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我开发了一个应用程序，我在其中使用水平ListView显示内容（实际上这个内容适用于标题）。我使用了两个按钮来左右滚动以查看更多内容。我对此感到困惑，任何人都可以建议我如何解决这个问题呢 ？谢谢

Horizo​​ntalListView的代码

public class HorizontialListView extends AdapterView<ListAdapter> {

    public boolean mAlwaysOverrideTouch = true;
    protected ListAdapter mAdapter;
    private int mLeftViewIndex = -1;
    private int mRightViewIndex = 0;
    protected int mCurrentX;
    protected int mNextX;
    private int mMaxX = Integer.MAX_VALUE;
    private int mDisplayOffset = 0;
    protected Scroller mScroller;
    private GestureDetector mGesture;
    private Queue<View> mRemovedViewQueue = new LinkedList<View>();
    private OnItemSelectedListener mOnItemSelected;
    private OnItemClickListener mOnItemClicked;
    private boolean mDataChanged = false;

    public HorizontialListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initView();
    }

    private synchronized void initView() {
        mLeftViewIndex = -1;
        mRightViewIndex = 0;
        mDisplayOffset = 0;
        mCurrentX = 0;
        mNextX = 0;
        mMaxX = Integer.MAX_VALUE;
        mScroller = new Scroller(getContext());
        mGesture = new GestureDetector(getContext(), mOnGesture);
    }

    @Override
    public void setOnItemSelectedListener(
            AdapterView.OnItemSelectedListener listener) {
        mOnItemSelected = listener;
    }

    @Override
    public void setOnItemClickListener(AdapterView.OnItemClickListener listener) {
        mOnItemClicked = listener;
    }

    private DataSetObserver mDataObserver = new DataSetObserver() {

        @Override
        public void onChanged() {
            synchronized (HorizontialListView.this) {
                mDataChanged = true;
            }
            invalidate();
            requestLayout();
        }

        @Override
        public void onInvalidated() {
            reset();
            invalidate();
            requestLayout();
        }

    };

    @Override
    public ListAdapter getAdapter() {
        return mAdapter;
    }

    @Override
    public View getSelectedView() {
        // TODO: implement
        return null;
    }

    @Override
    public void setAdapter(ListAdapter adapter) {
        if (mAdapter != null) {
            mAdapter.unregisterDataSetObserver(mDataObserver);
        }
        mAdapter = adapter;
        mAdapter.registerDataSetObserver(mDataObserver);
        reset();
    }

    private synchronized void reset() {
        initView();
        removeAllViewsInLayout();
        requestLayout();
    }

    @Override
    public void setSelection(int position) {
        // TODO: implement
    }

    private void addAndMeasureChild(final View child, int viewPos) {
        LayoutParams params = child.getLayoutParams();
        if (params == null) {
            params = new LayoutParams(LayoutParams.FILL_PARENT,
                    LayoutParams.FILL_PARENT);
        }

        addViewInLayout(child, viewPos, params, true);
        child.measure(
                MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.AT_MOST),
                MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.AT_MOST));
    }

    @Override
    protected synchronized void onLayout(boolean changed, int left, int top,
            int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);

        if (mAdapter == null) {
            return;
        }

        if (mDataChanged) {
            int oldCurrentX = mCurrentX;
            initView();
            removeAllViewsInLayout();
            mNextX = oldCurrentX;
            mDataChanged = false;
        }

        if (mScroller.computeScrollOffset()) {
            int scrollx = mScroller.getCurrX();
            mNextX = scrollx;
        }

        if (mNextX < 0) {
            mNextX = 0;
            mScroller.forceFinished(true);
        }
        if (mNextX > mMaxX) {
            mNextX = mMaxX;
            mScroller.forceFinished(true);
        }

        int dx = mCurrentX - mNextX;

        removeNonVisibleItems(dx);
        fillList(dx);
        positionItems(dx);

        mCurrentX = mNextX;

        if (!mScroller.isFinished()) {
            post(new Runnable() {
                @Override
                public void run() {
                    requestLayout();
                }
            });

        }
    }

    private void fillList(final int dx) {
        int edge = 0;
        View child = getChildAt(getChildCount() - 1);
        if (child != null) {
            edge = child.getRight();
        }
        fillListRight(edge, dx);

        edge = 0;
        child = getChildAt(0);
        if (child != null) {
            edge = child.getLeft();
        }
        fillListLeft(edge, dx);

    }

    private void fillListRight(int rightEdge, final int dx) {
        while (rightEdge + dx < getWidth()
                && mRightViewIndex < mAdapter.getCount()) {

            View child = mAdapter.getView(mRightViewIndex,
                    mRemovedViewQueue.poll(), this);
            addAndMeasureChild(child, -1);
            rightEdge += child.getMeasuredWidth();

            if (mRightViewIndex == mAdapter.getCount() - 1) {
                mMaxX = mCurrentX + rightEdge - getWidth();
            }
            mRightViewIndex++;
        }

    }

    private void fillListLeft(int leftEdge, final int dx) {
        while (leftEdge + dx > 0 && mLeftViewIndex >= 0) {
            View child = mAdapter.getView(mLeftViewIndex,
                    mRemovedViewQueue.poll(), this);
            addAndMeasureChild(child, 0);
            leftEdge -= child.getMeasuredWidth();
            mLeftViewIndex--;
            mDisplayOffset -= child.getMeasuredWidth();
        }
    }

    private void removeNonVisibleItems(final int dx) {
        View child = getChildAt(0);
        while (child != null && child.getRight() + dx <= 0) {
            mDisplayOffset += child.getMeasuredWidth();
            mRemovedViewQueue.offer(child);
            removeViewInLayout(child);
            mLeftViewIndex++;
            child = getChildAt(0);

        }

        child = getChildAt(getChildCount() - 1);
        while (child != null && child.getLeft() + dx >= getWidth()) {
            mRemovedViewQueue.offer(child);
            removeViewInLayout(child);
            mRightViewIndex--;
            child = getChildAt(getChildCount() - 1);
        }
    }

    private void positionItems(final int dx) {
        if (getChildCount() > 0) {
            mDisplayOffset += dx;
            int left = mDisplayOffset;
            for (int i = 0; i < getChildCount(); i++) {
                View child = getChildAt(i);
                int childWidth = child.getMeasuredWidth();
                child.layout(left, 0, left + childWidth,
                        child.getMeasuredHeight());
                left += childWidth;
            }
        }
    }

    public synchronized void scrollTo(int x) {
        mScroller.startScroll(mNextX, 0, x - mNextX, 0);
        requestLayout();
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        boolean handled = mGesture.onTouchEvent(ev);
        return handled;
    }

    protected boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
            float velocityY) {
        synchronized (HorizontialListView.this) {
            mScroller.fling(mNextX, 0, (int) -velocityX, 0, 0, mMaxX, 0, 0);
        }
        requestLayout();

        return true;
    }

    protected boolean onDown(MotionEvent e) {
        mScroller.forceFinished(true);
        return true;
    }

    private OnGestureListener mOnGesture = new GestureDetector.SimpleOnGestureListener() {

        @Override
        public boolean onDown(MotionEvent e) {
            return HorizontialListView.this.onDown(e);
        }

        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                float velocityY) {
            return HorizontialListView.this.onFling(e1, e2, velocityX,
                    velocityY);
        }

        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2,
                float distanceX, float distanceY) {

            synchronized (HorizontialListView.this) {
                mNextX += (int) distanceX;
            }
            requestLayout();

            return true;
        }

        @Override
        public boolean onSingleTapConfirmed(MotionEvent e) {
            Rect viewRect = new Rect();
            for (int i = 0; i < getChildCount(); i++) {
                View child = getChildAt(i);
                int left = child.getLeft();
                int right = child.getRight();
                int top = child.getTop();
                int bottom = child.getBottom();
                viewRect.set(left, top, right, bottom);
                if (viewRect.contains((int) e.getX(), (int) e.getY())) {
                    if (mOnItemClicked != null) {
                        mOnItemClicked.onItemClick(HorizontialListView.this,
                                child, mLeftViewIndex + 1 + i,
                                mAdapter.getItemId(mLeftViewIndex + 1 + i));
                    }
                    if (mOnItemSelected != null) {
                        mOnItemSelected.onItemSelected(
                                HorizontialListView.this, child, mLeftViewIndex
                                        + 1 + i,
                                mAdapter.getItemId(mLeftViewIndex + 1 + i));
                    }
                    break;
                }

            }
            return true;
        }

    };

}

xml代码

<com.ui.HorizontialListView
            android:id="@+id/listview"
            android:layout_width="fill_parent"
            android:layout_height="30dp"
            android:layout_centerInParent="true"
            android:layout_toLeftOf="@+id/rightcorv"
            android:layout_toRightOf="@+id/leftcorv" />
4

4 回答 4

2 
private void startScroll(AbsListView view)
{
    try
    {
        Field field = android.widget.AbsListView.class.getDeclaredField("mFlingRunnable");
        field.setAccessible(true);
        Object flingRunnable = field.get(view);
        if (flingRunnable != null)
        {
            Method method = Class.forName("android.widget.AbsListView$FlingRunnable").getDeclaredMethod("endFling");
            method.setAccessible(true);
            method.invoke(flingRunnable);
        }
    }
    catch (Exception e) {}
}

Just call startScroll(myListView); when you need to start scroll.
于 2014-08-21T11:04:49.620 回答
1

试试这个代码，这可能会对你有所帮助。

int index = mList.getFirstVisiblePosition();
View view = mList.getChildAt(0);
int top = (view == null) ? 0 : view.getTop();

// restore
mList.setSelectionFromTop(index, top);
于 2012-09-20T13:05:10.713 回答
0

您可能希望使用 setSelection() 方法，而不是每次将列表滚动 100 像素。向下滚动时增加选择，向上滚动时减少选择。这将确保单击正确的项目。希望这可以帮助。

于 2012-09-20T12:57:26.677 回答
0

对于上一个，请参阅 BtnPrev，对于下一个，请参阅 btnNext R.id.lv 是您的列表视图的 id。

Button btnPrev = (Button) findViewById(R.id.button1);
    btnPrev.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            ListView lv = (ListView) findViewById(R.id.lv);

            int firstVisibleItem = lv.getFirstVisiblePosition();
            int lastVisibleCount = lv.getLastVisiblePosition();
            if (firstVisibleItem != 0) {
                int count1 = firstVisibleItem
                        - (lastVisibleCount - firstVisibleItem);
                if (count1 < 0) {
                    lv.setSelection(0);
                }

                else {
                    lv.setSelection(count1);
                }
            }

        }
    });

    Button btnNext = (Button) findViewById(R.id.button2);
    btnNext.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            ListView lv = (ListView) findViewById(R.id.lv);
            int count = lv.getCount();
            int firstVisibleItem = lv.getFirstVisiblePosition();
            int lastVisibleCount = lv.getLastVisiblePosition();
            if (lastVisibleCount != count) {
                int count1 = lastVisibleCount
                        + (lastVisibleCount - firstVisibleItem);
                if (count1 > count) {
                    lv.setSelection(count);
                } else {
                    lv.setSelection(count1);
                }
            }

        }
    });
于 2012-09-20T13:21:17.030 回答