Android - ToDoList(fragment) 详解

ToDoList(fragment) 详解


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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


Android - ToDoList(fragment) 详解

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Android - ToDoList(fragment) 详解

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