我们是否有任何方式可以一次只滚动ListView个项目。
就像当你向上滑动它只会滚动一个项目而不是正常滚动类似向下滚动只有一个项目向下移动。
请帮助！
这是我的代码：
public class ListViewTestExample extends Activity {
ListView listView;
private GestureDetectorCompat mDetector;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_list_view_test);
mDetector = new GestureDetectorCompat(this, new MyGestureListener());
// Grid ListView object from XML
listView = (ListView) findViewById(R.id.list);
mDetector = new GestureDetectorCompat(this, new MyGestureListener());
// Defined Array values to show in ListView
String[] values = new String[] { "Android List View",
"Adapter implementation", "Simple List View In Android",
"Create List View Android", "Android Example",
"List View Source Code", "List View Array Adapter",
"Android Example List View" };
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, android.R.id.text1, values);
listView.setAdapter(adapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public boolean onTouchEvent(MotionEvent event) {
this.mDetector.onTouchEvent(event);
return super.onTouchEvent(event);
}
class MyGestureListener extends GestureDetector.SimpleOnGestureListener {
Context context = getApplicationContext();
public boolean onDown(MotionEvent event) {
return true;
}
public void onLongPress(MotionEvent event) {
Toast.makeText(context, "Long Press", Toast.LENGTH_SHORT).show();
}
public boolean onFling(MotionEvent event1, MotionEvent event2,
float velocityX, float velocityY) {
float sensitvity = 50;
// TODO Auto-generated method stub
if ((event1.getX() - event2.getX()) > sensitvity) {
Toast.makeText(context, "Swipe Left", Toast.LENGTH_SHORT)
.show();
} else if ((event2.getX() - event1.getX()) > sensitvity) {
Toast.makeText(context, "Swipe Right", Toast.LENGTH_SHORT)
.show();
}
if ((event1.getY() - event2.getY()) > sensitvity) {
if (event2.getPressure() > event1.getPressure()) {
Toast.makeText(context, "Swipe Up + Hold",
Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(context, "Swipe Up", Toast.LENGTH_SHORT).show();
}
} else if ((event2.getY() - event1.getY()) > sensitvity) {
if (event2.getPressure() > event1.getPressure()) {
Toast.makeText(context, "Swipe Down + Hold",
Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(context, "Swipe Down", Toast.LENGTH_SHORT).show();
}
}
return true;
}
public boolean onSingleTapConfirmed(MotionEvent event) {
Toast.makeText(context, "Single Tap Confirmed", Toast.LENGTH_SHORT)
.show();
return true;
}
public boolean onDoubleTap(MotionEvent event) {
Toast.makeText(context, "Double Tap Confirmed", Toast.LENGTH_SHORT).show();
return true;
}
}
}
答案 0 :(得分：15)
我知道现在这是一个老帖子，但我已经搜索了网络，并没有真正找到解决方案。所以我找到了一个适合我的解决方案。您需要创建自定义ListView并覆盖dispatchTouchEvent函数。我的版本检查用户是否以最小速度轻弹，如果他们有光滑滚动到下一个项目。如果在此速度下，则检查项目是否超过一半，然后进行平滑滚动。否则返回当前项目。此代码假定该项填充视图。
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.widget.ListView;
/**
* Created by bradj on 11/12/13.
*/
public class SingleScrollListView extends ListView
{
private boolean mSingleScroll = false;
private VelocityTracker mVelocity = null;
final private float mEscapeVelocity = 2000.0f;
final private int mMinDistanceMoved = 20;
private float mStartY = 0;
public SingleScrollListView(Context context)
{
super(context);
}
public SingleScrollListView(Context context, AttributeSet attrs)
{
super(context, attrs);
}
public SingleScrollListView(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
}
public void setSingleScroll(boolean aSingleScroll) { mSingleScroll = aSingleScroll; }
public int getVerticalScrollOffset() { return getFirstVisiblePosition(); }
@Override
public boolean dispatchTouchEvent(MotionEvent aMotionEvent)
{
if (aMotionEvent.getAction() == MotionEvent.ACTION_DOWN)
{
if (mSingleScroll && mVelocity == null)
mVelocity = VelocityTracker.obtain();
mStartY = aMotionEvent.getY();
return super.dispatchTouchEvent(aMotionEvent);
}
if (aMotionEvent.getAction() == MotionEvent.ACTION_UP)
{
if (mVelocity != null)
{
if (Math.abs(aMotionEvent.getY() - mStartY) > mMinDistanceMoved)
{
mVelocity.computeCurrentVelocity(1000);
float velocity = mVelocity.getYVelocity();
if (aMotionEvent.getY() > mStartY)
{
// always lock
if (velocity > mEscapeVelocity)
smoothScrollToPosition(getFirstVisiblePosition());
else
{
// lock if over half way there
View view = getChildAt(0);
if (view != null)
{
if (view.getBottom() >= getHeight() / 2)
smoothScrollToPosition(getFirstVisiblePosition());
else
smoothScrollToPosition(getLastVisiblePosition());
}
}
}
else
{
if (velocity < -mEscapeVelocity)
smoothScrollToPosition(getLastVisiblePosition());
else
{
// lock if over half way there
View view = getChildAt(1);
if (view != null)
{
if (view.getTop() <= getHeight() / 2)
smoothScrollToPosition(getLastVisiblePosition());
else
smoothScrollToPosition(getFirstVisiblePosition());
}
}
}
}
mVelocity.recycle();
}
mVelocity = null;
if (mSingleScroll)
{
if (Math.abs(aMotionEvent.getY() - mStartY) > mMinDistanceMoved)
return super.dispatchTouchEvent(aMotionEvent);
}
else
return super.dispatchTouchEvent(aMotionEvent);
}
if (mSingleScroll)
{
if (mVelocity == null)
{
mVelocity = VelocityTracker.obtain();
mStartY = aMotionEvent.getY();
}
mVelocity.addMovement(aMotionEvent);
}
return super.dispatchTouchEvent(aMotionEvent);
}
}
所以代码简单如下。 （不要忘记将xml中的ListView更改为SingleScrollListView）不需要手势监听器。
listView = (SingleScrollListView) findViewById(R.id.list);
listView.setSingleScroll(true);
答案 1 :(得分：2)
您可以在onTouchListener（）中使用listView.setScrollY（int value）。您可以截取触摸事件并测量项目视图的高度，然后设置ScrollY（列表视图的当前高度+项目的高度）。