java-如何动态更改导航抽屉的标题布局背景颜色?
作者:互联网
如您所知,android studio具有一个Navigation Drawer Activity,它可以在layout文件夹内自行创建一堆布局.
nav_header_main.xml是包含NavigationView标头组件的布局.我已经在上图中突出显示了它,并且具有以下代码:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/sideNavLayout"
android:layout_width="match_parent"
android:layout_height="@dimen/nav_header_height"
android:background="@drawable/side_nav_bar"
android:gravity="bottom"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:theme="@style/ThemeOverlay.AppCompat.Dark">
<ImageView
android:id="@+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingTop="@dimen/nav_header_vertical_spacing"
android:src="@android:drawable/sym_def_app_icon" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingTop="@dimen/nav_header_vertical_spacing"
android:text="Android Studio"
android:textAppearance="@style/TextAppearance.AppCompat.Body1" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="android.studio@android.com" />
</LinearLayout>
我想从MainActivity.java更改上图中的突出显示部分的背景,如下所示:
LinearLayout sideNavLayout;
sideNavLayout = (LinearLayout) findViewById(R.id.sideNavLayout);
sideNavLayout.setBackgroundResource(R.drawable.my_side_nav_bar);
但是,无论我在哪里使用它,我都会收到错误消息:
java.lang.NullPointerException
有人可以在这方面帮助我吗?
解决方法:
您应该给navview标头布局充气以访问子级
NavigationView navView= (NavigationView) findViewById(R.id.nav_view);
View header=navView.getHeaderView(0);
LinearLayout sideNavLayout = (LinearLayout)header.findViewById(R.id.sideNavLayout);
sideNavLayout.setBackgroundResource(R.drawable.my_side_nav_bar);
标签:android-layout,layout,navigation-drawer,java,android 来源: https://codeday.me/bug/20191026/1937801.html