我试图用ViewPager使用PullToRefresh GridView,这会导致ClassCastException的崩溃.这是例外.
FATAL EXCEPTION: main java.lang.classCastException: android.support.v4.view.ViewPager$LayoutParams at android.widget.LinearLayout.measureVertical(LinearLayout.java:360) at android.widget.LinearLayout.onMeasure(LinearLayout.java:309) at android.view.View.measure(View.java:8313) at android.widget.RelativeLayout.measureChild(RelativeLayout.java:566) at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:381) at android.view.View.measure(View.java:8313) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) at android.view.View.measure(View.java:8313) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) at android.view.View.measure(View.java:8313) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) at android.view.View.measure(View.java:8313) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) at android.view.View.measure(View.java:8313) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) at android.view.View.measure(View.java:8313) at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:581) at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:365) at android.view.View.measure(View.java:8313) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) at android.view.View.measure(View.java:8313) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1017) at android.widget.LinearLayout.measureVertical(LinearLayout.java:386) at android.widget.LinearLayout.onMeasure(LinearLayout.java:309) at android.view.View.measure(View.java:8313) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) at android.view.View.measure(View.java:8313) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) at android.view.View.measure(View.java:8313) at android.view.ViewRoot.performTraversals(ViewRoot.java:845) at android.view.ViewRoot.handleMessage(ViewRoot.java:1865) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:130) at android.app.ActivityThread.main(ActivityThread.java:3687) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:507) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) at dalvik.system.NativeStart.main(Native Method)
这是它被实现的代码段.
PULL_TO_REFRESH = (PullToRefreshGridView)findViewById(R.id.groupList);
mGroupList = PULL_TO_REFRESH.getAdapterView();
Vector<View> pages = new Vector<View>();
pages.add(mGroupList);
ViewPager vp = (ViewPager)findViewById(R.id.myfivepanelpager);
CustomPagerAdapter adapter = new CustomPagerAdapter(this,pages);
vp.setAdapter(adapter);
// Set a listener to be invoked when the list should be refreshed.
PULL_TO_REFRESH.setonRefreshListener(new OnRefreshListener() {
@Override
public void onRefresh() {
// Todo Auto-generated method stub
}
});
这是来自PullToRefresh库的代码片段,可能是原因.
package com.syncusup.pulltorefresh.library.my; import android.content.Context; import android.os.Handler; import android.util.AttributeSet; import android.view.LayoutInflater; import android.view.MotionEvent; import android.view.View; import android.view.View.OnTouchListener; import android.view.ViewGroup; import android.view.animation.AccelerateDecelerateInterpolator; import android.view.animation.Animation; import android.view.animation.Interpolator; import android.view.animation.LinearInterpolator; import android.view.animation.RotateAnimation; import android.widget.AdapterView; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.listadapter; import android.widget.ProgressBar; import android.widget.TextView; import com.syncusup.R; public abstract class PullToRefreshBase<T extends AdapterView<listadapter>> extends LinearLayout implements OnTouchListener { private final class SmoothScrollRunnable implements Runnable { static final int ANIMATION_DURATION_MS = 190; static final int ANIMATION_FPS = 1000 / 60; private final Interpolator interpolator; private final int scrollToY; private final int scrollFromY; private final Handler handler; private boolean continueRunning = true; private long startTime = -1; private int currentY = -1; public SmoothScrollRunnable(Handler handler,int fromY,int toY) { this.handler = handler; this.scrollFromY = fromY; this.scrollToY = toY; this.interpolator = new AccelerateDecelerateInterpolator(); } @Override public void run() { /** * Only set startTime if this is the first time we're starting,else * actually calculate the Y delta */ if (startTime == -1) { startTime = System.currentTimeMillis(); } else { /** * We do do all calculations in long to reduce software float * calculations. We use 1000 as it gives us good accuracy and * small rounding errors */ long normalizedTime = (1000 * (System.currentTimeMillis() - startTime)) / ANIMATION_DURATION_MS; normalizedTime = Math.max(Math.min(normalizedTime,1000),0); final int deltaY = Math.round((scrollFromY - scrollToY) * interpolator.getInterpolation(normalizedTime / 1000f)); this.currentY = scrollFromY - deltaY; setHeaderScroll(currentY); } // If we're not at the target Y,keep going... if (continueRunning && scrollToY != currentY) { handler.postDelayed(this,ANIMATION_FPS); } } public void stop() { this.continueRunning = false; this.handler.removeCallbacks(this); } }; // =========================================================== // Constants // =========================================================== static final int PULL_TO_REFRESH = 0; static final int RELEASE_TO_REFRESH = PULL_TO_REFRESH + 1; static final int REFRESHING = RELEASE_TO_REFRESH + 1; static final int EVENT_COUNT = 3; // =========================================================== // Fields // =========================================================== private int state = PULL_TO_REFRESH; private T adapterView; private boolean isPullToRefreshEnabled = true; private ProgressBar headerProgress; private TextView headerText; private ImageView headerImage; private Animation flipAnimation,reverseAnimation; private int headerHeight; private final Handler handler = new Handler(); private OnTouchListener onTouchListener; private OnRefreshListener onRefreshListener; private SmoothScrollRunnable currentSmoothScrollRunnable; private float startY = -1; private final float[] lastYs = new float[EVENT_COUNT]; private String releaseLabel; private String pullLabel; private String refreshingLabel; // =========================================================== // Constructors // =========================================================== public PullToRefreshBase(Context context) { this(context,null); } public PullToRefreshBase(Context context,AttributeSet attrs) { super(context,attrs); init(context,attrs); } // =========================================================== // Getter & Setter // =========================================================== /** * Get the Wrapped AdapterView. Anything returned here has already been * added to the content view. * * @return The AdapterView which is currently wrapped */ public final T getAdapterView() { return adapterView; } /** * Whether Pull-to-Refresh is enabled * * @return enabled */ public boolean isPullToRefreshEnabled() { return isPullToRefreshEnabled; } /** * Mark the current Refresh as complete. Will Reset the UI and hide the * Refreshing View */ public void onRefreshComplete() { resetHeader(); } public void setonRefreshListener(OnRefreshListener listener) { onRefreshListener = listener; } /** * A mutator to enable/disable Pull-to-Refresh for the current AdapterView * * @param enable * Whether Pull-To-Refresh should be used */ public void setPullToRefreshEnabled(boolean enabled) { this.isPullToRefreshEnabled = enabled; } public void setReleaseLabel(String releaseLabel) { this.releaseLabel = releaseLabel; } public void setPullLabel(String pullLabel) { this.pullLabel = pullLabel; } public void setRefreshingLabel(String refreshingLabel) { this.refreshingLabel = refreshingLabel; } public void setHeaderProgress(ProgressBar headerProgress) { this.headerProgress = headerProgress; } // =========================================================== // Methods for/from SuperClass/Interfaces // =========================================================== @Override public void setonTouchListener(OnTouchListener listener) { onTouchListener = listener; } @Override public boolean onTouch(View view,MotionEvent ev) { if (isPullToRefreshEnabled) { // Returning true here stops the ListView being scrollable while we // refresh if (state == REFRESHING) { return true; } else { return onAdapterViewTouch(view,ev); } } return false; } /** * This is implemented by derived classes to return the created AdapterView. * If you need to use a custom AdapterView (such as a custom ListView),* override this method and return an instance of your custom class. * * Be sure to set the ID of the view in this method,especially if you're * using a ListActivity or ListFragment. * * @param context * @param attrs * AttributeSet from wrapped class. Means that anything you * include in the XML layout declaration will be routed to the * AdapterView * @return New instance of the AdapterView */ protected abstract T createAdapterView(Context context,AttributeSet attrs); // =========================================================== // Methods // =========================================================== protected final void resetHeader() { state = PULL_TO_REFRESH; initializeYsHistory(); startY = -1; headerImage.setVisibility(View.VISIBLE); headerProgress.setVisibility(View.GONE); smoothScrollTo(0); } private void init(Context context,AttributeSet attrs) { setorientation(LinearLayout.VERTICAL); // Header ViewGroup header = (ViewGroup) LayoutInflater.from(context).inflate(R.layout.pull_to_refresh_header,this,false); headerText = (TextView) header.findViewById(R.id.pull_to_refresh_text); pullLabel = context.getString(R.string.pull_to_refresh_pull_label); refreshingLabel = context.getString(R.string.pull_to_refresh_refreshing_label); releaseLabel = context.getString(R.string.pull_to_refresh_release_label); headerImage = (ImageView) header.findViewById(R.id.pull_to_refresh_image); headerProgress = (ProgressBar) header.findViewById(R.id.pull_to_refresh_progress); addView(header,ViewGroup.LayoutParams.FILL_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT); measureView(header); headerHeight = header.getMeasuredHeight(); // AdapterView // By passing the attrs,we can add ListView/GridView params