【移动应用开发技术】怎么在Android中实现一个左滑删除列表功能

【移动应用开发技术】怎么在Android中实现一个左滑删除列表功能

怎么在Android中实现一个左滑删除列表功能？针对这个问题，这篇文章详细介绍了相对应的分析和解答，希望可以帮助更多想解决这个问题的小伙伴找到更简单易行的方法。1、布局文件view_left_slide_remove.xml包含一个RelativeLayout和TextView，RelativeLayout是实际界面，TextView是删除按钮。<?xml

version="1.0"

encoding="utf-8"?>

<RelativeLayout

xmlns:android="/apk/res/android"

android:layout_width="match_parent"

android:layout_height="40dp">

<RelativeLayout

android:id="@+id/view_content"

android:layout_width="match_parent"

android:layout_height="match_parent"

/>

<TextView

android:id="@+id/tv_remove"

android:layout_width="@dimen/left_slide_remove_width"

android:layout_height="match_parent"

android:layout_alignParentRight="true"

android:gravity="center"

android:text="删除"

android:textSize="16sp"

android:textColor="@color/white"

android:background="#ffff4b30"

android:visibility="gone"/>

</RelativeLayout>2、自定义AdapterLeftSlideRemoveAdapter类实现了BaseAdapter。在getView方法中引用了view_left_slide_remove布局，提供getSubView来导入真正的布局。OnItemRemoveListener是删除监听器。public

static

abstract

class

LeftSlideRemoveAdapter

extends

BaseAdapter

{

protected

Context

mContext;

private

OnItemRemoveListener

mListener;

public

LeftSlideRemoveAdapter(Context

context)

{

this.mContext

=

context;

}

@Override

public

final

View

getView(final

int

position,

View

convertView,

ViewGroup

parent)

{

ViewHolder

holder;

if

(convertView

==

null)

{

LayoutInflater

inflater

=

LayoutInflater.from(mContext);

convertView

=

inflater.inflate(R.layout.view_left_slide_remove,

parent,

false);

holder

=

new

ViewHolder();

holder.viewContent

=

(RelativeLayout)

convertView.findViewById(R.id.view_content);

holder.tvRmove

=

(TextView)

convertView.findViewById(R.id.tv_remove);

convertView.setTag(holder);

//

viewChild是实际的界面

holder.viewChild

=

getSubView(position,

null,

parent);

holder.viewContent.addView(holder.viewChild);

}

else

{

holder

=

(ViewHolder)

convertView.getTag();

getSubView(position,

holder.viewChild,

parent);

}

holder.tvRmove.setOnClickListener(new

View.OnClickListener(){

@Override

public

void

onClick(View

v)

{

if

(mListener

!=

null)

{

mListener.onItemRemove(position);

notifyDataSetChanged();

}

}

});

return

convertView;

}

public

abstract

View

getSubView(int

position,

View

convertView,

ViewGroup

parent);

}

private

static

class

ViewHolder

{

RelativeLayout

viewContent;

View

viewChild;

View

tvRmove;

}

public

static

interface

OnItemRemoveListener

{

public

void

onItemRemove(int

position);

}3、自定义左滑删除列表在dispatchTouchEvent方法里面捕捉MotionEvent事件。在onTouchEvent方法里面滑动界面。VelocityTracker类记录手势。Scroller类进行滑动操作。public

class

LeftSlideRemoveListView

extends

ListView

{

private

final

static

int

SNAP_VELOCITY

=

600;

private

Scroller

mScroller;

private

VelocityTracker

mVelocityTracker;

private

int

mTouchSlop;

private

boolean

mIsSlide

=

false;

private

int

mDelta

=

0;

private

int

mDownX;

private

int

mDownY;

private

int

mMaxDistence;

private

int

mSlidePosition

=

INVALID_POSITION;

private

OnItemRemoveListener

adapterListener;

private

OnItemRemoveListener

mRemoveListener

=

new

OnItemRemoveListener()

{

@Override

public

void

onItemRemove(int

position)

{

if

(adapterListener

!=

null)

{

adapterListener.onItemRemove(position);

}

clear();

mSlidePosition

=

INVALID_POSITION;

}

};

private

LeftSlideRemoveAdapter

mRemoveAdapter;

private

View

mCurrentContentView,

mCurrentRemoveView;

public

LeftSlideRemoveListView(Context

context)

{

this(context,

null);

}

public

LeftSlideRemoveListView(Context

context,

AttributeSet

attrs)

{

super(context,

attrs);

mScroller

=

new

Scroller(context);

mTouchSlop

=

ViewConfiguration.get(getContext()).getScaledTouchSlop();

mMaxDistence

=

context.getResources().getDimensionPixelSize(

R.dimen.left_slide_remove_width);

}

@Override

public

boolean

dispatchTouchEvent(MotionEvent

ev)

{

switch

(ev.getAction())

{

case

MotionEvent.ACTION_DOWN:

addVelocityTracker(ev);

if

(!mScroller.isFinished())

{

return

super.dispatchTouchEvent(ev);

}

//

起始位置，当前position

mDownX

=

(int)

ev.getX();

mDownY

=

(int)

ev.getY();

int

position

=

pointToPosition(mDownX,

mDownY);

if

(position

==

mSlidePosition)

break;

mSlidePosition

=

position;

if

(mSlidePosition

==

INVALID_POSITION

)

{

return

super.dispatchTouchEvent(ev);

}

//

恢复状态

clear();

//

获取当前界面

View

childView

=

getChildAt(mSlidePosition

-

getFirstVisiblePosition());

mCurrentContentView

=

childView.findViewById(R.id.view_content);

mCurrentRemoveView

=

childView.findViewById(R.id.tv_remove);

break;

case

MotionEvent.ACTION_MOVE:

if

(mCurrentContentView

==

null)

break;

if

(Math.abs(getScrollVelocity())

>

SNAP_VELOCITY

||

(Math.abs(ev.getX()

-

mDownX)

>

mTouchSlop

&&

Math.abs(ev.getY()

-

mDownY)

<

mTouchSlop))

{

//

开始滑动

mIsSlide

=

true;

}

break;

case

MotionEvent.ACTION_UP:

if

(mCurrentContentView

==

null

&&

mIsSlide)

break;

//

如果左滑小于4/5，按钮不显示

if

(mDelta

<

mMaxDistence

*

4

/

5)

{

mCurrentRemoveView.setVisibility(View.GONE);

scrollRight();

}

else

if

(mDelta

<

mMaxDistence)

{

scrollLeft();

}

recycleVelocityTracker();

mIsSlide

=

false;

break;

}

return

super.dispatchTouchEvent(ev);

}

@Override

public

boolean

onTouchEvent(MotionEvent

ev)

{

if

(mIsSlide

&&

mSlidePosition

!=

INVALID_POSITION)

{

final

int

action

=

ev.getAction();

int

x

=

(int)

ev.getX();

switch

(action)

{

case

MotionEvent.ACTION_MOVE:

addVelocityTracker(ev);

int

deltaX

=

mDownX

-

x;

mDownX

=

x;

mDelta

+=

deltaX;

if

(mDelta

<

0)

{

mCurrentContentView.scrollTo(0,

0);

mDelta

=

0;

mCurrentRemoveView.setVisibility(View.GONE);

}

else

if

(mDelta

>=

mMaxDistence)

{

mDelta

=

mMaxDistence;

mCurrentContentView.scrollTo(mMaxDistence,

0);

mCurrentRemoveView.setVisibility(View.VISIBLE);

mCurrentRemoveView.setTranslationX(0);

}

else

{

mCurrentContentView.scrollBy(deltaX,

0);

mCurrentRemoveView.setVisibility(View.VISIBLE);

mCurrentRemoveView.setTranslationX(mMaxDistence

-

mDelta);

}

break;

}

return

true;

}

return

super.onTouchEvent(ev);

}

//

右滑

private

void

scrollRight()

{

final

int

delta

=

mDelta;

mScroller.startScroll(delta,

0,

-delta,

0,

Math.abs(delta));

mDelta

=

0;

postInvalidate();

}

//

左滑

private

void

scrollLeft()

{

final

int

delta

=

mMaxDistence

-

mDelta;

mScroller.startScroll(mDelta,

0,

delta,

0,

Math.abs(delta));

mDelta

=

mMaxDistence;

postInvalidate();

}

@Override

public

void

computeScroll()

{

if

(mSputeScrollOffset())

{

mCurrentContentView.scrollTo(mScroller.getCurrX(),

mScroller.getCurrY());

mCurrentRemoveView.setTranslationX(mMaxDistence

-

mScroller.getCurrX());

postInvalidate();

if

(mScroller.isFinished())

{

mCurrentContentView.scrollTo(mDelta,

0);

mCurrentRemoveView.setTranslationX(0);

}

}

}

private

void

addVelocityTracker(MotionEvent

event)

{

if

(mVelocityTracker

==

null)

{

mVelocityTracker

=

VelocityTracker.obtain();

}

mVelocityTracker.addMovement(event);

}

private

int

getScrollVelocity()

{

mVelocityTputeCurrentVelocity(1000);

int

velocity

=

(int)

mVelocityTracker.getXVelocity();

return

velocity;

}

private

void

recycleVelocityTracker()

{

if

(mVelocityTracker

!=

null)

{

mVelocityTracker.recycle();

mVelocityTracker

=

null;

}

}

private

void

clear()

{

if

(mCurrentContentView

!=

null)

{

mDelta

=

0;

mCurrentContentView.scrollTo(0,

0);

mCurrentContentView

=

null;

mCurrentRemoveView.setVisibility(View.GONE);

mCurrentRemoveView

=

null;

}

}

@Override

public

void

setAdapter(ListAdapter

adapter)

{

if

(adapter

instanceof

LeftSlideRemoveAdapter)

{

super.setAdapter(adapter);

mRemoveAdapter

=

(LeftSlideRemoveAdapter)

adapter;

mRemoveAdapter.mListener

=

mRemoveListener;

}

else

{

throw

new

IllegalArgumentException("Must

be

LeftSlideRemoveAdapter");

}

}

public

void

setOnItemRemoveListener(OnItemRemoveListener

listener)

{

adapterListener

=

listener;

}

}4、测试例子ContractAdapter继承LeftSlideRemoveAdapter类。LeftSlideRemoveActivity中使用LeftSlideRemoveListView类。public

class

LeftSlideRemoveActivity

extends

Activity

{

private

List<Map<String,

String>>

mContentList

=

new

ArrayList<Map<String,

String>>();

@Override

protected

void

onCreate(Bundle

savedInstanceState)

{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_left_slide_remove);

Map<String,

String>

item

=

new

HashMap<String,

String>();

item.put("name",

"Peter");

item.put("address",

"ShangHai");

mContentList.add(item);

item

=

new

HashMap<String,

String>();

item.put("name",

"Lily");

item.put("address",

"BeiJing");

mContentList.add(item);

item

=

new

HashMap<String,

String>();

item.put("name",

"Jack");

item.put("address",

"GuangZhou");

mContentList.add(item);

item

=

new

HashMap<String,

String>();

item.put("name",

"Mike");

item.put("address",

"ShengZhen");

mContentList.add(item);

LeftSlideRemoveListView

lv

=

(LeftSlideRemoveListView)

findViewById(R.id.id_listview);

lv.setAdapter(new

ContractAdapter(this));

lv.setOnItemRemoveListener(new

LeftSlideRemoveListView.OnItemRemoveListener()

{

@Override

public

void

onItemRemove(int

position)

{

mContentList.remove(position);

}

});

}

private

class

ContractAdapter

extends

LeftSlideRemoveListView.LeftSlideRemoveAdapter

{

public

ContractAdapter(Context

context)

{

super(context);