Android - ToDoList(fragment) 详解

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ToDoList(fragment) 详解

本文地址: http://blog.csdn.net/caroline_wendy/article/details/21246963

ToDoList做为Android的经典练习, 参考: http://blog.csdn.net/caroline_wendy/article/details/21223995

Fragment(碎片) 可以灵活地从一个活动的Activity上添加或删除Fragment, 有良好的用户体验;

下面是Fragment的具体设计:

1. 创建new_item_fragment的资源文件:

位置: res->new_item_fragment.xml

<?xml version="1.0" encoding="utf-8"?><EditText xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/myEditText"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:hint="@string/addItemHint"    android:contentDescription="@string/addItemContentDescription"/>

包含一个EditText控件;

2. 创建NewItemFragment的逻辑实现:

位置: java->package->NewItemFragment.java

package mzx.spike.todolist.app;import android.app.Activity;import android.app.Fragment;import android.os.Bundle;import android.view.KeyEvent;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.EditText;/** * Created by C.L.Wang on 14-3-14. */public class NewItemFragment extends Fragment{    private  OnNewItemAddedListener onNewItemAddedListener;    //监听事件    public interface OnNewItemAddedListener {        public void onNewItemAdded(String newItem);    }    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container,                             Bundle savedInstanceState) {        View view = inflater.inflate(R.layout.new_item_fragment, container, false);        final EditText myEditText = (EditText)view.findViewById(R.id.myEditText);        //监听事件        myEditText.setOnKeyListener(new View.OnKeyListener() {            @Override            public boolean onKey(View view, int i, KeyEvent keyEvent) {                if (keyEvent.getAction() == KeyEvent.ACTION_DOWN)                    if ((i == KeyEvent.KEYCODE_DPAD_CENTER) ||                       (i == KeyEvent.KEYCODE_ENTER)) {                        String newItem = myEditText.getText().toString();                        onNewItemAddedListener.onNewItemAdded(newItem);                        myEditText.setText("");                        return true;                    }                return false;            }        });        return view;    }    //绑定到Activity    public void onAttach(Activity activity) {        super.onAttach(activity);        try {            onNewItemAddedListener = (OnNewItemAddedListener)activity;        } catch (ClassCastException e) {            throw new ClassCastException(activity.toString() + " must implement OnNewItemAddedListener");        }    }}

详解:

1. 继承Fragment类;

2. 监听接口(interface OnNewItemListener), 包含一个监听方法(onNewItemAdded), 然后实现一个实例;

3. 创建视图(onCreateView), 需要返回一个视图(View);

4. 填充一个视图, 调用inflater.inflate()函数, 绑定fragment的资源文件;

5. 获得控件的引用, view.findViewById(), 得到myEditText的引用;

6. 监听事件, 监听myEditText的输入内容, 传递给接口的内容(new Item);

7. 使用onAttach()函数, 绑定Acitivity之后, 获得activity的引用;

3. 创建ToDoListFragment的逻辑实现:

位置: java->package->ToDoListFragment.java

package mzx.spike.todolist.app;import android.app.ListFragment;/** * Created by C.L.Wang on 14-3-14. */public class ToDoListFragment extends ListFragment{}

继承ListFragment;

4. 创建activity_to_do_list资源文件, 即Activity资源文件:

位置: res->layout->activity_to_do_list.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:orientation="vertical"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:paddingBottom="@dimen/activity_vertical_margin"    tools:context="mzx.spike.todolist.app.ToDoListActivity">    <fragment android:name="mzx.spike.todolist.app.NewItemFragment"        android:id="@+id/NewItemFragment"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:hint="@string/addItemHint"        android:contentDescription="@string/addItemContentDescription"    />    <fragment android:name="mzx.spike.todolist.app.ToDoListFragment"        android:id="@+id/ToDoListFragment"        android:layout_width="match_parent"        android:layout_height="wrap_content"    /></LinearLayout>

LinearLayout包含两个fragment结点, 需要提供android:name的参数, 实现;

5. 创建ToDoListActivityt的逻辑实现, 即Activity的逻辑实现:

位置: java->package->ToDoListActivityt.java

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 android.widget.ArrayAdapter;import java.util.ArrayList;public class ToDoListActivity extends ActionBarActivity implements NewItemFragment.OnNewItemAddedListener {    private ArrayAdapter<String> aa;    private ArrayList<String> 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<String>();        //三个参数        aa = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, toDoItems);        toDoListFragment.setListAdapter(aa);    }    //重写了接口的方法    public void onNewItemAdded(String newItem) {        toDoItems.add(newItem);        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:

1. 继承监听接口(OnNewItemAddedListener);

2. ArrayList类型数据, 和适配器(ArrayAdapter);

3. 通过findFragmentById(), 获得ToDoListFragment的引用;

4. 把toDoItem绑定适配器, ToDoListFragment设置适配器(setListAdapter);

5. 实现接口的方法, 传递至toDoItems, 通知适配器更改(notifyDataSetChanged);

6. 执行程序:

其他文件参考: http://blog.csdn.net/caroline_wendy/article/details/21223995

下载地址: http://download.csdn.net/detail/u012515223/7042137

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