问题
I am a newbie. I have an EditText and a Browse Button to explore Folders and select files only. From the Browse Button, when a file is clicked it stores the folder path in which that file is in one string and the file name without extension in other string, which I am using to store, either of these two, in the EditText.
I want to make the file name with the exactly file extension (whether one or two dots), but I don't have any idea how to get the file extension also.
All answers will be appreciated. FileChooser.java
package com.threefriends.filecrypto;
/**
* Created by hp on 01-06-2016.
*/
import java.io.File;
import java.sql.Date;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.text.DateFormat;
import android.os.Bundle;
import android.app.ListActivity;
import android.content.Intent;
import android.view.View;
import android.widget.ListView;
public class FileChooser extends ListActivity {
private File currentDir;
private FileArrayAdapter adapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
currentDir=new File("/sdcard/");
fill(currentDir);
}
private void fill(File f)
{
File[]dirs=f.listFiles();
this.setTitle("Current Dir: "+f.getName());
List<Item>dir=new ArrayList<Item>();
List<Item>fls=new ArrayList<Item>();
try{
for(File ff: dirs)
{
Date lastModDate=new Date(ff.lastModified());
DateFormat formater=DateFormat.getDateTimeInstance();
String date_modify=formater.format(lastModDate);
if(ff.isDirectory()){
File[] fbuf=ff.listFiles();
int buf=0;
if(fbuf != null){
buf=fbuf.length;
}
else
buf=0;
String num_item=String.valueOf(buf);
if(buf == 0)
num_item=num_item+" item";
else
num_item = num_item+" items";
//String formated = lastModDate.toString();
dir.add(new Item(ff.getName(), num_item, date_modify, ff.getAbsolutePath(), "directory_icon"));
}
else
{
fls.add(new Item(ff.getName(), ff.length()+" Byte", date_modify, ff.getAbsolutePath(), "file_icon"));
}
}
}catch(Exception e)
{
}
Collections.sort(dir);
Collections.sort(fls);
dir.addAll(fls);
if(!f.getName().equalsIgnoreCase("sdcard"))
dir.add(0, new Item("..", "Parent Directory", "", f.getParent(), "directory_up"));
adapter=new FileArrayAdapter(FileChooser.this, R.layout.file_view, dir);
this.setListAdapter(adapter);
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id){
// TODO Auto-generated method stub
super.onListItemClick(l, v, position, id);
Item o = adapter.getItem(position);
if(o.getImage().equalsIgnoreCase("directory_icon") || o.getImage().equalsIgnoreCase("directory_up")){
currentDir=new File(o.getPath());
fill(currentDir);
}
else
{
onFileClick(o);
}
}
private void onFileClick(Item o)
{
//Toast.makeText(this, "Folder Clicked: "+ currentDir, Toast.LENGTH_SHORT).show();
Intent intent = new Intent();
intent.putExtra("GetPath", currentDir.toString());
intent.putExtra("GetFileName", o.getName());
setResult(RESULT_OK, intent);
finish();
}
}
Part of MainActivity.java
//Defined for file edittext.
EditText editText2;
private static String TAG = MainFragment.class.getSimpleName(); //For File Exploring.
private static final int REQUEST_PATH = 1;
String curFileName;
String filePath;
EditText edittext;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.fragment_main, container, false);
edittext = (EditText) view.findViewById(R.id.editText); //Done for File Exploring, EditText, Browse Button.
Button b1 = (Button) view.findViewById(R.id.skipButton);
b1.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
Intent intent1 = new Intent(v.getContext(), FileChooser.class);
startActivityForResult(intent1, REQUEST_PATH);
}
}
);
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
// See which child activity is calling us back.
if (requestCode == REQUEST_PATH)
{
if (resultCode == Activity.RESULT_OK)
{
curFileName = data.getStringExtra("GetFileName");
filePath=data.getStringExtra("GetPath");
edittext.setText(filePath);
}
}
}
回答1:
lots of ways . here are 2 sample-
String someFilepath = "image.fromyesterday.test.jpg";
String extension = someFilepath.substring(someFilepath.lastIndexOf("."));
So in you case, it should be something like that
String extension = ff.getAbsolutePath().substring(ff.getAbsolutePath().lastIndexOf("."));
In case if you don't want to do it yourself-
use FilenameUtils.getExtension from Apache Commons IO-
String extension = FilenameUtils.getExtension("/path/to/file/mytext.txt");
or in your case -
String extension = FilenameUtils.getExtension(ff.getAbsolutePath());
回答2:
You could just do it with one line of code using MIME Type Map.
First grab the file:
Uri file = Uri.fromFile(new File(filePath));
Then
String fileExt = MimeTypeMap.getFileExtensionFromUrl(file.toString());
回答3:
You can put your code in your activity like this:
private String getfileExtension(Uri uri)
{
String extension;
ContentResolver contentResolver = getContentResolver();
MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton();
extension= mimeTypeMap.getExtensionFromMimeType(contentResolver.getType(uri));
return extension;
}
"uri" is the file uri from the result of "Browse button" selected file
回答4:
Koltin Approach:
val fileExtention: String = file.extension
Check this: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.io/java.io.-file/extension.html
回答5:
Function:
public String getExt(String filePath){
int strLength = filePath.lastIndexOf(".");
if(strLength > 0)
return filePath.substring(strLength + 1).toLowerCase();
return null;
}
Usage:
String ext = getExt(path);
if(ext != null && ext.equals("txt")){
// do anything
}
PS: If you don't use toLowerCase(), possible the function returns upper and lower cases (dependent the exists file).
来源：https://stackoverflow.com/questions/37951869/how-to-get-the-file-extension-in-android