via XML adapterView = this.createAdapterView(context,attrs); adapterView.setonTouchListener(this); addView(adapterView,ViewGroup.LayoutParams.FILL_PARENT); // Animations flipAnimation = new RotateAnimation(0,-180,Animation.RELATIVE_TO_SELF,0.5f,0.5f); flipAnimation.setInterpolator(new LinearInterpolator()); flipAnimation.setDuration(250); flipAnimation.setFillAfter(true); reverseAnimation = new RotateAnimation(-180,0.5f); reverseAnimation.setInterpolator(new LinearInterpolator()); reverseAnimation.setDuration(250); reverseAnimation.setFillAfter(true); // Hide Header View setPadding(getPaddingLeft(),-headerHeight,getPaddingRight(),getPaddingBottom()); } private void measureView(View child) { ViewGroup.LayoutParams p = child.getLayoutParams(); if (p == null) { p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT); } int childWidthSpec = ViewGroup.getChildMeasureSpec(0,0 + 0,p.width); int lpHeight = p.height; int childHeightSpec; if (lpHeight > 0) { childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight,MeasureSpec.EXACTLY); } else { childHeightSpec = MeasureSpec.makeMeasureSpec(0,MeasureSpec.UNSPECIFIED); } child.measure(childWidthSpec,childHeightSpec); } private boolean onAdapterViewTouch(View view,MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_MOVE: updateEventStates(event); if (isPullingDownToRefresh() && startY == -1) { if (startY == -1) { startY = event.getY(); } return false; } if (startY != -1 && !adapterView.ispressed()) { pullDown(event,startY); return true; } break; case MotionEvent.ACTION_UP: initializeYsHistory(); startY = -1; if (state == RELEASE_TO_REFRESH) { setRefreshing(); if (onRefreshListener != null) { onRefreshListener.onRefresh(); } } else { smoothScrollTo(0); } break; } if (null != onTouchListener) { return onTouchListener.onTouch(view,event); } return false; } private void pullDown(MotionEvent event,float firstY) { float averageY = average(lastYs); int height = (int) (Math.max(averageY - firstY,0)); setHeaderScroll(height); if (state == PULL_TO_REFRESH && headerHeight < height) { state = RELEASE_TO_REFRESH; headerText.setText(releaseLabel); headerImage.clearanimation(); headerImage.startAnimation(flipAnimation); } if (state == RELEASE_TO_REFRESH && headerHeight >= height) { state = PULL_TO_REFRESH; headerText.setText(pullLabel); headerImage.clearanimation(); headerImage.startAnimation(reverseAnimation); } } private void setHeaderScroll(int y) { scrollTo(0,-y); } private int getHeaderScroll() { return -getScrollY(); } private void setRefreshing() { state = REFRESHING; headerText.setText(refreshingLabel); headerImage.clearanimation(); headerImage.setVisibility(View.INVISIBLE); headerProgress.setVisibility(View.VISIBLE); smoothScrollTo(headerHeight); } private float average(float[] ysArray) { float avg = 0; for (int i = 0; i < EVENT_COUNT; i++) { avg += ysArray[i]; } return avg / EVENT_COUNT; } private void initializeYsHistory() { for (int i = 0; i < EVENT_COUNT; i++) { lastYs[i] = 0; } } private void updateEventStates(MotionEvent event) { for (int i = 0; i < EVENT_COUNT - 1; i++) { lastYs[i] = lastYs[i + 1]; } float y = event.getY(); int top = adapterView.getTop(); lastYs[EVENT_COUNT - 1] = y + top; } private boolean isPullingDownToRefresh() { return isPullToRefreshEnabled && state != REFRESHING && isUserDraggingDownwards() && isFirstVisible(); } private boolean isFirstVisible() { if (this.adapterView.getCount() == 0) { return true; } else if (adapterView.getFirstVisiblePosition() == 0) { return adapterView.getChildAt(0).getTop() >= adapterView.getTop(); } else { return false; } } private boolean isUserDraggingDownwards() { return this.isUserDraggingDownwards(0,EVENT_COUNT - 1); } private boolean isUserDraggingDownwards(int from,int to) { return lastYs[from] != 0 && lastYs[to] != 0 && Math.abs(lastYs[from] - lastYs[to]) > 10 && lastYs[from] < lastYs[to]; } private void smoothScrollTo(int y) { if (null != currentSmoothScrollRunnable) { currentSmoothScrollRunnable.stop(); } this.currentSmoothScrollRunnable = new SmoothScrollRunnable(handler,getHeaderScroll(),y); handler.post(currentSmoothScrollRunnable); } // =========================================================== // Inner and Anonymous Classes // =========================================================== public static interface OnRefreshListener { public void onRefresh(); } }
解决方法
为了获得更好的答案,我必须看到您的CustomPagerAdapter的实现.
但是,由于CustomPagerAdapter的构造函数将一个数组/集合/向量的视图作为参数,假设CustomPagerAdapter的instantiateItem方法(或者如果您的CustomPagerAdapter是FragmentPagerAdapter的getItem方法)使用这些视图构建ViewPager的页面是否正确？
如果是这样,那可能是你的问题.
矢量<视图>页面变量包含已经是布局的一部分的视图.在这种情况下,(唯一)View中有mGroupList. mGroupList已经是布局的一部分.你不能做一个视图(在这种情况下是mGroupList)是两个不同父母的孩子.
而不是“找到”mGroupList,而是在CustomPagerAdapter的instantiateItem方法中创建一个全新的PullToRefreshGridView(通过代码或通过扩充相应的layout-xml).全新的PullToRefreshGridView实例将不再具有父权限,但是当ViewPager认为有必要时,它将成为ViewPager的子代.
为了使事情变得更简单,我建议使用FragmentPagerAdapter或FragmentStatePagerAdapter,它将在其getItem方法中返回一个适当的Fragment.然后,Fragment将在其onCreateView方法中返回正确的视图,其中包含您想要的PullToRefreshGridView.
https://developer.android.com/reference/android/support/v13/app/FragmentPagerAdapter.html
