How To Get FileExplorer History In Android Development

In the previous post “Start activity using intent for specified MIME type”, the app will quit whenever you press the BACK key on list of files in any directory.

Now in this example with the help of stack and onBackPressed() function history can be added on back pressed.

Algorithm:

1.) Create a new project by File-> New -> Android Project name it FileExplorerHistory.

2.) Write following permissions into android manifest.xml:

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

3.) You must have some directories and some files in those directories on your storage media to check the correct output.
4.) Run for output.

Steps:

1.) Create a project named FileExplorerHistory and set the information as stated in the image.

Build Target: Android 4.4
Application Name: FileExplorerHistory
Package Name: com.example. FileExplorerHistory
Activity Name: FileExplorerHistoryActivity

2.) Open FileExplorerHistoryActivity.java file and write following code there:

package com.example.fileexplorerhistory;

import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

import android.app.ListActivity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.webkit.MimeTypeMap;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class FileExplorerHistoryActivity extends ListActivity {

private List<String> fileList = new ArrayList<String>();

Stack<File> history;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

history = new Stack<File>();

File root = new File(Environment
.getExternalStorageDirectory()
.getAbsolutePath());
ListDir(root);

}

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
// TODO Auto-generated method stub
File selected = new File(fileList.get(position));
if(selected.isDirectory()){
ListDir(selected);
}else {
Uri selectedUri = Uri.fromFile(selected);
String fileExtension
= MimeTypeMap.getFileExtensionFromUrl(selectedUri.toString());
String mimeType
= MimeTypeMap.getSingleton().getMimeTypeFromExtension(fileExtension);

Toast.makeText(FileExplorerHistoryActivity.this,
"FileExtension: " + fileExtension + "n" +
"MimeType: " + mimeType,
Toast.LENGTH_LONG).show();

//Start Activity to view the selected file
Intent intent;
intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(selectedUri, mimeType);
startActivity(intent);

}
}

void ListDir(File f){

history.push(f);

File[] files = f.listFiles();
fileList.clear();
for (File file : files){
fileList.add(file.getPath());
}

ArrayAdapter<String> directoryList
= new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, fileList);
setListAdapter(directoryList);
}

@Override
public void onBackPressed() {
// TODO Auto-generated method stub

history.pop(); //remove current directory

if(history.empty()){
super.onBackPressed();
}else{
File selected = history.pop(); //Get the File on Top of history
ListDir(selected);
}
}
}

3.) Compile and build the project.

Output