It is very standard to save data to file and read data from file.

Closed stream: reader (read) writer (write)

 

Byte stream: inputstream (read data) outputstream (write data)

1. byte stream

Inputstream (read), outputstream (write)

2. Streams

Reader and writer)

 

Conclusion: as long as the plain text data is processed, the use of the byte stream should be given priority, in addition to the byte stream.

 

Write content to the file

Try {

Fileoutputstream Fos = openfileoutput (internal_filename, mode_append );

FOS. Write ("Michael \ n". getbytes ());

// The getbytes () method of string is used to convert string => byte []

FOS. Write ("89 \ n". getbytes ());

FOS. Close ();

Toast. maketext (this, "Write successful! ", Toast. length_long). Show ();

} Catch (exception e ){

E. printstacktrace ();

Show. settext ("Write failed! ");

}

 

The saved location of info.txt is data/package name/files/info.txt.

The data/package name/Files directory is used by default to read specific files, as shown below:

Try {

Fileinputstream FCM = openfileinput (internal_filename );

Bufferedreader BR = new bufferedreader (New inputstreamreader (FCM, "UTF-8"); // read Row Operations

String content = "";

String line;

While (line = Br. Readline ())! = NULL ){

Content + = line + "\ n ";

}

BR. Close ();

FCM. Close ();

Show. settext (content );

 

} Catch (exception e ){

E. printstacktrace ();

Toast. maketext (this, "failed to read data! ", Toast. length_long). Show ();

}

 

Write a user class as follows:

Public class user {

Private string name;

Private long date;

Private int count;

Public user (string name, long date, int count ){

Super ();

This. Name = Name;

This. Date = date;

This. Count = count;

}

Public user (string name, int count ){

Super ();

This. Name = Name;

This. Count = count;

This. Date = system. currenttimemillis ();

}

Public String getname (){

Return name;

}

Public void setname (string name ){

This. Name = Name;

}

Public long getdate (){

Return date;

}

Public void setdate (long date ){

This. Date = date;

}

Public int getcount (){

Return count;

}

Public void setcount (INT count ){

This. Count = count;

}

@ Override

Public String tostring (){

Return "User [name =" + name + ", date =" + date + ", Count =" + count

+ "]";

}

 

Public String writeinfo (){

Return name + "," + date + "," + count;

}

 

}

 

Click the Add User button once to add a piece of data to the file, as shown below:

Internalstoragetool. appendinfo (this, new user ("BB", 3 ));

The following method is added:

// Append user information

Public static Boolean appendinfo (context, user ){

Try {

Fileoutputstream Fos = context. openfileoutput (Const. in_filename, context. mode_append );

// The append permission is available here. Context. mode_append

FOS. Write (user. writeinfo () + "\ n"). getbytes ());

// Convert to byte write

FOS. Close ();

Return true;

} Catch (exception e ){

E. printstacktrace ();

Return false;

}

}

 

Click a button to read data from all users.

// Read all user information

Public static list <user> readallinfo (context ){

Try {

Fileinputstream FCM = context. openfileinput (Const. in_filename );

Bufferedreader BR = new bufferedreader (New inputstreamreader (FCM, "UTF-8 "));

List <user> Users = new arraylist <user> ();

String line;

While (line = Br. Readline ())! = NULL ){

Users. Add (PARSE (line ));

}

FCM. Close ();

BR. Close ();

Return users;

} Catch (exception e ){

E. printstacktrace ();

Return NULL;

}

}

 

The parse () method is as follows:

Private Static user parse (string info ){

String [] infoes = info. Split (",");

Long date = long. parselong (infoes [1]);

Int COUNT = integer. parseint (infoes [2]);

Return new user (infoes [0], date, count );

}