Question

我认为我已经阅读了关于这个主题的所有答案，但没有得到正确答案。

我在一个名为Library的活动中有一个列表视图。当我点击某个项目时，我想在另一个活动中检索有关所点击项目的信息。我希望这些信息可以在不同的领域。您可能会对我的代码了解得更好。

这是图书馆活动，我在其上列出了我称之为“标签”的列表视图：

import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.widget.TextView;


public class InfoTagActivity extends ActionBarActivity {
    TextView textTagName;
    TextView textTagId;
    TextView textTagData;
    String tagId;
    private static final String TAG_NAME = "tag_name";
    private static final String TAG_MID = "tag_mid";
    private static final String TAG_DATA = "tag_data";
    static SQLiteDatabase db = null;
    private DatabaseHelper databaseHelper;
    long tag_id;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_info_tag);
    getSupportActionBar().hide();


    //String tagName = this.getIntent().getStringExtra(TAG_NAME);
    databaseHelper = new DatabaseHelper(this);


    textTagName = (TextView) findViewById(R.id.tagName);
    textTagId = (TextView) findViewById(R.id.tagId);
    textTagData = (TextView) findViewById(R.id.tagInfo);

    Intent intent = getIntent();
    Cursor cursor = databaseHelper.getAllData();

    if (cursor != null && cursor.moveToFirst()) {
        String name = cursor.getString(cursor.getColumnIndex("tag_name"));
        textTagName.append(name);
        String id = cursor.getString(cursor.getColumnIndex("tag_mid"));
        textTagId.append(id);
        String info = cursor.getString(cursor.getColumnIndex("tag_data"));
        textTagData.append(info);
    }

  }
}

DatabaseHelper.java：

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class DatabaseHelper {

private static final String TAG = DatabaseHelper.class.getSimpleName();

// database configuration
// if you want the onUpgrade to run then change the database_version
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "mydatabase.db";

// table configuration
public static final String TABLE_NAME = "person_table";         // Table name
private static final String TAG_ID = "_id";     // a column named "_id" is required for cursor
private static final String TAG_NAME = "tag_name";
private static final String TAG_MID = "tag_mid";
private static final String TAG_DATA = "tag_data";

private DatabaseOpenHelper openHelper;
private SQLiteDatabase database;

// this is a wrapper class. that means, from outside world, anyone will communicate with PersonDatabaseHelper,
// but under the hood actually DatabaseOpenHelper class will perform database CRUD operations
public DatabaseHelper(Context aContext) {

    openHelper = new DatabaseOpenHelper(aContext);
    database = openHelper.getWritableDatabase();
}

public void insertData (String aTagName, String aTagId, String aTagData) {

    // we are using ContentValues to avoid sql format errors

    ContentValues contentValues = new ContentValues();

    contentValues.put(TAG_NAME, aTagName);
    contentValues.put(TAG_MID, aTagId);
    contentValues.put(TAG_DATA, aTagData);

    database.insert(TABLE_NAME, null, contentValues);
}

public Cursor getAllData () {

    String buildSQL = "SELECT * FROM " + TABLE_NAME;

    Log.d(TAG, "getAllData SQL: " + buildSQL);

    return database.rawQuery(buildSQL, null);
}

// this DatabaseOpenHelper class will actually be used to perform database related operation

private class DatabaseOpenHelper extends SQLiteOpenHelper {

    public DatabaseOpenHelper(Context aContext) {
        super(aContext, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        // Create your tables here

        String buildSQL = "CREATE TABLE " + TABLE_NAME + "( " + TAG_ID + " INTEGER PRIMARY KEY, " +
                TAG_NAME + " TEXT, " + TAG_MID + " TEXT, " + TAG_DATA + " TEXT )";

        Log.d(TAG, "onCreate SQL: " + buildSQL);

        sqLiteDatabase.execSQL(buildSQL);
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int oldVersion, int newVersion) {
        // Database schema upgrade code goes here

        String buildSQL = "DROP TABLE IF EXISTS " + TABLE_NAME;

        Log.d(TAG, "onUpgrade SQL: " + buildSQL);

        sqLiteDatabase.execSQL(buildSQL);       // drop previous table

        onCreate(sqLiteDatabase);               // create the table from the beginning
    }
  }
}

InfoTagActivity.java，我想在此活动中获取有关所点击项目的信息：

public class InfoTagActivity extends ActionBarActivity {
TextView textTagName;
TextView textTagId;
TextView textTagData;
String tagId;
private static final String TAG_NAME = "tag_name";
private static final String TAG_MID = "tag_mid";
private static final String TAG_DATA = "tag_data";
static SQLiteDatabase db = null;
private DatabaseHelper databaseHelper;
long tag_id;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_info_tag);
    getSupportActionBar().hide();


    //String tagName = this.getIntent().getStringExtra(TAG_NAME);
    databaseHelper = new DatabaseHelper(this);


    textTagName = (TextView) findViewById(R.id.tagName);
    textTagId = (TextView) findViewById(R.id.tagId);
    textTagData = (TextView) findViewById(R.id.tagInfo);

    Intent intent = getIntent();
    Cursor cursor = databaseHelper.getAllData();

    if (cursor != null && cursor.moveToFirst()) {
        String name = cursor.getString(cursor.getColumnIndex("tag_name"));
        textTagName.append(name);
        String id = cursor.getString(cursor.getColumnIndex("tag_mid"));
        textTagId.append(id);
        String info = cursor.getString(cursor.getColumnIndex("tag_data"));
        textTagData.append(info);
    }

  }
}

使用关联的activity_info_tag.xml：

<RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_below="@+id/relativeLayout"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:layout_above="@+id/relativeLayout2"
    android:paddingTop="10dp">

    <TextView
        android:id="@+id/tagId"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"

        android:textColor="@color/main_theme_blue"
        android:paddingLeft="5dp"
        android:paddingRight="5dp"
        android:layout_above="@+id/tagDate"
        android:layout_toRightOf="@+id/tagIdText"
        android:layout_toEndOf="@+id/tagIdText" />

    <TextView
        android:id="@+id/tagDate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"

        android:textColor="@color/main_theme_blue"
        android:layout_alignTop="@+id/tagDateText"
        android:layout_toRightOf="@+id/tagDateText"
        android:layout_toEndOf="@+id/tagDateText"
        android:paddingLeft="5dp"
        android:paddingRight="5dp"/>

    <TextView
        android:id="@+id/tagInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"

        android:textColor="@color/main_theme_blue"
        android:layout_below="@+id/tagDate"
        android:layout_toRightOf="@+id/tagInfoText"
        android:layout_toEndOf="@+id/tagInfoText"
        android:paddingLeft="5dp"
        android:paddingRight="5dp"
        />

</RelativeLayout>

我的问题是，到目前为止，当我点击列表视图的标签时，它总是只向我提供有关第一个标签的信息。我想获得有关我点击的标签的信息。有人可以帮我吗？

非常感谢您的回答！

检索数据库Android中的特定行数据

0 个答案: