Question

在主Activity中我定义了按钮并将它们放在onclicklistener上。当我想从数据库填充列表视图时，问题出现在viewAll按钮中我调用方法db.getAllContacts（）但代码不起作用

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

        name = (EditText)findViewById(R.id.editText1);
        phone = (EditText)findViewById(R.id.editText2);
        btnViewAll=(Button)findViewById(R.id.button1);
        btnAdd=(Button)findViewById(R.id.button2);
        btnAdd.setOnClickListener(this);
        btnViewAll.setOnClickListener(this);

    }

@Override
    public void onClick(View view) {
    MySQLiteHelper db = new MySQLiteHelper(this);
if(view==btnViewAll) {
        if(name.getText().toString().trim().length()==0 || phone.getText().toString().trim().length()==0)
        {
            showMessage("Error", "Please enter all values");
            return;
        }
      else{
          List<Contact> contact = new ArrayList<Contact>(); 
          contact= db.getAllContacts();     
          ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, contact); 
          ListView listContent = (ListView)findViewById(R.id.List);
          listContent.setAdapter(adapter);
        }
    }
}

    public void showMessage(String title,String message)
    {
        Builder builder=new Builder(this);
        builder.setCancelable(true);
        builder.setTitle(title);
        builder.setMessage(message);
        builder.show();
    }
    public void clearText()
    {
        name.setText("");
        phone.setText("");
    }

在SQLiteHelper文件中：

   public List<Contact> getAllContacts() {
        List<Contact> contactList = new ArrayList<Contact>();
        // Select All Query
        String selectQuery = "SELECT  * FROM contact";
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);
        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
            Contact contact = new Contact();
            contact.setId(Integer.parseInt(cursor.getString(0)));
            contact.setName(cursor.getString(1));
            contact.setPhone(cursor.getString(2));
            // Adding contact to list
            contactList.add(contact);
        } while (cursor.moveToNext());
    }// return contact list
    return contactList;}

请帮帮我

Answer 1

删除此行： -

ArrayAdapter adapter = new ArrayAdapter（this，android.R.layout.simple_list_item_1，contact）;

并添加： -

ContactListAdapter contactListAdapter = new ContactListAdapter（this，R.layout.contact_list_item，contact）;

ContactListAdapter类： -

public class ContactListAdapter extends ArrayAdapter<Contact> {
// Declare Variables
Context context;
LayoutInflater inflater;
List<Contact> contactlist;

public ContactListAdapter(Context context, int resourceId,
        List<Contact> contactlist) {
    super(context, resourceId, contactlist);

    this.context = context;
    this.contactlist = contactlist;
    inflater = LayoutInflater.from(context);
}

private class ViewHolder {
    TextView contactId;
    TextView contactName;
    TextView contactPhone;


}

public View getView(int position, View view, ViewGroup parent) {
    final ViewHolder holder;
    if (view == null) {
        holder = new ViewHolder();
        view = inflater.inflate(R.layout.contact_list_item, null);
        // Locate the TextViews in listview_item.xml
         holder.contactName = (TextView) view.findViewById(R.id.contact_id);
        holder.contactName = (TextView) view.findViewById(R.id.contact_name);
        holder.contactPhone = (TextView) view.findViewById(R.id.contact_phone);

        view.setTag(holder);
    } else {
        holder = (ViewHolder) view.getTag();
    }
    // Capture position and set to the TextViews
     holder.contactId.setText(contactlist.get(position).getContactId());
    holder.contactName.setText(contactlist.get(position).getContactName());
    holder.contactPhone.setText(contactlist.get(position).getContactPhone());


    return view;
}

}

和contact_list_item.xml： -

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="10dp">

<TextView
    android:id="@+id/contact_id"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textColor="#000000"
    android:text="test"/>

<TextView
    android:id="@+id/contact_name"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textColor="#000000"
    android:text="test"/>

<TextView
    android:id="@+id/contact_phone"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="TextView" />

Answer 2

数据库访问对象逻辑很好。主要问题在于数组适配器。您应该尝试在Activity中实现ListAdapter，而不是使用ArrayAdapter

从数据库填充ListView

2 个答案: