java - com.edmodo.rangebar.RangeBar 与 viewpager

Question

我正在尝试将库:co​​m.edmodo.rangebar.RangeBar 与 ViewPager 一起使用，但是当我尝试将它添加到 viewpager 时，它给出了一个空指针异常。但是当我在 ViewPager 之外使用它时没有问题。并且 fragment 不是选项，因为您不能将 fragment 嵌套在 fragment 中的 viewpager 中。

<android.support.v4.view.ViewPager
     android:layout_width="match_parent"
     android:layout_height="wrap_content">

     <LinearLayout
          android:id="@+id/ll_filter_seekbar"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:orientation="horizontal">


                <com.edmodo.rangebar.RangeBar
                    xmlns:custom="http://schemas.android.com/apk/res-auto"
                    android:id="@+id/rangebar"
                    android:layout_width="0dp"
                    android:layout_height="wrap_content"
                    android:layout_weight="1"
                    custom:tickCount="2000"
                    custom:tickHeight="0dp" />


      </LinearLayout>
</android.support.v4.view.ViewPager>

错误:

java.lang.NullPointerException
    at com.edmodo.rangebar.RangeBar.onDraw(RangeBar.java:265)
    at android.view.View.draw(View.java:14465)
    at android.view.View.draw(View.java:14350)
    at android.view.ViewGroup.drawChild(ViewGroup.java:3103)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2940)
    at android.view.View.draw(View.java:14348)
    at android.view.ViewGroup.drawChild(ViewGroup.java:3103)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2940)
    at android.view.View.draw(View.java:14468)
    at android.support.v4.view.ViewPager.draw(ViewPager.java:2171)
    at android.view.View.draw(View.java:14350)
    at android.view.ViewGroup.drawChild(ViewGroup.java:3103)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2940)
    at android.view.View.draw(View.java:14348)
    at android.view.ViewGroup.drawChild(ViewGroup.java:3103)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2940)
    at android.view.View.draw(View.java:14468)
    at android.widget.FrameLayout.draw(FrameLayout.java:472)
    at android.widget.ScrollView.draw(ScrollView.java:1603)
    at android.view.View.draw(View.java:14350)
    at android.view.ViewGroup.drawChild(ViewGroup.java:3103)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2940)
    at android.view.View.draw(View.java:14468)
    at android.widget.FrameLayout.draw(FrameLayout.java:472)
    at com.android.layoutlib.bridge.impl.RenderSessionImpl.render(RenderSessionImpl.java:584)
    at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:338)
    at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:332)
    at com.android.tools.idea.rendering.RenderService$3.compute(RenderService.java:560)
    at com.android.tools.idea.rendering.RenderService$3.compute(RenderService.java:549)
    at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:932)
    at com.android.tools.idea.rendering.RenderService.createRenderSession(RenderService.java:549)
    at com.android.tools.idea.rendering.RenderService.render(RenderService.java:622)
    at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.doRender(AndroidLayoutPreviewToolWindowManager.java:585)
    at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.access$1900(AndroidLayoutPreviewToolWindowManager.java:80)
    at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$6$1.run(AndroidLayoutPreviewToolWindowManager.java:527)
    at com.intellij.openapi.progress.impl.ProgressManagerImpl$2.run(ProgressManagerImpl.java:178)
    at com.intellij.openapi.progress.ProgressManager.executeProcessUnderProgress(ProgressManager.java:209)
    at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:212)
    at com.intellij.openapi.progress.impl.ProgressManagerImpl.runProcess(ProgressManagerImpl.java:171)
    at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$6.run(AndroidLayoutPreviewToolWindowManager.java:522)
    at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:320)
    at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:310)
    at com.intellij.util.ui.update.MergingUpdateQueue$2.run(MergingUpdateQueue.java:254)
    at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:269)
    at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:227)
    at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:217)
    at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:238)
    at com.intellij.util.Alarm$Request$1.run(Alarm.java:327)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)

PageAdapter 的代码:

public class FilterPagerAdapter extends PagerAdapter {

private static final int NUM_PAGES = 1;

@Override
public int getCount() {
    return NUM_PAGES;
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
    int resId = 0;
    Tools.LOG_DEBUG("This page: " + position);
    switch (position) {
        case 0:
            resId = R.id.page_one;
            break;
    }
    return container.findViewById(resId);
}

@Override
public boolean isViewFromObject(View arg0, Object arg1) {
    return arg0 == ((View) arg1);
}
}

Answer 1

ViewPager 通过它的适配器添加它的 subview (页面)，你不应该像你那样直接在 xml 布局中添加 subview 。因此，只保留 ViewPager 的初始布局:

<android.support.v4.view.ViewPager
     android:layout_width="match_parent"
     android:layout_height="wrap_content" />

使用页面内容创建一个新的 xml 布局(如 page.xml):

<LinearLayout
      android:id="@+id/ll_filter_seekbar"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:orientation="horizontal">


            <com.edmodo.rangebar.RangeBar
                xmlns:custom="http://schemas.android.com/apk/res-auto"
                android:id="@+id/rangebar"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                custom:tickCount="2000"
                custom:tickHeight="0dp" />


</LinearLayout>

并通过获取对 LayoutInflater 的引用(将其直接传递给适配器或从 Context 创建它)然后使用它，将其连接到适配器中根据您的位置膨胀上面的 page.xml 布局。