Android data storage (1) -- shared preferences

Sharedpreferences indicates "Sharing Preferences"

It is shared by all activities and cannot share preferences outside the application package. Preferences are stored as a set of "keys/values. The supported data types are as follows:

1. Boolean Value

2. floating point value

3. integer value

4. long integer value

5. String Value

It is used as follows:

1. Create a sharedpreferences object instance

2. Create a sharedpreferences. Editor to modify the preference content.

3. Submit changes

Note: If you want to support a specific activity, you must specify the preference for obtaining the private mode. In this way, the activity in the application cannot be accessed.

The following are different method call preferences:

1. Obtain the activity's private preferences

Preferences = getpreferences (Mode_private);

Code snippet 9.1.1 activity private preference acquisition

2. Get application preferences

Sharedpreferences = getsharedpreferences ("sharedpreferences ",
Mode_private);

Code snippet 9.1.2 get application preferences

Note: both private and public preferences have the file storage mode, which allows you to perform different jobs on created preferences files.

1. Context. mode_private (0)

The default mode indicates that the file is private data and can only be accessed by the application. In this mode, if a file is written, the original file content will be overwritten.

2. Context. mode_append (32768)
Append mode. This mode checks whether the file exists. If yes, append the content to the file instead of overwriting it.

3. Context. mode_world_readable (1)

Indicates that the current file can be read by other applications.

4. Context. mode_world_writeable (2)

Indicates that the current file can be written by other applications.

Sharedpreferences contains some methods through which the stored content can be easily obtained.

Method	Description
Sharedpreferences. Contains ()	Check whether the preference exists by name
Sharedpreferences. Edit ()	Get Editor, mainly used to store information
Sharedpreferences. getall ()	Obtain all key-value pairs
Sharedpreferences. getboolean ()	Obtains a preference with a Boolean value.
Sharedpreferences. getfloat ()	Gets a preference with a value of float.
Sharedpreferences. getint ()	Gets a preference with a value of Int.
Sharedpreferences. getlong ()	Gets a preference with a long value.
Sharedpreferences. getstring ()	Gets a preference with a value of string.

Table 9.1.1 sharedpreferences

 

 

Through the sharedpreferences. Edit () method, we can get the editor, and the editor method is as follows:

Method	Description
Sharedpreferences. Editor. Clear ()	Remove all preferences. Note: This operation can be performed and submitted only after any modification.
Sharedpreferences. Editor. Remove ()	Remove a preference by name. The priority of this operation is as follows:
Sharedpreferences. Editor. putboolean ()	Preference for storing values as Boolean
Sharedpreferences. Editor. putfloat ()	Preference for storing a value of float
Sharedpreferences. Editor. putint ()	Preference for storing an int Value
Sharedpreferences. Editor. putlong ()	Preference for long storage
Sharedpreferences. Editor. putstring ()	Preference for storing values as string
Sharedpreferences. Editor. Commit ()	Submit all changes to this edit session

Table 9.1.2 sharedpreferences. Editor Method

The following is an example:

Androidstudy_sharepreferences