我如何显示随机问题。我查看了其他帖子，但那里的答案没有用。这有3个难度容易中等难度。我想每个难度随机提出问题。感谢
QuizActivity：
public class QuizActivity extends Activity {
int score = 0;
int qnum = 1;
TextView txtQuestion;
RadioButton rda, rdb, rdc, rdd;
Button butNext;
RadioGroup rdgrp;
String corAnswer = "";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
setContentView(R.layout.activity_quiz);
DbHelper db = new DbHelper(this);
rdgrp = (RadioGroup) findViewById(R.id.questionAndAnswers);
txtQuestion = (TextView) findViewById(R.id.textView1);
rda = (RadioButton) findViewById(R.id.radio0);
rdb = (RadioButton) findViewById(R.id.radio1);
rdc = (RadioButton) findViewById(R.id.radio2);
rdd = (RadioButton) findViewById(R.id.radio3);
butNext = (Button) findViewById(R.id.button1);
corAnswer = "";
onCreateQuestion();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_quiz, menu);
return true;
}
public void onCreateQuestion() {
String level = getIntent().getExtras().getString("level");
DbHelper db = new DbHelper(this);
db.getQuestByLevel(level, qnum);
txtQuestion.setText(db.question);
rda.setText(db.optionA);
rdb.setText(db.optionB);
rdc.setText(db.optionC);
rdd.setText(db.optionD);
corAnswer = db.answer;
qnum++;
}
public void onClickNext(View view) {
String level = getIntent().getExtras().getString("level");
DbHelper db = new DbHelper(this);
db.getQuestByLevel(level, qnum);
RadioGroup grp = (RadioGroup) findViewById(R.id.questionAndAnswers);
RadioButton answer = (RadioButton) findViewById(grp.getCheckedRadioButtonId());
if (answer == null)
{
Toast.makeText(QuizActivity.this, "select an answer please", Toast.LENGTH_SHORT).show();
return;
}
if (corAnswer!= null && corAnswer.equalsIgnoreCase((String) answer.getText()))
{
score++;
Log.d("answer", "Your score" + score);
}
if (qnum <= 5) {
} else {
Intent intent = new Intent(QuizActivity.this, ResultActivity.class);
Bundle b = new Bundle();
b.putInt("score", score);
intent.putExtras(b);
startActivity(intent);
finish();
}
txtQuestion.setText(db.question);
rda.setText(db.optionA);
rdb.setText(db.optionB);
rdc.setText(db.optionC);
rdd.setText(db.optionD);
corAnswer = db.answer;
qnum++;
rdgrp.clearCheck();
}
}
数据库：
public class DbHelper extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "QUIZ";
private static final String TABLE_QUIZ = "quiz";
private static final String KEY_ID = "id";
private static final String KEY_QUES = "question";
private static final String KEY_ANSWER = "answer";
private static final String KEY_OPTA = "opta";
private static final String KEY_OPTB = "optb";
private static final String KEY_OPTC = "optc";
private static final String KEY_OPTD = "optd";
private static final String q_level = "level";
private static final String QuestionNumber = "q_number";
private SQLiteDatabase dbase;
public String question, optionA, optionB, optionC, optionD, answer;
public DbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
dbase = db;
String sql = "CREATE TABLE IF NOT EXISTS " + TABLE_QUIZ + " ( "
+ KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_QUES
+ " TEXT, " + KEY_ANSWER + " TEXT, " + KEY_OPTA + " TEXT, "
+ KEY_OPTB + " TEXT, " + KEY_OPTC + " TEXT, " + KEY_OPTD +" TEXT, " + q_level + " TEXT, " + QuestionNumber + " INTEGER)";
db.execSQL(sql);
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q1','A1','A2','A3','A4','Answer','EASY','1')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q2','A1','A2','A3','A4','Answer','EASY','2')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q3','A1','A2','A3','A4','Answer','EASY','3')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q4','A1','A2','A3','A4','Answer','EASY','4')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q5','A1','A2','A3','A4','Answer','EASY','5')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q1','A1','A2','A3','A4','Answer','MEDIUM','1')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q1','A1','A2','A3','A4','Answer','MEDIUM','2')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q1','A1','A2','A3','A4','Answer','MEDIUM','3')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q1','A1','A2','A3','A4','Answer','MEDIUM','4')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q1','A1','A2','A3','A4','Answer','MEDIUM','5')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q1','A1','A2','A3','A4','Answer','HARD','1')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q1','A1','A2','A3','A4','Answer','HARD','2')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q1','A1','A2','A3','A4','Answer','HARD','3')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q1','A1','A2','A3','A4','Answer','HARD','4')");
db.execSQL("INSERT INTO " + TABLE_QUIZ + "(" + KEY_QUES + ", " + KEY_OPTA + ", " + KEY_OPTB + ", " + KEY_OPTC + ", " + KEY_OPTD + ", " + KEY_ANSWER + ", " + q_level + ", " + QuestionNumber + ")VALUES(" +
"'Q1','A1','A2','A3','A4','Answer','HARD','5')");
addQuestions();
//db.close();
}
private void addQuestions() {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldV, int newV) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_QUIZ);
onCreate(db);
}
public void getQuestByLevel(String level, int qnum) {
String selectQuery = "SELECT * FROM " + TABLE_QUIZ + " WHERE " + q_level +" = '" + level + "' AND "+QuestionNumber+" = "+qnum+"" ;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
question=cursor.getString(cursor.getColumnIndex(KEY_QUES));
optionA=cursor.getString(cursor.getColumnIndex(KEY_OPTA));
optionB=cursor.getString(cursor.getColumnIndex(KEY_OPTB));
optionC=cursor.getString(cursor.getColumnIndex(KEY_OPTC));
optionD=cursor.getString(cursor.getColumnIndex(KEY_OPTD));
answer=cursor.getString(cursor.getColumnIndex(KEY_ANSWER));
} while (cursor.moveToNext());
}
}
}
logcat的：
01-22 23:23:41.285 8685-8685/com.dreamteam.quiz.project
E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.dreamteam.quiz.project, PID: 8685
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.dreamteam.quiz.project/com.example.quiz.project.QuizActivity}: android.database.sqlite.SQLiteException: near "ORDER": syntax error (code 1): , while compiling: SELECT * FROM quiz WHERE level = 'EASY' AND q_number = 1 + ORDER BY RANDOM() LIMIT 5
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2319)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2370)
at android.app.ActivityThread.access$800(ActivityThread.java:155)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1243)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5426)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.database.sqlite.SQLiteException: near "ORDER": syntax error (code 1): , while compiling: SELECT * FROM quiz WHERE level = 'EASY' AND q_number = 1 + ORDER BY RANDOM() LIMIT 5
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:1112)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:689)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1433)
at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1372)
at com.example.quiz.project.DbHelper.getQuestByLevel(DbHelper.java:97)
at com.example.quiz.project.QuizActivity.onCreateQuestion(QuizActivity.java:60)
at com.example.quiz.project.QuizActivity.onCreate(QuizActivity.java:45)
at android.app.Activity.performCreate(Activity.java:5296)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2283)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2370)
at android.app.ActivityThread.access$800(ActivityThread.java:155)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1243)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5426)
at java.lang.reflect.Method.invokeNative(Native Method)
答案 0 :(得分：0)
使用查询
String selectQuery = "SELECT * FROM " + TABLE_QUIZ + " WHERE " + q_level +" = '" + level + "' AND "+QuestionNumber+" = "+qnum+" + ORDER BY RANDOM() LIMIT 1" ;
我认为通过更改查询，您可以参加解决方案。
答案 1 :(得分：0)
将结果存储在Model类中，然后将其随机化。
class Question{
int id;
String questionText;
String[] options;
}
Question[] questions = new Question[cursor.size()];
//put data into questions
Random rnd = new Random();
for(int i = 0; i < question.length; i++){
//using randomizer swap objects
}
现在选择要显示的TOP 5或10或20个问题，不会有重复，也会是随机顺序