List files in directory with specified type

The example List all 'jpg' files in given directoty:

 private File[] getJpgFiles(File f){
  File[] files = f.listFiles(new FilenameFilter(){

   @Override
   public boolean accept(File dir, String filename) {
    return filename.toLowerCase().endsWith(".jpg");
   }});
  
  return files;
 }

Convert between Uri and file path, and load Bitmap from.

What return from Android build-in Gallery App is Uri, in the form of "content://media/...". This exercise demonstrate how to convert the Uri to real file path, in the form of "/storage/sdcard0/...". and convert back to Uri, in the form of "file:///storage/sdcard0/...".  All the three form refer to the same file.

And also demonstrate how to load bitmap from the Uri(s) and file path, then display in ImageView.

package com.example.androiduri;

import java.io.File;
import java.io.FileNotFoundException;

import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.provider.MediaStore.Images;
import android.support.v4.content.CursorLoader;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;

public class MainActivity extends Activity {

 Button btnSelFile;
 TextView text1, text2, text3, note;
 ImageView image;
 
 Uri orgUri, uriFromPath;
 String convertedPath;
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  btnSelFile = (Button)findViewById(R.id.selfile);
  text1 = (TextView)findViewById(R.id.text1);
  text2 = (TextView)findViewById(R.id.text2);
  text3 = (TextView)findViewById(R.id.text3);
  note = (TextView)findViewById(R.id.note);
  image = (ImageView)findViewById(R.id.image);
  
  btnSelFile.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View arg0) {
    Intent intent = new Intent(Intent.ACTION_PICK, 
      Images.Media.EXTERNAL_CONTENT_URI);
    startActivityForResult(intent, 0);
   }});
  
  text1.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View v) {
    image.setImageBitmap(null);
    note.setText("by Returned Uri");
    
    try {
     Bitmap bm = BitmapFactory.decodeStream(
       getContentResolver().openInputStream(orgUri));
     image.setImageBitmap(bm); 
    } catch (FileNotFoundException e) {
     e.printStackTrace(); 
    }
   }});
  
  text2.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View v) {
    image.setImageBitmap(null);
    note.setText("by Real Path");
    Bitmap bm = BitmapFactory.decodeFile(convertedPath);
    image.setImageBitmap(bm);
   }});
  
  text3.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View v) {
    image.setImageBitmap(null);
    note.setText("by Back Uri");
    
    try {
     Bitmap bm = BitmapFactory.decodeStream(
       getContentResolver().openInputStream(uriFromPath));
     image.setImageBitmap(bm); 
    } catch (FileNotFoundException e) {
     e.printStackTrace(); 
    }
   }});
 }

 @Override
 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  super.onActivityResult(requestCode, resultCode, data);
  
  if(resultCode == RESULT_OK){
   
   image.setImageBitmap(null);
   
   //Uri return from external activity
   orgUri = data.getData();
   text1.setText("Returned Uri: " + orgUri.toString() + "\n");
   
   //path converted from Uri
   convertedPath = getRealPathFromURI(orgUri);
   text2.setText("Real Path: " + convertedPath + "\n");
   
   //Uri convert back again from path
   uriFromPath = Uri.fromFile(new File(convertedPath));
   text3.setText("Back Uri: " + uriFromPath.toString() + "\n");
  }
  
 }

 public String getRealPathFromURI(Uri contentUri) {
  String[] proj = { MediaStore.Images.Media.DATA };
  
  //This method was deprecated in API level 11
  //Cursor cursor = managedQuery(contentUri, proj, null, null, null);
  
  CursorLoader cursorLoader = new CursorLoader(
            this, 
            contentUri, proj, null, null, null);        
  Cursor cursor = cursorLoader.loadInBackground();
  
  int column_index = 
    cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
  cursor.moveToFirst();
  return cursor.getString(column_index); 
 }
 
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="android-er.blogspot.com" />
    <Button 
        android:id="@+id/selfile"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Select File" />
    <TextView
        android:id="@+id/text1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/text2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/text3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/note"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <ImageView
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

Please notice that the code haven't handle resize on the bitmap. If you load with a large picture, OutOfMemoryError will be caused.

Download the files.

Related: Load picture with Intent.ACTION_GET_CONTENT

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Update@2014-12-27: Not work on KitKat now!

Permission of "android.permission.READ_EXTERNAL_STORAGE" have to be added in AndroidManifest.xml. Refer to Update "android.permission.READ_EXTERNAL_STORAGE" for KitKat.