Android - ToDoList(定製ArrayAdapter)

ToDoList(定製ArrayAdapter)

本文地址: http://blog.csdn.net/caroline_wendy/article/details/21401907

前置項目參見: http://blog.csdn.net/caroline_wendy/article/details/21330733

環境: Android Studio 0.5.1

ArrayAdapter使用泛型(模板)把Adapter視圖綁定到一個指定類的對象的數組;

定製ArrayAdapter需要重寫getView()方法, 向布局視圖指派至屬性;

ToDoList在每一項後面添加時間, 需要建立ToDoItem對象, 使用定製的ArrayAdapter;

步驟:

1. 建立ToDoItem對象

位置: java->package->ToDoItem

package mzx.spike.todolist.app;import java.text.SimpleDateFormat;import java.util.Date;/** * Created by Administrator on 14-3-17. */public class ToDoItem {    String task;    Date created;    public String getTask() {        return task;    }    public Date getCreated() {        return created;    }    public ToDoItem(String _task) {        this(_task, new Date(java.lang.System.currentTimeMillis()));    }    public ToDoItem(String _task, Date _created) {        task = _task;        created = _created;    }    @Override    public String toString() {        SimpleDateFormat sdf = new SimpleDateFormat("dd/mm/yy");        String dateString = sdf.format(created);        return "(" + dateString + ") " + task;    }}

詳解:

兩個私人變數, 儲存任務(task)和日期(date), 兩種構造方法, 重寫了toString方法;

2. 修改todolist_item布局(xml)

位置: res->layout->todolist_item.xml

詳解:

1. 使用RelativeLayout(相關)布局;

2. TextView儲存日期(date);

3. ToDoListItemView(定製, java)儲存任務(task);

4. layout_toLeftOf屬性, 表示位於某個視圖的左邊;

5. fadingEdge標籤, 褪去邊緣, 遺棄, 被requiresFadingEdge標籤代替;

3. 建立ToDoItemAdapter, 定製適配器

位置: java->package->ToDoItemAdapter

package mzx.spike.todolist.app;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ArrayAdapter;import android.widget.LinearLayout;import android.widget.TextView;import java.text.SimpleDateFormat;import java.util.Date;import java.util.List;/** * Created by Administrator on 14-3-17. */public class ToDoItemAdapter extends ArrayAdapter {    int resource;    public ToDoItemAdapter(Context context, int _resource, List items) {        super(context, _resource, items);        this.resource = _resource;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        LinearLayout toDoView;        ToDoItem item = getItem(position);        String taskString = item.getTask();        Date createdDate = item.getCreated();        SimpleDateFormat sdf = new SimpleDateFormat("dd/mm/yy");        String dateString = sdf.format(createdDate);        if (convertView == null) {            toDoView = new LinearLayout(getContext());            String inflater = Context.LAYOUT_INFLATER_SERVICE;            LayoutInflater li;            li = (LayoutInflater)getContext().getSystemService(inflater);            li.inflate(resource, toDoView, true);        } else {            toDoView = (LinearLayout)convertView;        }        TextView dateView = (TextView)toDoView.findViewById(R.id.rowDate);        TextView taskView = (TextView)toDoView.findViewById(R.id.row);        dateView.setText(dateString);        taskView.setText(taskString);        return toDoView;    }}

詳解:

1. 建構函式, 參數: 視圖內容, 資源ID, 數組;

2. 重寫getView(), 向布局視圖指派至屬性;

3. getItem, 從position擷取項目, 第一次更新需要填充視圖, 之後轉換即可;

4. 給相應的屬性複製, 從視圖中找到資源引用(findViewById), 給資源賦值;

5. 返回視圖;

4. 修改ToDoListActivity實現, 替換String為ToDoItem對象

位置: java->package->ToDoListActivity

package mzx.spike.todolist.app;import android.app.FragmentManager;import android.os.Bundle;import android.support.v7.app.ActionBarActivity;import android.view.Menu;import android.view.MenuItem;import java.util.ArrayList;public class ToDoListActivity extends ActionBarActivity implements NewItemFragment.OnNewItemAddedListener {    //使用ToDoItem對象代替String    private ToDoItemAdapter aa;    private ArrayList toDoItems;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_to_do_list);        //獲得fragment的引用        FragmentManager fm = getFragmentManager();        ToDoListFragment toDoListFragment = (ToDoListFragment)fm.findFragmentById(R.id.ToDoListFragment);        toDoItems = new ArrayList();        int resID = R.layout.todolist_item;        //三個參數        aa = new ToDoItemAdapter(this, resID, toDoItems);        toDoListFragment.setListAdapter(aa);    }    //重寫了介面的方法    public void onNewItemAdded(String newItem) {        ToDoItem newToDoItem = new ToDoItem(newItem);        toDoItems.add(0, newToDoItem);        aa.notifyDataSetChanged();    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {                // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.to_do_list, menu);        return true;    }    @Override    public boolean onOptionsItemSelected(MenuItem item) {        // Handle action bar item clicks here. The action bar will        // automatically handle clicks on the Home/Up button, so long        // as you specify a parent activity in AndroidManifest.xml.        int id = item.getItemId();        if (id == R.id.action_settings) {            return true;        }        return super.onOptionsItemSelected(item);    }}

詳解:

替換String為ToDoItem, 替換ArrayAdapter<>為ToDoItemAdapter;

5. 執行程式

代碼: http://download.csdn.net/detail/u012515223/7054943