Android，SQLite rawQuery 在选择 ListView 中的项目后不发送任何结果

Question

我试图在 ListView 中显示选定的项目，在另一个 Activity 中填充了 SQLite，但是当我创建 rawQuery 时，使用 _id 行标识符向它显示另一个 Activity 中的项目，但不发送任何结果，引导我进行其他 Activity ，但没有在 xml 布局中显示任何内容，我不知道我是否正确地做了我的 rawQuery 声明，这是我的搜索代码和我的处理程序来显示它:

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.course_details);

    courseId = getIntent().getIntExtra("COURSE_ID", 0);
    SQLiteDatabase db = (new DBHelper(this)).getWritableDatabase();
    Cursor cursor = db.rawQuery("SELECT emp._id, emp.title, emp.instructor, emp.length, emp.rating, emp.topic, emp.subject, emp.description, mgr._id managerId, mgr.title managerTitle FROM courses emp LEFT OUTER JOIN courses mgr ON emp.title = mgr._id WHERE emp._id = ?", 
            new String[]{""+courseId});


    if (cursor.getCount() == 1)
    {
            cursor.moveToFirst();

            tTitle = (TextView) findViewById(R.id.tTitle);
            tTitle.setText(cursor.getString(cursor.getColumnIndex("title")));

            tInstructor = (TextView) findViewById(R.id.tInstructor);
            tInstructor.setText(cursor.getString(cursor.getColumnIndex("instructor")));

            tLength = (TextView) findViewById(R.id.tLength);
            tLength.setText(cursor.getString(cursor.getColumnIndex("length")));

            tRating = (TextView) findViewById(R.id.tRating);
            tRating.setText(cursor.getString(cursor.getColumnIndex("rating")));

            tTopic = (TextView) findViewById(R.id.tTopic);
            tTopic.setText(cursor.getString(cursor.getColumnIndex("topic")));

            tSubject = (TextView) findViewById(R.id.tSubject);
            tSubject.setText(cursor.getString(cursor.getColumnIndex("subject")));

            tDescription = (TextView) findViewById(R.id.tDescription);
            tDescription.setText(cursor.getString(cursor.getColumnIndex("description")));

    }
    db.close();
    cursor.close();
    return; 
}}

这是显示 ListView 并执行 Intent 的类:

public class lay_main extends ListActivity {
public ListView list;
public DBHelper myAdap;
protected SQLiteDatabase db;
public Cursor cursor;
DBHelper Context;
DBHelper ArrayList;

//adapter cAdapter class
protected ListAdapter adapter;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.lay_main);  

    collectXML();
    setupDataBase();
    setupAdapter();            
}      
private void collectXML() 
{
     list = (ListView)findViewById(android.R.id.list);  

}

public void setupDataBase() {
    myAdap = new DBHelper(getApplicationContext());
    myAdap.insertCourses();     

}

public void setupAdapter()
{
if(myAdap.getCourses()!=null)
    {
    adapter = new  cAdapter(this, R.layout.list_courses, myAdap.getCourses());
    list.setAdapter(adapter);
    }   
}
public void onListItemClick(ListView parent, View view, int position, long id) 
 {
        super.onListItemClick(parent, view, position, id);
        Intent intent = new Intent(this, CourseDetails.class);
        Courses course = (Courses) adapter.getItem(position);
        intent.putExtra("COURSE_ID", course.title);
        startActivity(intent);  
 }}

非常感谢您的帮助。

Answer 1

您可以通过 bundle 发送您的数据:

Bundle sendBundle = new Bundle();
    sendBundle.putString("COURSE_ID", course.title); //or use putInt if course.title is int type
    //sendBundle.putInt("COURSE_ID", course.title);
    Intent i = new Intent(lay_main.this, CourseDetails.class);
    i.putExtra("testBundle", sendBundle);
    startActivity(i);

并像这样接收它:

Bundle receiveBundle = this.getIntent().getBundleExtra("testBundle");
    if (receiveBundle != null){
        String courseId = receiveBundle.getString("COURSE_ID");     
        //or int courseId = receiveBundle.getInt("COURSE_ID");     
        }