中的新单个随机记录刷新ListView。我已经完成了xml布局，应用程序打开并完美显示第一个随机记录。感谢您的任何帮助！ ：）
MainActivity类：
package com.example.derek.guessinggame;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.view.Menu;
import android.view.MenuInflater;
public class MainActivity extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FragmentManager fragmentManager = getSupportFragmentManager();
if (fragmentManager.findFragmentById(android.R.id.content) == null) {
GuessListFragment guessListFragment = new GuessListFragment();
fragmentManager.beginTransaction().add(android.R.id.content, guessListFragment).commit();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_main, menu);
return super.onCreateOptionsMenu(menu);
}
ContentProvider类：
package com.example.derek.guessinggame;
import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.provider.BaseColumns;
import android.text.TextUtils;
import android.util.Log;
public class GuessProvider extends ContentProvider {
private GuessDatabase mOpenHelper;
private static final String TAG = GuessProvider.class.getSimpleName();
private static final UriMatcher sUriMatcher = buildUriMatcher();
private static final int GUESS = 100;
private static final int GUESS_ID = 101;
private Uri uri;
private String selection;
private String[] selectionArgs;
private static UriMatcher buildUriMatcher() {
final UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);
final String authority = GuessContract.CONTENT_AUTHORITY;
matcher.addURI(authority, "guess", GUESS);
matcher.addURI(authority, "guess/*", GUESS_ID);
return matcher;
}
@Override
public boolean onCreate() {
mOpenHelper = new GuessDatabase(getContext());
return true;
}
private void deleteDatabase() {
mOpenHelper.close();
GuessDatabase.deleteDatabase(getContext());
mOpenHelper = new GuessDatabase(getContext());
}
@Override
public String getType(Uri uri) {
final int match = sUriMatcher.match(uri);
switch (match) {
case GUESS:
return GuessContract.Guess.CONTENT_TYPE;
case GUESS_ID:
return GuessContract.Guess.CONTENT_ITEM_TYPE;
default:
throw new IllegalArgumentException("Unknown Uri: " + uri);
}
}
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
final SQLiteDatabase db = mOpenHelper.getReadableDatabase();
final int match = sUriMatcher.match(uri);
SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();
queryBuilder.setTables(GuessDatabase.Tables.GUESS);
switch (match) {
case GUESS:
// do nothing
break;
case GUESS_ID:
String id = GuessContract.Guess.getGuessId(uri);
queryBuilder.appendWhere(BaseColumns._ID + "=" + id);
break;
default:
throw new IllegalArgumentException("Unknown Uri: " + uri);
}
Cursor cursor = queryBuilder.query(db, projection, selection, selectionArgs, null, null, sortOrder);
return cursor;
}
@Override
public Uri insert(Uri uri, ContentValues values) {
Log.v(TAG, "insert(uri=" + uri + ", values=" + values.toString());
final SQLiteDatabase db = mOpenHelper.getWritableDatabase();
final int match = sUriMatcher.match(uri);
switch (match) {
case GUESS:
long recordId = db.insertOrThrow(GuessDatabase.Tables.GUESS, null, values);
return GuessContract.Guess.buildGuessUri(String.valueOf(recordId));
default:
throw new IllegalArgumentException("Unknown Uri: " + uri);
}
}
@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
Log.v(TAG, "update(uri=" + uri + ", values=" + values.toString());
final SQLiteDatabase db = mOpenHelper.getWritableDatabase();
final int match = sUriMatcher.match(uri);
String selectionCriteria = selection;
switch (match) {
case GUESS:
// do nothing
break;
case GUESS_ID:
String id = GuessContract.Guess.getGuessId(uri);
selectionCriteria = BaseColumns._ID + "=" + id
+ (!TextUtils.isEmpty(selection) ? " AND (" + selection + ")" : "");
break;
default:
throw new IllegalArgumentException("Unknown Uri: " + uri);
}
return db.update(GuessDatabase.Tables.GUESS, values, selectionCriteria, selectionArgs);
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
Log.v(TAG, "delete(uri=" + uri);
if (uri.equals(GuessContract.BASE_CONTENT_URI)) {
deleteDatabase();
return 0;
}
final SQLiteDatabase db = mOpenHelper.getWritableDatabase();
final int match = sUriMatcher.match(uri);
switch (match) {
case GUESS_ID:
String id = GuessContract.Guess.getGuessId(uri);
String selectionCriteria = BaseColumns._ID + "=" + id
+ (!TextUtils.isEmpty(selection) ? " AND (" + selection + ")" : "");
return db.delete(GuessDatabase.Tables.GUESS, selectionCriteria, selectionArgs);
default:
throw new IllegalArgumentException("Unknown Uri: " + uri);
}
}
}
ListLoader类：
package com.example.derek.guessinggame;
import android.content.ContentResolver;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.provider.BaseColumns;
import android.support.v4.content.AsyncTaskLoader;
import android.util.Log;
import java.util.ArrayList;
import java.util.List;
public class GuessListLoader extends AsyncTaskLoader<List<Guess>> {
private static final String LOG_TAG = GuessListLoader.class.getSimpleName();
private List<Guess> mGuess;
private ContentResolver mContentResolver;
private Cursor mCursor;
public GuessListLoader(Context context, Uri uri, ContentResolver contentResolver) {
super(context);
mContentResolver = contentResolver;
}
@Override
public List<Guess> loadInBackground() {
String[] projection = {BaseColumns._ID,
GuessContract.GuessColumns.GUESS_TITLE,
GuessContract.GuessColumns.GUESS_ANSWER,
GuessContract.GuessColumns.GUESS_HINT1,
GuessContract.GuessColumns.GUESS_HINT2,
GuessContract.GuessColumns.GUESS_HINT3,
GuessContract.GuessColumns.GUESS_HINT4,
GuessContract.GuessColumns.GUESS_HINT5};
List<Guess> entries = new ArrayList<Guess>();
mCursor = mContentResolver.query(GuessContract.URI_TABLE, projection, null, null, " random()");
if (mCursor != null) {
if (mCursor.moveToFirst()) {
do {
int _id = mCursor.getInt(mCursor.getColumnIndex(BaseColumns._ID));
String title = mCursor.getString(mCursor.getColumnIndex(GuessContract.GuessColumns.GUESS_TITLE));
String answer = mCursor.getString(mCursor.getColumnIndex(GuessContract.GuessColumns.GUESS_ANSWER));
String hint1 = mCursor.getString(mCursor.getColumnIndex(GuessContract.GuessColumns.GUESS_HINT1));
String hint2 = mCursor.getString(mCursor.getColumnIndex(GuessContract.GuessColumns.GUESS_HINT2));
String hint3 = mCursor.getString(mCursor.getColumnIndex(GuessContract.GuessColumns.GUESS_HINT3));
String hint4 = mCursor.getString(mCursor.getColumnIndex(GuessContract.GuessColumns.GUESS_HINT4));
String hint5 = mCursor.getString(mCursor.getColumnIndex(GuessContract.GuessColumns.GUESS_HINT5));
Guess guess = new Guess(_id, title, answer, hint1, hint2, hint3, hint4, hint5);
entries.add(guess);
} while (mCursor.isLast());
}
}
return entries;
}
@Override
public void deliverResult(List<Guess> guess) {
if (isReset()) {
if (guess != null) {
mCursor.close();
}
}
List<Guess> oldGuessList = mGuess;
if (mGuess == null || mGuess.size() == 0) {
Log.d(LOG_TAG, "++++++++ No data returned");
}
mGuess = guess;
if (isStarted()) {
super.deliverResult(guess);
}
if (oldGuessList != null && oldGuessList != guess) {
mCursor.close();
}
}
@Override
protected void onStartLoading() {
if (mGuess != null) {
deliverResult(mGuess);
}
if (takeContentChanged() || mGuess == null) {
forceLoad();
}
}
@Override
protected void onStopLoading() {
cancelLoad();
}
@Override
protected void onReset() {
onStopLoading();
if (mCursor != null) {
mCursor.close();
}
mGuess = null;
}
@Override
