To save data into file in an android application, you have to follow the steps given bellow.
1. Create an object of the FileOutputStream class using the openFileOutput method.
Example :
FileOutputStream fou = openFileOutput("text.txt", MODE_WORLD_READABLE);
Here text.txt is the name of the file. You can use any of the file opening mode
a. MODE_PRIVATE : File is accessible by only the application that create it.
b. MODE_APPEND : Appending an existing file.
c. MODE_WORLD_WRITABLE : Allow write permission to all the applications.
2. Get an object of the OutPutStreamWriter class using the FileOutputStream object.
Example:
OutputStreamWriter osw = new OutputStreamWriter(fou);
3. Write the data using the write() method.
Example:
osw.write(Message);
4. For reading the data from the file, first you need to create an object of the FileInputStream class.
Example:
FileInputStream fis = openFileInput("text.txt");
5. Get an object of the InputStreamReader class .
Example:
InputStreamReader isr = new InputStreamReader(fis);
6. Finally read the data from the file as separate block of data having fixed size.
1. Create an object of the FileOutputStream class using the openFileOutput method.
Example :
FileOutputStream fou = openFileOutput("text.txt", MODE_WORLD_READABLE);
Here text.txt is the name of the file. You can use any of the file opening mode
a. MODE_PRIVATE : File is accessible by only the application that create it.
b. MODE_APPEND : Appending an existing file.
c. MODE_WORLD_WRITABLE : Allow write permission to all the applications.
2. Get an object of the OutPutStreamWriter class using the FileOutputStream object.
Example:
OutputStreamWriter osw = new OutputStreamWriter(fou);
3. Write the data using the write() method.
Example:
osw.write(Message);
4. For reading the data from the file, first you need to create an object of the FileInputStream class.
Example:
FileInputStream fis = openFileInput("text.txt");
5. Get an object of the InputStreamReader class .
Example:
InputStreamReader isr = new InputStreamReader(fis);
6. Finally read the data from the file as separate block of data having fixed size.
activity_main.xml
1: <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
2: xmlns:tools="http://schemas.android.com/tools"
3: android:layout_width="match_parent"
4: android:layout_height="match_parent"
5: android:paddingBottom="@dimen/activity_vertical_margin"
6: android:paddingLeft="@dimen/activity_horizontal_margin"
7: android:paddingRight="@dimen/activity_horizontal_margin"
8: android:paddingTop="@dimen/activity_vertical_margin"
9: tools:context=".MainActivity" >
10: <EditText
11: android:id="@+id/msg"
12: android:layout_width="wrap_content"
13: android:layout_height="wrap_content"
14: android:layout_alignParentTop="true"
15: android:layout_centerHorizontal="true"
16: android:layout_marginTop="20dp"
17: android:ems="10"
18: android:hint="Enter a message"
19: >
20: <requestFocus />
21: </EditText>
22: <Button
23: android:id="@+id/LOAD"
24: android:layout_width="wrap_content"
25: android:layout_height="wrap_content"
26: android:layout_alignLeft="@+id/SAVE"
27: android:layout_below="@+id/SAVE"
28: android:layout_marginTop="46dp"
29: android:text="LOAD DATA" />
30: <Button
31: android:id="@+id/SAVE"
32: android:layout_width="wrap_content"
33: android:layout_height="wrap_content"
34: android:layout_below="@+id/msg"
35: android:layout_centerHorizontal="true"
36: android:layout_marginTop="23dp"
37: android:text="SAVE DATA" />
38: </RelativeLayout>
MainActivity.java
1: package com.filedemo;
2: import java.io.FileInputStream;
3: import java.io.FileNotFoundException;
4: import java.io.FileOutputStream;
5: import java.io.IOException;
6: import java.io.InputStreamReader;
7: import java.io.OutputStreamWriter;
8: import android.app.Activity;
9: import android.os.Bundle;
10: import android.view.Menu;
11: import android.view.View;
12: import android.view.View.OnClickListener;
13: import android.widget.Button;
14: import android.widget.EditText;
15: import android.widget.Toast;
16: public class MainActivity extends Activity {
17: Button save,load;
18: EditText message;
19: String Message;
20: int data_block = 100;
21: @Override
22: protected void onCreate(Bundle savedInstanceState) {
23: super.onCreate(savedInstanceState);
24: setContentView(R.layout.activity_main);
25: save=(Button) findViewById(R.id.SAVE);
26: load = (Button) findViewById(R.id.LOAD);
27: message = (EditText) findViewById(R.id.msg);
28: save.setOnClickListener(new OnClickListener() {
29: @Override
30: public void onClick(View v) {
31: // TODO Auto-generated method stub
32: Message = message.getText().toString();
33: try {
34: FileOutputStream fou = openFileOutput("text.txt", MODE_WORLD_READABLE);
35: OutputStreamWriter osw = new OutputStreamWriter(fou);
36: try {
37: osw.write(Message);
38: osw.flush();
39: osw.close();
40: Toast.makeText(getBaseContext(), "Data saved", Toast.LENGTH_LONG).show();
41: } catch (IOException e) {
42: // TODO Auto-generated catch block
43: e.printStackTrace();
44: }
45: } catch (FileNotFoundException e) {
46: // TODO Auto-generated catch block
47: e.printStackTrace();
48: }
49: }
50: });
51: load.setOnClickListener(new OnClickListener() {
52: @Override
53: public void onClick(View v) {
54: // TODO Auto-generated method stub
55: try {
56: FileInputStream fis = openFileInput("text.txt");
57: InputStreamReader isr = new InputStreamReader(fis);
58: char[] data = new char[data_block];
59: String final_data="";
60: int size;
61: try {
62: while((size = isr.read(data))>0)
63: {
64: String read_data = String.copyValueOf(data, 0, size);
65: final_data+= read_data;
66: data = new char[data_block];
67: }
68: Toast.makeText(getBaseContext(), "Message :"+final_data, Toast.LENGTH_LONG).show();
69: } catch (IOException e) {
70: // TODO Auto-generated catch block
71: e.printStackTrace();
72: }
73: } catch (FileNotFoundException e) {
74: // TODO Auto-generated catch block
75: e.printStackTrace();
76: }
77: }
78: });
79: }
80: @Override
81: public boolean onCreateOptionsMenu(Menu menu) {
82: // Inflate the menu; this adds items to the action bar if it is present.
83: getMenuInflater().inflate(R.menu.main, menu);
84: return true;
85: }
86: }