怎么在Android应用中实现一个查看内存使用情况功能

<&#63;xml version="1.0" encoding="utf-8"&#63;><manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.itheima28.memorydemo" android:versionCode="1" android:versionName="1.0" >  <uses-sdk  android:minSdkVersion="8"  android:targetSdkVersion="19" />     <application  android:allowBackup="true"  android:icon="@drawable/ic_launcher"  android:label="@string/app_name"  android:theme="@style/AppTheme" >  <activity   android:name="com.itheima28.memorydemo.MainActivity"   android:label="@string/app_name" >   <intent-filter>    <action android:name="android.intent.action.MAIN" />     <category android:name="android.intent.category.LAUNCHER" />   </intent-filter>  </activity> </application> </manifest>