public void onCanceled(List<Guess> guess) {
super.onCanceled(guess);
if (mCursor != null) {
mCursor.close();
}
}
@Override
public void forceLoad() {
super.forceLoad();
}
}
ListFragment类：
package com.example.derek.guessinggame;
import android.content.ContentResolver;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.Loader;
import java.util.List;
public class GuessListFragment extends ListFragment
implements LoaderManager.LoaderCallbacks<List<Guess>> {
private static final String LOG_TAG = GuessListFragment.class.getSimpleName();
private GuessCustomAdapter mAdapter;
private static final int LOADER_ID = 1;
private ContentResolver mContentResolver;
private List<Guess> mGuess;
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
setHasOptionsMenu(true);
mContentResolver = getActivity().getContentResolver();
mAdapter = new GuessCustomAdapter(getActivity(), getChildFragmentManager());
setEmptyText("No entries");
setListAdapter(mAdapter);
setListShown(false);
getLoaderManager().initLoader(LOADER_ID, null, this);
}
@Override
public Loader<List<Guess>> onCreateLoader(int id, Bundle args) {
mContentResolver = getActivity().getContentResolver();
return new GuessListLoader(getActivity(), GuessContract.URI_TABLE, mContentResolver);
}
@Override
public void onLoadFinished(Loader<List<Guess>> loader, List<Guess> guess) {
mAdapter.setData(guess);
mGuess = guess;
if(isResumed()) {
setListShown(true);
} else {
setListShownNoAnimation(true);
}
}
@Override
public void onLoaderReset(Loader<List<Guess>> loader) {
mAdapter.setData(null);
}
}
SQLiteOpenHelper类：
package com.example.derek.guessinggame;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.provider.BaseColumns;
public class GuessDatabase extends SQLiteOpenHelper {
private static final String TAG = GuessDatabase.class.getSimpleName();
private static final String DATABASE_NAME = "guess.db";
private static final int DATABASE_VERSION = 2;
private final Context mContext;
interface Tables {
String GUESS = "guess";
}
public GuessDatabase(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
mContext = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE " + Tables.GUESS + " ("
+ BaseColumns._ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
+ GuessContract.GuessColumns.GUESS_TITLE + " TEXT NOT NULL,"
+ GuessContract.GuessColumns.GUESS_ANSWER + " TEXT NOT NULL,"
+ GuessContract.GuessColumns.GUESS_HINT1 + " TEXT NOT NULL,"
+ GuessContract.GuessColumns.GUESS_HINT2 + " TEXT NOT NULL,"
+ GuessContract.GuessColumns.GUESS_HINT3 + " TEXT NOT NULL,"
+ GuessContract.GuessColumns.GUESS_HINT4 + " TEXT NOT NULL,"
+ GuessContract.GuessColumns.GUESS_HINT5 + " TEXT NOT NULL)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
int version = oldVersion;
if (version == 1) {
version = 2;
}
if (version != DATABASE_VERSION) {
db.execSQL("DROP TABLE IF EXISTS " + Tables.GUESS);
onCreate(db);
}
}
public static void deleteDatabase(Context context) {
context.deleteDatabase(DATABASE_NAME);
}
}
ArrayAdapter类：
package com.example.derek.guessinggame;
import android.content.Context;
import android.support.v4.app.FragmentManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import java.util.List;
public class GuessCustomAdapter extends ArrayAdapter<Guess> {
private LayoutInflater mLayoutInflater;
private static FragmentManager sFragmentManager;
public GuessCustomAdapter(Context context, FragmentManager fragmentManager) {
super(context, android.R.layout.simple_expandable_list_item_2);
mLayoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
sFragmentManager = fragmentManager;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
final View view;
if (convertView == null) {
view = mLayoutInflater.inflate(R.layout.custom_guess, parent, false);
