Android - ToDoList(定制ArrayAdapter)

浏览数：32 / 时间：2015年06月11日

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

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/rowDate"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:background="@color/notepad_paper"
        android:padding="10dp"
        android:scrollbars="vertical"
        android:requiresFadingEdge="vertical"
        android:textColor="#F000"
        android:layout_alignParentRight="true"
    />

    <mzx.spike.todolist.app.ToDoListItemView
        android:id="@+id/row"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="10dp"
        android:scrollbars="vertical"
        android:requiresFadingEdge="vertical"
        android:textColor="@color/notepad_text"
        android:layout_toLeftOf="@+id/rowDate"
    />
</RelativeLayout>

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<ToDoItem> {
    int resource;

    public ToDoItemAdapter(Context context, int _resource, List<ToDoItem> 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<ToDoItem> 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<ToDoItem>();

        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;