You have to iterate the files array and call getName() for each file:

String[] names = new String[files.length];
for (int i = 0; i < files.length; i++) {
   names[i] = files[i].getName();
}

You don't need to convert the whole array. Just call File's getAbsolutePath() method:

driver.findElement(By.id(id1)).sendKeys(listOfFiles[1].getAbsolutePath());

But if you do want to convert the whole array, here is the Java 8 way to do this (simplified by @RemigiusStalder):

String listOfPaths[] = Arrays.stream(listOfFiles).map(File::getAbsolutePath)
        .toArray(String[]::new);

Assuming that it's the file paths you want, just create a String array of the same size, and iterate through the arrays getting the file paths and putting them in the String array:

String[] myStrings = new String[myFiles.length()];
for( int i = 0; i < myFiles.length(); i++ )
{
    myStrings[i] = myFiles[i].getPath();
}

Same for file names or whatever, just call the method for the string you want. I haven't written Java for a while, so the syntax might be slightly off, but that should give you the idea.

First, this is not a good application of the enhanced for-loop which masks the iterator variable. Second, I'm not sure which FTPFile implementation you're using, but I'll offer this snippet, assuming your use of Apache Commons FTPFile.

String[] strings = new String[files.length];
for(int i = 0; i < files.length; i++){
    strings[i] = files[i].getName(); // or whatever method call your FTPFile has
}

Here is some example code to help you get started:

package com.acme;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class FileArrayProvider {

    public String[] readLines(String filename) throws IOException {
        FileReader fileReader = new FileReader(filename);
        BufferedReader bufferedReader = new BufferedReader(fileReader);
        List<String> lines = new ArrayList<String>();
        String line = null;
        while ((line = bufferedReader.readLine()) != null) {
            lines.add(line);
        }
        bufferedReader.close();
        return lines.toArray(new String[lines.size()]);
    }
}

And an example unit test:

package com.acme;

import java.io.IOException;

import org.junit.Test;

public class FileArrayProviderTest {

    @Test
    public void testFileArrayProvider() throws IOException {
        FileArrayProvider fap = new FileArrayProvider();
        String[] lines = fap
                .readLines("src/main/java/com/acme/FileArrayProvider.java");
        for (String line : lines) {
            System.out.println(line);
        }
    }
}

Hope this helps.

If you use Java 7 it can be done in two lines thanks to the Files#readAllLines method:

List<String> lines = Files.readAllLines(yourFile, charset);
String[] arr = lines.toArray(new String[lines.size()]);

Stored as strings:

public class ReadTemps {

    public static void main(String[] args) throws IOException {
    // TODO code application logic here

    // // read KeyWestTemp.txt

    // create token1
    String token1 = "";

    // for-each loop for calculating heat index of May - October

    // create Scanner inFile1
    Scanner inFile1 = new Scanner(new File("KeyWestTemp.txt")).useDelimiter(",\\s*");

    // Original answer used LinkedList, but probably preferable to use ArrayList in most cases
    // List<String> temps = new LinkedList<String>();
    List<String> temps = new ArrayList<String>();

    // while loop
    while (inFile1.hasNext()) {
      // find next line
      token1 = inFile1.next();
      temps.add(token1);
    }
    inFile1.close();

    String[] tempsArray = temps.toArray(new String[0]);

    for (String s : tempsArray) {
      System.out.println(s);
    }
  }
}

For floats:

import java.io.File;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.Scanner;

public class ReadTemps {

  public static void main(String[] args) throws IOException {
    // TODO code application logic here

    // // read KeyWestTemp.txt

    // create token1

    // for-each loop for calculating heat index of May - October

    // create Scanner inFile1
    Scanner inFile1 = new Scanner(new File("KeyWestTemp.txt")).useDelimiter(",\\s*");


    // Original answer used LinkedList, but probably preferable to use ArrayList in most cases
    // List<Float> temps = new LinkedList<Float>();
    List<Float> temps = new ArrayList<Float>();

    // while loop
    while (inFile1.hasNext()) {
      // find next line
      float token1 = inFile1.nextFloat();
      temps.add(token1);
    }
    inFile1.close();

    Float[] tempsArray = temps.toArray(new Float[0]);

    for (Float s : tempsArray) {
      System.out.println(s);
    }
  }
}

You can't cast a File to String, cause a File is not a String.

However File has a few methods (getName(), getAbsolutePath()) that return a String.

So you can do :

String[] stringArray = new String[objectArray.length];
for (int i = 0; i < objectArray.length; i++) stringArray[i] = objectArray[i].getAbsolutePath();

Use a java.util.Scanner and java.util.List.

Scanner sc = new Scanner(new File(filename));
List<String> lines = new ArrayList<String>();
while (sc.hasNextLine()) {
  lines.add(sc.nextLine());
}

String[] arr = lines.toArray(new String[0]);

Another alternative to System.arraycopy:

String[] stringArray = Arrays.copyOf(objectArray, objectArray.length, String[].class);

The newer classes Path and Files will do.

Path path = Paths.get("C:\\Users\\emily\\Documents\\Parts.txt");
try {
    List<String> lines = Files.readAllLines(path, