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  2. How to read a selected text file from sdcard on android

How to read a selected text file from sdcard on android

由 好久不见. 提交于 2019-11-28 00:15:06

Try this code:

package com.javasamples;
import java.io.*;
import android.app.Activity;
import android.os.Bundle;
import android.view.*;
import android.view.View.OnClickListener;
import android.widget.*;

public class FileDemo2 extends Activity {
    // GUI controls
    EditText txtData;
    Button btnWriteSDFile;
    Button btnReadSDFile;
    Button btnClearScreen;
    Button btnClose;

    @Override
    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    // bind GUI elements with local controls
    txtData = (EditText) findViewById(R.id.txtData);
    txtData.setHint("Enter some lines of data here...");

    btnWriteSDFile = (Button) findViewById(R.id.btnWriteSDFile);
    btnWriteSDFile.setOnClickListener(new OnClickListener() {

    public void onClick(View v) {
        // write on SD card file data in the text box
        try {
            File myFile = new File("/sdcard/mysdfile.txt");
            myFile.createNewFile();
            FileOutputStream fOut = new FileOutputStream(myFile);
            OutputStreamWriter myOutWriter = 
                                    new OutputStreamWriter(fOut);
            myOutWriter.append(txtData.getText());
            myOutWriter.close();
            fOut.close();
            Toast.makeText(getBaseContext(),
                    "Done writing SD 'mysdfile.txt'",
                    Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            Toast.makeText(getBaseContext(), e.getMessage(),
                    Toast.LENGTH_SHORT).show();
        }
    }// onClick
    }); // btnWriteSDFile

        btnReadSDFile = (Button) findViewById(R.id.btnReadSDFile);
        btnReadSDFile.setOnClickListener(new OnClickListener() {

        public void onClick(View v) {
            // write on SD card file data in the text box
        try {
            File myFile = new File("/sdcard/mysdfile.txt");
            FileInputStream fIn = new FileInputStream(myFile);
            BufferedReader myReader = new BufferedReader(
                    new InputStreamReader(fIn));
            String aDataRow = "";
            String aBuffer = "";
            while ((aDataRow = myReader.readLine()) != null) {
                aBuffer += aDataRow + "\n";
            }
            txtData.setText(aBuffer);
            myReader.close();
            Toast.makeText(getBaseContext(),
                    "Done reading SD 'mysdfile.txt'",
                    Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            Toast.makeText(getBaseContext(), e.getMessage(),
                    Toast.LENGTH_SHORT).show();
        }
        }// onClick
        }); // btnReadSDFile

        btnClearScreen = (Button) findViewById(R.id.btnClearScreen);
        btnClearScreen.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                // clear text box
                txtData.setText("");
            }
        }); // btnClearScreen

        btnClose = (Button) findViewById(R.id.btnClose);
        btnClose.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                // clear text box
                finish();
            }
        }); // btnClose

    }// onCreate

}// AndSDcard

the layout file is 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:id="@+id/widget28"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#ff0000ff"
android:orientation="vertical"
xmlns:android="http://schemas.android.com/apk/res/android"
>
<EditText
android:id="@+id/txtData"
android:layout_width="fill_parent"
android:layout_height="180px"
android:textSize="18sp"  />

<Button
android:id="@+id/btnWriteSDFile"
android:layout_width="143px"
android:layout_height="44px"
android:text="1. Write SD File"  />

<Button
android:id="@+id/btnClearScreen"
android:layout_width="141px"
android:layout_height="42px"
android:text="2. Clear Screen"  />

<Button
android:id="@+id/btnReadSDFile"
android:layout_width="140px"
android:layout_height="42px"
android:text="3. Read SD File"  />

<Button
android:id="@+id/btnClose"
android:layout_width="141px"
android:layout_height="43px"
android:text="4. Close" />

</LinearLayout>

I used this code to read a text file in SD card,

public class ReadFileSDCardActivity extends Activity {  
    /** Called when the activity is first created. */  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  

        //Find the view by its id  
        TextView tv = (TextView)findViewById(R.id.fileContent);  

        File dir = Environment.getExternalStorageDirectory();  
        //File yourFile = new File(dir, "path/to/the/file/inside/the/sdcard.ext");  

        //Get the text file  
        File file = new File(dir,"text.txt");  
        // i have kept text.txt in the sd-card  

        if(file.exists())   // check if file exist  
        {  
              //Read text from file  
            StringBuilder text = new StringBuilder();  

            try {  
                BufferedReader br = new BufferedReader(new FileReader(file));  
                String line;  

                while ((line = br.readLine()) != null) {  
                    text.append(line);  
                    text.append('\n');  
                }  
            }  
            catch (IOException e) {  
                //You'll need to add proper error handling here  
            }  
            //Set the text  
            tv.setText(text);  
        }  
        else  
        {  
            tv.setText("Sorry file doesn't exist!!");  
        }  
     }  
}

first you have to give an id to your textview into the load.xml file and define the textview inside a linear layout. like this

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
<TextView android:id="@+id/tv1
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" 
        android:textSize="18sp"/>

now you have to set the layout of your activity.you can do this in the onCreate() method only.

setContentView(R.layout.load);

now make a TextVew object like this.

TextView tview = (TextView) findViewById(R.id.tv1);

now you have to read the text file using FileInputStream and keep it into a string variable.

after that you can assign the string to the text view.

tview.setText(string variable name);
标签
android
file
text
sd-card
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