ListView與Button的共存問題解決——ListView中的Button Click事件

 ListView和其它能觸發點擊事件的widget無法一起正常工作的原因是加入其它widget後,ListView的itemclick事件將無法觸發,被其它widget的click事件屏蔽。

 

首先,說明一下,ListView中每一行包括以下三項:

 

  一個ImageView,一個TextView,一個ImageButton,依次排開。

 

以下是layout的內容,分爲兩部分:

res/layout/main.xml

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

<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="fill_parent"android:layout_height="fill_parent"

    android:padding="10dip" android:orientation="vertical">

 

    <ListView android:id="@id/android:list"android:layout_width="fill_parent"

        android:layout_height="fill_parent" />

</LinearLayout>

 

 

因爲繼承了ListActivity,所以ListView的id設置爲"@id/android:list"是必須的

res/layout/lvitem.xml

 

注意:

 

在<RelativeLayout>中

 

android:descendantFocusability="blocksDescendants"

 

和<ImageButton>中

 

android:focusable="false"

 

這兩項的設置很關鍵,如果不設置,將導致ListView的ItemClick事件將無法觸發,該事件被ImageButton的click事件屏蔽了。

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

<RelativeLayout

  xmlns:android="http://schemas.android.com/apk/res/android"

  android:layout_width="fill_parent"

  android:layout_height="wrap_content"

  android:padding="5dip"

  android:descendantFocusability="blocksDescendants" >

  

  <ImageView

      android:id="@+id/ItemImage"

    android:layout_width="wrap_content"

    android:layout_height="wrap_content"

    android:padding="5dip"

  />

  

  

  <!--

      把按鈕背景設置爲透明:    android:background="#00000000"

      把按鈕背景設置爲半透明:    android:background="#e0000000"

      -->

  <ImageButton

     android:id="@+id/ItemCloseWin"

     

     android:layout_alignParentRight="true"

     android:layout_alignTop="@+id/ItemWinName"

      android:layout_alignBottom="@+id/ItemWinName"

      android:layout_width="wrap_content"

      android:layout_height="wrap_content"

      

      android:background="#e0000000"

      android:gravity="left|center_vertical"

      android:focusable="false"

      android:src="@android:drawable/ic_menu_close_clear_cancel"

  />

  

  <TextView

      android:id="@+id/ItemWinName"

      

      android:layout_toRightOf="@+id/ItemImage"

      android:layout_toLeftOf="@+id/ItemCloseWin"

      android:layout_alignTop="@+id/ItemImage"

      android:layout_alignBottom="@+id/ItemImage"

      android:layout_width="wrap_content"

      android:layout_height="wrap_content"

      

      android:gravity="left|center_vertical"

      android:textSize="20dip"

      android:text="title"

  />

    

   

</RelativeLayout>

 

接下來,我們看看繼承ListActivity的實現

 

在lvWithButtonExt中,爲了能處理ImageButton的click事件,我繼承了BaseAdapter類,並重新實現了getView()接口,在其中加入了Button的clicklistener,詳見lvButtonAdapter類的實現。

 

public class lvWithButtonExt extendsListActivity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

 

        //關聯Layout中的ListView

        ListView vncListView = (ListView)findViewById(android.R.id.list);

        

        //生成動態數組,加入數據

        ArrayList<HashMap<String, Object>> remoteWindowItem = newArrayList<HashMap<String, Object>>();

        for(int i=0;i<10;i++)

        {

            HashMap<String, Object> map = new HashMap<String, Object>();

            map.put("ItemImage", R.drawable.firefox);//圖像資源的ID

            map.put("ItemWinName", "Window ID "+i);

            map.put("ItemCloseWin",android.R.drawable.ic_menu_close_clear_cancel);

            remoteWindowItem.add(map);

        }

        

      //生成適配器的Item和動態數組對應的元素

        lvButtonAdapter listItemAdapter = new lvButtonAdapter(

            this,

            remoteWindowItem,//數據源

            R.layout.lvitem,//ListItem的XML實現

 

            //動態數組與ImageItem對應的子項

            new String[] {"ItemImage","ItemWinName","ItemCloseWin"},

            //ImageItem的XML文件裏面的一個ImageView,兩個TextView ID

            new int[] {R.id.ItemImage,R.id.ItemWinName,R.id.ItemCloseWin}

        );

        

        vncListView.setAdapter(listItemAdapter);

    }

 

    @Override

    protected void onListItemClick(ListView l, View v, int position, longid) {

        // TODO Auto-generated method stub

        super.onListItemClick(l, v, position, id);

        l.getItemAtPosition(position);

    }

}

 

接下來,我們看看lvButtonAdapter的實現

 

爲了響應按鈕的點擊事件,首先要記錄按鈕的位置,然後爲按鈕設置clicklistener。

 

在重新實現的getView()接口中,我使用了lvButtonListener監聽類,在構造函數中,記錄行號,以便在OnClick接口中能準確的定位按鈕所在的位置,進而對相應的行進行處理。

public class lvButtonAdapter extendsBaseAdapter {

    private class buttonViewHolder {

        ImageView appIcon;

        TextView appName;

        ImageButton buttonClose;

    }

    

    private ArrayList<HashMap<String, Object>> mAppList;

    private LayoutInflater mInflater;

    private Context mContext;

    private String[] keyString;

    private int[] valueViewID;

    private buttonViewHolder holder;

    

    public lvButtonAdapter(Context c, ArrayList<HashMap<String,Object>> appList, int resource,

            String[] from, int[] to) {

        mAppList = appList;

        mContext = c;

        mInflater = (LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        keyString = new String[from.length];

        valueViewID = new int[to.length];

        System.arraycopy(from, 0, keyString, 0, from.length);

        System.arraycopy(to, 0, valueViewID, 0, to.length);

    }

    

    @Override

    public int getCount() {

        return mAppList.size();

    }

 

    @Override

    public Object getItem(int position) {

        return mAppList.get(position);

    }

 

    @Override

    public long getItemId(int position) {

        return position;

    }

 

    public void removeItem(int position){

        mAppList.remove(position);

        this.notifyDataSetChanged();

    }

    

    @Override

    public View getView(int position, View convertView, ViewGroup parent) {

        if (convertView != null) {

            holder = (buttonViewHolder) convertView.getTag();

        } else {

            convertView = mInflater.inflate(R.layout.lvitem, null);

            holder = new buttonViewHolder();

            holder.appIcon = (ImageView)convertView.findViewById(valueViewID[0]);

            holder.appName = (TextView)convertView.findViewById(valueViewID[1]);

            holder.buttonClose =(ImageButton)convertView.findViewById(valueViewID[2]);

            convertView.setTag(holder);

        }

        

        HashMap<String, Object> appInfo = mAppList.get(position);

        if (appInfo != null) {

            String aname = (String) appInfo.get(keyString[1]);

            int mid = (Integer)appInfo.get(keyString[0]);

            int bid = (Integer)appInfo.get(keyString[2]);

            holder.appName.setText(aname);

            holder.appIcon.setImageDrawable(holder.appIcon.getResources().getDrawable(mid));

            holder.buttonClose.setImageDrawable(holder.buttonClose.getResources().getDrawable(bid));

            holder.buttonClose.setOnClickListener(new lvButtonListener(position));

        }       

        return convertView;

    }

 

    class lvButtonListener implements OnClickListener {

        private int position;

 

        lvButtonListener(int pos) {

            position = pos;

        }

        

        @Override

        public void onClick(View v) {

            int vid=v.getId();

            if (vid == holder.buttonClose.getId())

                removeItem(position);

        }

    }

}

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