java - 如何在 TextView 中显示数据库查询？

Question

我必须为一个大学项目制作一个 Hangman 应用程序，目前我已经创建了一个 SQLite 数据库并在其中添加了一些单词。我正在尝试运行查询来选择随机单词并将其显示在 TextView 中，但在显示结果时遇到问题。

这就是我目前所拥有的

import android.os.Bundle;
import android.app.Activity;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.util.Log;
import android.view.Menu;
import android.widget.Button;
import android.widget.TextView;

class Hangman extends Activity {

public TextView wordText;
public Button button02A;
private Button button01B;
private Button button03C;
private Button button04D;
private Button button05E;
private Button button06F;
private Button button07G;
private Button button1H;
private Button button09I;
private Button button10J;
private Button button11K;
private Button button12L;
private Button button13M;
private Button button14N;
private Button button15O;
private Button button16P;
private Button button18Q;
private Button button19R;
private Button button20S;
private Button button21T;
private Button button17U;
private Button button22V;
private Button button23W;
private Button button08X;
private Button button25Y;
private Button button26Z;
private Button button24Voice;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_hangman);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_hangman, menu);
    return true;
}

public void assignButtons() {

    wordText = (TextView) findViewById(R.id.wordText);
    button02A = (Button) findViewById(R.id.Button02);
    button01B = (Button) findViewById(R.id.Button01);
    button03C = (Button) findViewById(R.id.Button03);
    button04D = (Button) findViewById(R.id.Button04);
    button05E = (Button) findViewById(R.id.Button05);
    button06F = (Button) findViewById(R.id.Button06);
    button07G = (Button) findViewById(R.id.Button07);
    button1H = (Button) findViewById(R.id.button1);
    button09I = (Button) findViewById(R.id.Button09);
    button10J = (Button) findViewById(R.id.Button10);
    button11K = (Button) findViewById(R.id.Button11);
    button12L = (Button) findViewById(R.id.Button12);
    button13M = (Button) findViewById(R.id.Button13);
    button14N = (Button) findViewById(R.id.Button14);
    button15O = (Button) findViewById(R.id.Button15);
    button16P = (Button) findViewById(R.id.Button16);
    button18Q = (Button) findViewById(R.id.Button18);
    button19R = (Button) findViewById(R.id.Button19);
    button20S = (Button) findViewById(R.id.Button20);
    button21T = (Button) findViewById(R.id.Button21);
    button17U = (Button) findViewById(R.id.Button17);
    button22V = (Button) findViewById(R.id.Button22);
    button23W = (Button) findViewById(R.id.Button23);
    button08X = (Button) findViewById(R.id.Button08);
    button25Y = (Button) findViewById(R.id.Button25);
    button26Z = (Button) findViewById(R.id.Button26);
    button24Voice = (Button) findViewById(R.id.Button24);
}

}

class NewDatabase extends SQLiteOpenHelper {

//Create Database   
private static final String DATABASE_NAME = "myDatabase.db";
private static final String DATABASE_TABLE ="Puzzles";
public static final String COLUMN_PUZZLES = "Puzzlescol";
public static final String COLUMN_ID = "_id";
private static final int DATABASE_VERSION = 1;

private static final String DATABASE_CREATE = "create table "
          + DATABASE_TABLE + "(" + COLUMN_ID
          + " integer primary key autoincrement, " + COLUMN_PUZZLES
          + " text not null);";


public NewDatabase(Context context, String name,
CursorFactory factory, int version) {
super(context, name, factory, version);
}
//Overriding onCreate and onUpgrade to create database
  @Override
  public void onCreate(SQLiteDatabase database) {
    database.execSQL(DATABASE_CREATE);
  }

  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    Log.w(NewDatabase.class.getName(),
        "Upgrading database from version " + oldVersion + " to "
            + newVersion + ", which will destroy all old data");
    db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
    onCreate(db);
    }

public void insertRows(){
    ContentValues values = new ContentValues();

    values.put(COLUMN_ID, "1");
    values.put(COLUMN_PUZZLES, "MERMAID");
    values.put(COLUMN_ID, "2");
    values.put(COLUMN_PUZZLES, "SUITCASE");
    values.put(COLUMN_ID, "3");
    values.put(COLUMN_PUZZLES, "OSTRICH");

  }

public String randWord() {
    SQLiteDatabase db  = this.getReadableDatabase();
    Cursor cur = db.query("DATABASE_TABLE Order BY RANDOM() LIMIT 1",
    new String[] { "*" }, null, null, null, null, null);

        return cur.getString(cur.getColumnIndex(COLUMN_PUZZLES));
}

public void showWord(Cursor cur) {
    wordText.setText(cur);

}
}

Answer 1

创建自己的 Hungman 应用程序。创建基础 DBHelper。添加一些单词来测试。设置刽子手逻辑。

最好动态创建 UI 元素。将布局创建为新元素的框，但以编程方式将其放在那里。

private LinearLayout lettersLayout;
private final String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; ***
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_hangman);
lettersLayout = (LinearLayout) findViewById(R.id.lettersLay); **
for (String alphabetLetter : alphabet.split("(?!^)")) {
TextView alphabetLetterTxt = new TextView(this);
alphabetLetterTxt.setText(alphabetLetter);
lettersLayout.addView(alphabetLetter);
}

以下是使用 SQLitte 数据库的简单示例:

public class DBHelper extends SQLiteOpenHelper {

private static DBHelper instance;
private static final String DATABASE_NAME = "HangmanBase";
    private static final int DATABASE_VERSION = 5;
public static interface WORD extends BaseColumns {
        String TABLE_NAME = "wordTable";
        String WORD = "word";
        String DESCRIPTION = "wordDescription";
    }
private static final String CREATE_TABLE = "CREATE TABLE IF NOT EXISTS ";
    private static final String DROP_TABLE = "DROP TABLE IF EXISTS ";
    private static final String UNIQUE = "UNIQUE ON CONFLICT ABORT";
private static final String CREATE_TABLE_WORD = CREATE_TABLE + WORD.TABLE_NAME + " (" + WORD._ID
            + " INTEGER PRIMARY KEY, " + WORD.WORD + " TEXT " + UNIQUE + ", " + WORD.DESCRIPTION + " TEXT);";
private DBHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }
public static DBHelper getInstance(Context context) {
        if (instance == null) {
            instance = new DBHelper(context);
        }
        return instance;
    }
@Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_TABLE_WORD);
    }
@Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL(DROP_TABLE + WORD.TABLE_NAME);
        onCreate(db);
    }
public long addWord(String newWord, String newWordDescription) {
        ContentValues values = new ContentValues();
        values.put(WORD.WORD.toUpperCase(Locale.UK), newWord);
        values.put(WORD.DESCRIPTION, newWordDescription);
        return getWritableDatabase().insert(WORD.TABLE_NAME, null, values);
    }
public HangmanWord getRandomWord() {
        Cursor allWordsList = getReadableDatabase().rawQuery("SELECT * FROM " + WORD.TABLE_NAME, null);
        if (allWordsList != null && allWordsList.getCount() > 0) {
            Random random = new Random();
            allWordsList.moveToPosition(random.nextInt(allWordsList.getCount()));
            return new HangmanWord(allWordsList.getString(allWordsList.getColumnIndex(WORD.WORD)),
                    allWordsList.getString(allWordsList.getColumnIndex(WORD.DESCRIPTION)));
        }
        return null;
    }
}