包含布局的根视图上的NullPointerException

Question

美好的一天,我在尝试访问包含布局的RelativeLayout视图组时遇到NullPointerexception.在下面的代码中,它被命名为rootlayout.我有这个

date_layout.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

        android:id="@+id/my_layoutroot_id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#eeeeee"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin">

            <TextView
                android:id="@+id/date_from1_id"
                style="@style/date_text"
                android:layout_alignParentTop="true"
                android:text="@string/date_from1" />

            <TextView
                android:id="@+id/date_from2_id"
                style="@style/date_text"
                android:layout_alignBaseline="@+id/date_from1_id"
                android:layout_alignBottom="@+id/date_from1_id"
                android:layout_alignParentRight="true"
                android:text="@string/date_To1" />
               <TextView
    </RelativeLayout>

并在main_layout.xml中:

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <include layout="@layout/date_layout" android:id="@+id/datelayout_id"></include>"


<FrameLayout
    android:id="@+id/frame_id"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
</FrameLayout>

</LinearLayout>   

我的代码是:

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_layout);

        View view = findViewById(R.id.datelayout_id);
          rootlayout = (RelativeLayout)view.findViewById(R.id.my_layoutroot_id);
          rootlayout.setOnclickListener(this);   // am getting the NullPointerException here

任何想法我可能做错了什么？非常感谢!

Answer 1

您正在main_layout.xml中分配新的ID:

    <include layout="@layout/date_layout" android:id="@+id/datelayout_id">

rootlayout = (RelativeLayout)view.findViewById(R.id.datelayout_id); 应该修复NPE.