access view components inside navigation view android

Question

i'm new in android programming, i had a problem for accessing view components inside navigation view. this is my code:

`

 <android.support.design.widget.NavigationView  android:id="@+id/nav_view"
    android:layout_width="100dp" android:layout_height="match_parent"
    android:layout_gravity="start" android:fitsSystemWindows="true">

    <RelativeLayout
        android:id="@+id/lay"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="60dp"
        android:background="#e4e4e4">

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/imageView3"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:src="@drawable/icon" />

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/imageView4"
            android:src="@drawable/icon2"
            android:layout_below="@+id/imageView3"
            android:layout_centerHorizontal="true" />

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/imageView5"
            android:src="@drawable/icon3"
            android:layout_below="@+id/imageView4"
            android:layout_centerHorizontal="true" />
    </RelativeLayout>
</android.support.design.widget.NavigationView>`

i just want to access imageview inside navigationview. i've search in google and i got no solution on it. help me to fix it.

ImageView item1 = (ImageView)findViewById(R.id.imageView3);
        item1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(getApplicationContext(), "just try", Toast.LENGTH_LONG).show();
            }
        });