Memory management
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This document discusses data storage options for Android applications, including shared preferences and internal storage. Shared preferences allow storing primitive data like strings and integers that persist across sessions, while internal storage can be used to privately save files on the device. The document outlines how to read and write to both shared preferences and internal storage files in Android.
Memory management
- 1. Android By : Vikash Patel Vicky_1886@yahoo.com +91 - 9429350401
- 2. Content • 1. Data Storage ? – 1.1. Shared Preferences – 1.2. Internal Storage
- 3. Shared Preferences • The SharedPreferences class provides a general framework that allows you to save and retrieve persistent key-value pairs of primitive data types. • You can use SharedPreferences to save any primitive data: booleans, floats, ints, longs, and strings. This data will persist across user sessions (even if your application is killed). • To get a Shared Preferences object for your application, use one of two methods: Back …
- 4. Continue … • getSharedPreferences() - Use this if you need multiple preferences files identified by name, which you specify with the first parameter. • getPreferences() - Use this if you need only one preferences file for your Activity. • Because this will be the only preferences file for your Activity, you don't supply a name. Back …
- 5. Continue … • To write values: • Call edit() to get a SharedPreferences.Editor. • Add values with methods such as putBoolean() and putString(). • Commit the new values with commit() • To read values, use SharedPreferences methods such as getBoolean() and getString(). Back …
- 7. Internal Storage • You can save files directly on the device's internal storage. By default, files saved to the internal storage are private to your application and other applications cannot access them (nor can the user). When the user uninstalls your application, these files are removed. • To create and write a private file to the internal storage: • Call openFileOutput() with the name of the file and the operating mode. This returns a FileOutputStream. • Write to the file with write(). • Close the stream with close(). Back …
- 9. Continue … • MODE_PRIVATE will create the file (or replace a file of the same name) and make it private to your application. Other modes available are: MODE_APPEND, MODE_WORLD_READABLE, and MODE_WORLD_WRITEABLE. • To read a file from internal storage: • Call openFileInput() and pass it the name of the file to read. This returns a FileInputStream. • Read bytes from the file with read(). • Then close the stream with close(). Back …
- 10. Continue … • Saving cache files – If you'd like to cache some data, rather than store it persistently, you should use getCacheDir() to open a File that represents the internal directory where your application should save temporary cache files. – When the device is low on internal storage space, Android may delete these cache files to recover space. However, you should not rely on the system to clean up these files for you. – You should always maintain the cache files yourself and stay within a reasonable limit of space consumed, such as 1MB. When the user uninstalls your application, these files are removed. Back …