} else {
view = convertView;
}
final Guess guess = getItem(position);
final int _id = guess.getId();
final String title = guess.getTitle();
final String answer = guess.getAnswer();
final String hint1 = guess.getHint1();
final String hint2 = guess.getHint2();
final String hint3 = guess.getHint3();
final String hint4 = guess.getHint4();
final String hint5 = guess.getHint5();
((TextView) view.findViewById(R.id.guess_title)).setText(title);
((TextView) view.findViewById(R.id.guess_answer)).setText(answer);
((TextView) view.findViewById(R.id.guess_hint1)).setText(hint1);
((TextView) view.findViewById(R.id.guess_hint2)).setText(hint2);
((TextView) view.findViewById(R.id.guess_hint3)).setText(hint3);
((TextView) view.findViewById(R.id.guess_hint4)).setText(hint4);
((TextView) view.findViewById(R.id.guess_hint5)).setText(hint5);
return view;
}
public void setData(List<Guess> guesses) {
clear();
if (guesses != null) {
for (Guess guess : guesses) {
add(guess);
}
}
}
}
合同类：
package com.example.derek.guessinggame;
import android.net.Uri;
import android.provider.BaseColumns;
public class GuessContract {
interface GuessColumns{
String GUESS_ID = "_id";
String GUESS_TITLE = "guess_title";
String GUESS_ANSWER = "guess_answer";
String GUESS_HINT1 = "guess_hint1";
String GUESS_HINT2 = "guess_hint2";
String GUESS_HINT3 = "guess_hint3";
String GUESS_HINT4 = "guess_hint4";
String GUESS_HINT5 = "guess_hint5";
}
public static final String CONTENT_AUTHORITY = "com.example.derek.guessinggame.provider";
public static final Uri BASE_CONTENT_URI = Uri.parse("content://" + CONTENT_AUTHORITY);
private static final String PATH_GUESS = "guess";
public static final Uri URI_TABLE = Uri.parse(BASE_CONTENT_URI.toString() + "/" + PATH_GUESS);
public static final String[] TOP_LEVEL_PATHS = {
PATH_GUESS
};
public static class Guess implements GuessColumns, BaseColumns {
public static final Uri CONTENT_URI =
BASE_CONTENT_URI.buildUpon().appendEncodedPath(PATH_GUESS).build();
public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd." + CONTENT_AUTHORITY + ".guess";
public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/vnd." + CONTENT_AUTHORITY + ".guess";
public static Uri buildGuessUri(String guessId) {
return CONTENT_URI.buildUpon().appendEncodedPath(guessId).build();
}
public static String getGuessId(Uri uri) {
return uri.getPathSegments().get(1);
}
}
}
Getters and Setter类：
package com.example.derek.guessinggame;
public class Guess {
private int _id;
private String title;
private String answer;
private String hint1;
private String hint2;
private String hint3;
private String hint4;
private String hint5;
public Guess(int _id, String title, String answer, String hint1, String hint2, String hint3, String hint4, String hint5) {
this._id = _id;
this.title = title;
this.answer = answer;
this.hint1 = hint1;
this.hint2 = hint2;
this.hint3 = hint3;
this.hint4 = hint4;
this.hint5 = hint5;
}
public int getId() {
return _id;
}
public void setId(int _id) {
this._id = _id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getAnswer() {
return answer;
}
public void setAnswer(String answer) {
this.answer = answer;
}
public String getHint1() {
return hint1;
}
public void setHint1(String hint1) {
this.hint1 = hint1;
}
public String getHint2() {
return hint2;
}
public void setHint2(String hint2) {
this.hint2 = hint2;
}
public String getHint3() {
return hint3;
}
public void setHint3(String hint3) {
this.hint3 = hint3;
}
public String getHint4() {
return hint4;
}
public void setHint4(String hint4) {
this.hint4 = hint4;
}
public String getHint5() {
return hint5;
}
public void setHint5(String hint5) {
this.hint5 = hint5;
}
}