ToDoList(定制ArrayAdapter)
本文地址: http://blog.csdn.net/caroline_wendy/article/details/21401907
前置项目参见: http://blog.csdn.net/caroline_wendy/article/details/21330733
环境: Android Studio 0.5.1
ArrayAdapter使用泛型(模板)把Adapter视图绑定到一个指定类的对象的数组;
定制ArrayAdapter需要重写getView()方法, 向布局视图分配对象属性;
ToDoList在每一项后面添加时间, 需要创建ToDoItem对象, 使用定制的ArrayAdapter;
步骤:
1. 创建ToDoItem对象
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;
}
}
详解:
两个私有变量, 存储任务(task)和日期(date), 两种构造方法, 重写了toString方法;
2. 修改todolist_item布局(xml)
位置: res->layout->todolist_item.xml
详解:
1. 使用RelativeLayout(相关)布局;
2. TextView存储日期(date);
3. ToDoListItemView(定制, java)存储任务(task);
4. layout_toLeftOf属性, 表示位于某个视图的左边;
5. fadingEdge标签, 褪去边缘, 遗弃, 被requiresFadingEdge标签代替;
3. 创建ToDoItemAdapter, 定制适配器
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;
}
}
详解:
1. 构造函数, 参数: 视图内容, 资源ID, 数组;
2. 重写getView(), 向布局视图分配对象属性;
3. getItem, 从position获取项目, 第一次更新需要填充视图, 之后转换即可;
4. 给相应的属性复制, 从视图中找到资源引用(findViewById), 给资源赋值;
5. 返回视图;
4. 修改ToDoListActivity实现, 替换String为ToDoItem对象
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对象代替String
private ToDoItemAdapter aa;
private ArrayList toDoItems;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_to_do_list);
//获得fragment的引用
FragmentManager fm = getFragmentManager();
ToDoListFragment toDoListFragment = (ToDoListFragment)fm.findFragmentById(R.id.ToDoListFragment);
toDoItems = new ArrayList();
int resID = R.layout.todolist_item;
//三个参数
aa = new ToDoItemAdapter(this, resID, toDoItems);
toDoListFragment.setListAdapter(aa);
}
//重写了接口的方法
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);
}
}
详解:
替换String为ToDoItem, 替换ArrayAdapter为ToDoItemAdapter;
