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我在這裏有一個奇怪的問題後返回null,我有一個對話片段和這個方法裏面:onPageScrolled方法改變爲最新的支持-V4庫
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
currentPosition = position;
currentPositionOffset = positionOffset;
scrollToChild(position, (int) (positionOffset *
tabsContainer.getChildAt(position).getWidth()));
invalidate();
if (delegatePageListener != null) {
delegatePageListener.onPageScrolled(position,
positionOffset, positionOffsetPixels);
}
}
當我使用支持 - 一箇舊版本v4.jar它工作正常,但是當我使用它的最新版本,這個方法:
scrollToChild(position, (int) (positionOffset *
tabsContainer.getChildAt(position).getWidth()));
返回此錯誤:
06-19 11:56:23.764: E/AndroidRuntime(1024): java.lang.NullPointerException
06-19 11:56:23.764: E/AndroidRuntime(1024): at
com.astuetz.PagerSlidingTabStrip$PageListener.onPageScrolled
(PagerSlidingTabStrip.java:361)
06-19 11:56:23.764: E/AndroidRuntime(1024): at
android.support.v4.view.ViewPager.onPageScrolled(ViewPager.java:1712)
06-19 11:56:23.764: E/AndroidRuntime(1024): at
android.support.v4.view.ViewPager.pageScrolled(ViewPager.java:1633)
06-19 11:56:23.764: E/AndroidRuntime(1024): at
android.support.v4.view.ViewPager.scrollToItem(ViewPager.java:581)
06-19 11:56:23.764: E/AndroidRuntime(1024): at
android.support.v4.view.ViewPager.onLayout(ViewPager.java:1600)
你明白什麼是錯的?
我的猜測是位置爲空,但我該怎麼做,爲什麼會發生這種情況! – user3694470