在http://blog.csdn.net/yancychas/article/details/77254708這個的activity_main.xml基礎上，設定小紅點。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.administrator.materialtest.Main4Activity">

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="45dp">
        <TextView
            android:id="@+id/text_fragment"
            android:layout_gravity="center"
            android:gravity="center"
            android:text="TEXT"
            android:textSize="20sp"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </LinearLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/view_paper"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/>
    
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="55dp"
        android:background="@color/black"
        android:orientation="horizontal">

        <LinearLayout
            android:id="@+id/ll_chat"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:orientation="vertical">

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent">
                <LinearLayout
                    android:layout_centerInParent="true"
                    android:layout_width="match_parent"
                    android:orientation="vertical"
                    android:layout_height="match_parent">
                <ImageView
                    android:id="@+id/iv_chat"
                    android:layout_width="match_parent"
                    android:layout_height="0dp"
                    android:layout_weight="2"
                    android:paddingBottom="4dp"
                    android:src="@drawable/first" />

                <TextView
                    android:id="@+id/tv_chat"
                    android:layout_width="match_parent"
                    android:layout_height="0dp"
                    android:layout_weight="1"
                    android:gravity="center"
                    android:text="CHAT"
                    android:textColor="@drawable/second" />
                </LinearLayout>
                <TextView
                    android:id="@+id/number"
                    android:paddingTop="4dp"
                    android:layout_marginRight="25dp"
                    android:layout_alignParentTop="true"
                    android:layout_width="20dp"
                    android:layout_height="28dp"
                    android:background="@drawable/redcircle"
                    android:text="99"
                    android:gravity="center_horizontal"
                    android:textColor="@color/white"
                    android:visibility="visible"
                    android:layout_alignParentEnd="true" />
            </RelativeLayout>
        </LinearLayout>
 

        <LinearLayout
            android:id="@+id/ll_friends"
            android:orientation="vertical"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1">
            <ImageView
                android:id="@+id/iv_friends"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:src="@drawable/ic_backup"/>
            <TextView
                android:id="@+id/tv_friends"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:gravity="center"
                android:text="CHAT"
                android:textColor="@drawable/second"/>
        </LinearLayout>
 

        <LinearLayout
            android:id="@+id/ll_contacts"
            android:orientation="vertical"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1">
            <ImageView
                android:id="@+id/iv_contacts"
                android:layout_marginTop="3dp"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:src="@drawable/ic_comment"/>
            <TextView
                android:id="@+id/tv_contacts"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:gravity="center"
                android:text="CHAT"
                android:textColor="@drawable/second"/>
        </LinearLayout>
        <LinearLayout
            android:id="@+id/ll_settings"
            android:orientation="vertical"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1">
            <ImageView
                android:id="@+id/iv_settings"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:src="@drawable/ic_done"/>
            <TextView
                android:id="@+id/tv_settings"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:gravity="center"
                android:text="CHAT"
                android:textColor="@drawable/second"/>
        </LinearLayout>
        
    </LinearLayout>

</LinearLayout>