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34understanding of the Android virtual machine, including the memory management mechanism garbage collection mechanism. Virtual machine is small, space is very small, talk about the size of the mobile device virtual machine limit 16M, talk about loading pictures of how to deal with large images, compression. Garbage collection, no reference objects, at some point will be the system GC off, like Java. 35. How the framework works and how activity generates a view, and what the mechanism is. Reflection+configuration file to do. Can talk about the activity of the source code, for example, each activity has window.callback and Keyevent.callback, some callback interface or function bar. When the framework creates the activity, it invokes the callback methods inside, invoking the activity lifecycle-related methods. Activity creates a view that is drawn through OnDraw, and before this view is drawn, the Onmeasure method is called to calculate the size of the display.36. Some limitations of Android itself, such as the APK packet size limit, the time limit when reading large files. This question asked questions, APK packet size limit is not good to say, need for speed 100M or can be installed on the mobile phone, the world Google Market Big program main program is very small5~10M download Sdcard15 minutes to request a refund APK package, thin package, footage stored on the server. Game program. The time limit for reading large files should be the time limit within the main thread. Activity should not exceed 5 seconds. Service not to exceed 20 seconds37How to load the music information and how to improve its efficiency. Android provides Mediascanner,mediastore interface, music file information will be stored in the System database table, can be obtained through content provider, display, improve efficiency, is a common problem, can be answered from the following aspects, Load data in batches, delay load data, reasonably use cache, etc. ..38. How does the ListView improve its efficiency? Multiplexing Convertview, historical view objects reduce the number of child queries Viewholder asynchronously load data, page load data, drop-down load. Use a static view object to avoid creating too many view.39. After you start the app, change the system language and the language of the app will change? 40. Start a program, you can click on the main interface icon to enter, you can also jump from a program in the past, what is the difference between the two? No difference, through the icon is launcher to start, jump is another application started. The difference is based on the configuration of the activity within the manifest, the activity may be placed in different task stacks intent flag Flag_new_task41.  What is the difference between an Android program and a Java program? Android app developed with Android SDK, Java program developed with JAVASDK.  The Android SDK references most Java SDKs, and a few are discarded by the Android SDK, such as the interface section, java.awt swing In addition to Java.awt.font, the package is discarded and cannot be used in Android platform development. Android SDK Add tool jar HttpClient, pull OpenGL porting Java games or J2ME programs to the Android platform, the difference between the Android SDK and the Java SDK is a great place to note. Sampledataadpter ()

android151 Notes 3