我在ListView内嵌了LinearLayout FrameLayout。我能够在ObjectAnimation's内对其他视图执行LinearLayout，但在ListView上执行动画时会收到空指针错误。随附的是详细信息和错误日志：
有问题的ListView在附加的布局中：
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/frame"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<!-- CalendarView and ListView -->
<LinearLayout
android:id="@+id/layout_contents"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:animateLayoutChanges="true" >
<CalendarView
android:id="@+id/calendarView1"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="3"
android:background="@drawable/color_border"
/>
<RelativeLayout
android:id="@+id/button_relative"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="0.3"
android:background="#807FE817" >
<ImageButton
android:id="@+id/change_cols_btn"
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:background="@drawable/ic_btn_round_more_normal" />
</RelativeLayout>
<ListView
android:id="@+id/listview1"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="3" >
</ListView>
</LinearLayout>
<!-- Header consisting of Month and Day abbreviations -->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:background="#FFFFFFFF" >
<TextView
android:id="@+id/month_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="January"
android:textSize="20sp"
android:textStyle="bold"
android:paddingTop="10dp" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:paddingTop="10dp" >
<TextView
android:id="@+id/sunday_txt"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:gravity="center_horizontal"
android:text="S" />
<TextView
android:id="@+id/monday_txt"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:gravity="center_horizontal"
android:text="M" />
</LinearLayout>
</LinearLayout>
</FrameLayout>
ListView是在片段onCreateView
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.calendar_list, container, false);
final ListView listview = (ListView) view.findViewById(R.id.listview1);
String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
"Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
"Linux", "OS/2", "Ubuntu", "Windows7", "Max OS X", "Linux",
"OS/2", "Ubuntu", "Windows7", "Max OS X", "Linux", "OS/2",
"Android", "iPhone", "WindowsMobile" };
final ArrayList<String> list = new ArrayList<String>();
for (int i = 0; i < values.length; ++i) {
list.add(values[i]);
}
final StableArrayAdapter adapter = new StableArrayAdapter(getActivity(),
android.R.layout.simple_list_item_1, list);
listview.setAdapter(adapter);
动画在clickListener中运行，代码如下：
expand_btn = (ImageButton)view.findViewById(R.id.change_cols_btn);
expand_btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
int calendarHeight = calendarView1.getHeight();
final float translateBy = calendarHeight * 0.6f;
ObjectAnimator animator;
if (expanded) {
animator = ObjectAnimator.ofFloat(listView, "translationY", - translateBy);
animator.setDuration(300);
animator.start();
Logcat收到的错误是：
09-18 16:03:15.506: E/AndroidRuntime(24637): FATAL EXCEPTION: main
09-18 16:03:15.506: E/AndroidRuntime(24637): java.lang.NullPointerException
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.animation.PropertyValuesHolder.setupSetterAndGetter(PropertyValuesHolder.java:505)
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.animation.ObjectAnimator.initAnimation(ObjectAnimator.java:392)
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.animation.ValueAnimator.setCurrentPlayTime(ValueAnimator.java:502)
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.animation.ValueAnimator.start(ValueAnimator.java:913)
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.animation.ValueAnimator.start(ValueAnimator.java:923)
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.animation.ObjectAnimator.start(ObjectAnimator.java:370)
09-18 16:03:15.506: E/AndroidRuntime(24637): at com.example.eventsmockup.ShowEvents$3.onClick(ShowEvents.java:195)
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.view.View.performClick(View.java:4354)
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.view.View$PerformClick.run(View.java:17961)
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.os.Handler.handleCallback(Handler.java:725)
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.os.Handler.dispatchMessage(Handler.java:92)
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.os.Looper.loop(Looper.java:137)
09-18 16:03:15.506: E/AndroidRuntime(24637): at android.app.ActivityThread.main(ActivityThread.java:5328)
09-18 16:03:15.506: E/AndroidRuntime(24637): at java.lang.reflect.Method.invokeNative(Native Method)
09-18 16:03:15.506: E/AndroidRuntime(24637): at java.lang.reflect.Method.invoke(Method.java:511)
09-18 16:03:15.506: E/AndroidRuntime(24637): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
09-18 16:03:15.506: E/AndroidRuntime(24637): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
09-18 16:03:15.506: E/AndroidRuntime(24637): at dalvik.system.NativeStart.main(Native Method)
非常感谢您的协助！
答案 0 :(得分：-3)
这是由代码中的重复引起的。