Dialg - ImageView - NullPointerException - setOnClickListener

Question

我有一个NullpointerException，但我无法弄清楚原因！请帮助我，因为我正在努力解决这个问题：

这是我的XML资源：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#FFFFFF" >

<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_margin="20dp"
    android:orientation="horizontal" >

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="3dp"
        android:gravity="right"
        android:orientation="vertical" >

        <TextView
            android:id="@+id/txt_speciality_type"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Name: " />

        <TextView
            android:id="@+id/textView4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="add:" />

        <TextView
            android:id="@+id/textView5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="phone :" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="3dp"
        android:orientation="vertical" >

        <TextView
            android:id="@+id/textView3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="abc abc abc" />

        <TextView
            android:id="@+id/textView44"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="abc" />

        <TextView
            android:id="@+id/textView55"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="230020202" />
    </LinearLayout>
</LinearLayout>

<ImageView
    android:id="@+id/imageViewClose"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
    android:src="@drawable/close_selector" />
 </RelativeLayout>

在我的Java说明之下： setContentView在使用实际TextView

之前

final Dialog dialog = new Dialog(searchActivity.this);
dialog.setContentView(R.layout.custom_dialog);``
ImageView closeBtn =(ImageView)findViewById(R.id.imageViewClose);
closeBtn.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View arg0) {
                    finish();
                }
            });

Logcat错误：

java.lang.NullPointerException
        at com.itraan.Test.searchActivity$2.onItemClick(searchActivity.java:902)
        at android.widget.AdapterView.performItemClick(AdapterView.java:308)
        at android.widget.AbsListView.performItemClick(AbsListView.java:1483)
        at android.widget.AbsListView$PerformClick.run(AbsListView.java:3485)
        at android.widget.AbsListView$3.run(AbsListView.java:4843)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:157)
        at android.app.ActivityThread.main(ActivityThread.java:5356)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
        at dalvik.system.NativeStart.main(Native Method)

提前谢谢。