ListView飞入加载item及滑动删除item

来源：互联网发布：南昌云迈网络做什么的编辑：程序博客网时间：2024/06/15 04:42

在listview中，可以加入动画使其效果更炫一点。这个demo修改至网上下载的一个版本，改动还算比较大。因为有动画，所以不好上演示图，不知道看到博客的各位有什么可以生成gif的工具，希望能够推荐一下。

因为是修改的别人的代码，他的demo中item数据的意义，我也不是太明白，先上一张图片：

进入程序时，呈现飞入效果。从左向右滑动item时，删除该item。

下面进入代码：

[java] view plaincopy

public class ListdemoActivity extends Activity implements OnItemClickListener, OnTouchListener{
private ArrayList<Map<String, Object>> mData;
private ListView mListView;
private MyAdapter mAdapter;
private Button mDeleteButton,mEditButton;
float x , y , upx, upy;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.history_record);
final Calendar c = Calendar.getInstance();
int year = c.get(Calendar.YEAR); //获取当前年份
int month = c.get(Calendar.MONTH);//获取当前月份
int day = c.get(Calendar.DAY_OF_MONTH);//获取当前月份的日期号码
int hour = c.get(Calendar.HOUR_OF_DAY);//获取当前的小时数
int minute = c.get(Calendar.MINUTE);//获取当前的分钟数
String minutes = "";
if (minute<10) {
minutes = "0"+minute;
}
String time_value = year+":"+month+":"+day+":"+hour+":"+ minutes;
mData = new ArrayList<Map<String, Object>>();
for (int i = 0; i < 10; i++) {
Map<String, Object> map = new HashMap<String, Object>();
map.put("image", R.drawable.ic_launcher);
map.put("maxValue", "最高值：" + i);
map.put("avgValue", "平均值：" + i);
map.put("time", time_value);
map.put("how_time", "持续时间: " + i);
map.put("last_time", "最后时间：2012-11");
map.put("isVisible", false);
mData.add(map);
}
mAdapter = new MyAdapter(this);
mListView = (ListView)findViewById(R.id.list);
mListView.setCacheColorHint(Color.TRANSPARENT); // 设置背景透明度
mListView.setAdapter(mAdapter);
mListView.setOnTouchListener(this);
// mListView.setOnItemClickListener(this);
mListView.setLayoutAnimation(getListAnim());
}

在onCreate()方法里面，主要是初始化控件和数据。x、y、upx、upy是onTouch时判定位移的参数，以上代码比较简单。

下面就是mListView.setOnTouchListener(this)里面的内容，该activity继承了OnTouchListener接口，下面是它的实现：

[java] view plaincopy

@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
x = event.getX();
y = event.getY();
}
if (event.getAction() == MotionEvent.ACTION_UP) {
upx = event.getX();
upy = event.getY();
int position1 = ((ListView) v).pointToPosition((int) x, (int) y);
int position2 = ((ListView) v).pointToPosition((int) upx,(int) upy);
if (position1 == position2 && Math.abs(x - upx) > 10) {
View view = ((ListView) v).getChildAt(position1);
removeListItem(view, position1);
}
}
return false;
}

判断是否滑动，如果滑动，调用removeListItem方法：

[java] view plaincopy

protected void removeListItem(View rowView, final int positon) {
final Animation animation = (Animation) AnimationUtils.loadAnimation(rowView.getContext(), R.anim.item_anim);
animation.setAnimationListener(new AnimationListener() {
public void onAnimationStart(Animation animation) {}
public void onAnimationRepeat(Animation animation) {}
public void onAnimationEnd(Animation animation) {
mData.remove(positon);
mAdapter.notifyDataSetChanged();
animation.cancel();
}
});
rowView.startAnimation(animation);
}

在代码中，我们可以看到在onAnimationEnd()中，是删除了数据。同理，当你想在动画开始时进行一些操作，就可以在回调函数onAnimationStart中进行。另外，方法里使用了动画：

item_anim.xml:

[java] view plaincopy

<?xml version="1.0" encoding="utf-8"?>
<translate xmlns:android="http://schemas.android.com/apk/res/android"
android:duration="800"
android:fromXDelta="0"
android:fromYDelta="0"
android:toXDelta="800"
android:toYDelta="0" />

下面再看飞入效果，mListView.setLayoutAnimation(getListAnim())：

也可以在listView的xml中：android:layoutAnimation="@anim/item_anim"这样定义

[java] view plaincopy

private LayoutAnimationController getListAnim() {
AnimationSet set = new AnimationSet(true);
Animation animation = new AlphaAnimation(0.0f, 1.0f);
animation.setDuration(300);
set.addAnimation(animation);
animation = new TranslateAnimation(Animation.RELATIVE_TO_SELF, 0.0f,
Animation.RELATIVE_TO_SELF, 0.0f, Animation.RELATIVE_TO_SELF,
-1.0f, Animation.RELATIVE_TO_SELF, 0.0f);
animation.setDuration(500);
set.addAnimation(animation);
LayoutAnimationController controller = new LayoutAnimationController(
set, 0.5f);
return controller;
}

使用LayoutAnimation实现。

在代码中，屏蔽掉了mListView.setOnItemClickListener(this)这行代码，因为它对onTouch会造成干扰，当然它的方法中是弹出一个Dialog进行删除操作：

[java] view plaincopy

@Override
public void onItemClick(AdapterView<?> parent, View view, final int position,
long id) {
new AlertDialog.Builder(ListdemoActivity.this).setTitle("标题")
.setMessage("提示内容").setPositiveButton("删除",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int whichButton) {
mData.remove(position);
mAdapter.notifyDataSetChanged();
}
}).setNegativeButton("取消", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
System.out.println("你好啊");
}
}).show();
}

比较重要，但是又最常见的自定义Adapter：

[java] view plaincopy

class ViewHolder {
public TextView maxValue;
public Button del_btn;
public TextView how_time;
public TextView last_time;
public TextView avgValue;
public ImageView image;
public boolean isVisible = true;
}
public class MyAdapter extends BaseAdapter {
private Context mContext;
private MyAdapter(Context context) {
mContext = context;
}
public int getCount() {
return mData.size();
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
if(convertView == null) {
holder = new ViewHolder();
LayoutInflater inflater = LayoutInflater.from(mContext);
convertView = inflater.inflate(R.layout.record_info, null);
holder.del_btn = (Button) convertView.findViewById(R.id.del);
holder.how_time = (TextView) convertView.findViewById(R.id.how_time);
holder.last_time = (TextView) convertView.findViewById(R.id.last_time);
holder.avgValue = (TextView) convertView.findViewById(R.id.avgValue);
holder.image = (ImageView)convertView.findViewById(R.id.image);
holder.maxValue = (TextView)convertView.findViewById(R.id.maxValue);
convertView.setTag(holder);
} else {
holder = (ViewHolder)convertView.getTag();
}
holder.image.setBackgroundResource((Integer)mData.get(position).get("image"));
holder.del_btn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
mData.remove(position);
mAdapter.notifyDataSetChanged();
}
});
holder.how_time.setText((String)(mData.get(position).get("how_time")));
holder.last_time.setText((String)(mData.get(position).get("last_time")));
holder.avgValue.setText((String)(mData.get(position).get("avgValue")));
holder.maxValue.setText((String)(mData.get(position).get("maxValue")));
return convertView;
}
}

这个相信都写烂了。

最后：代码下载地址：http://download.csdn.net/detail/aomandeshangxiao/4696742

晚安！

好吧，其实上面的代码是有问题的，就是下面的一位童鞋提到的问题，当滑动到最后几项，选择滑动删除的时候，会报空指针异常，为什么会出现这种情况？我在打印的log中发现listView只是会创建前5个View，后面看到显示的View，均是重用。当尝试从ListView中获取第十个item的View的时候，肯定会报空指针异常。

所以在onTouch方法中做了一下修改：

[java] view plaincopy

@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
x = event.getX();
y = event.getY();
}
if (event.getAction() == MotionEvent.ACTION_UP) {
upx = event.getX();
upy = event.getY();
int position1 = ((ListView) v).pointToPosition((int) x, (int) y);
int position2 = ((ListView) v).pointToPosition((int) upx,(int) upy);
int FirstVisiblePosition = mListView.getFirstVisiblePosition();
if (position1 == position2 && Math.abs(x - upx) > 10) {
View view = ((ListView) v).getChildAt(position1);
if (view == null) {
view = ((ListView) v).getChildAt(position1 - FirstVisiblePosition);
}
removeListItem(view, position1);
}
}
return false;
}

获取选中项重用的那个View，然后执行动画。在最后要感谢立涛和方涛对我的帮助！！！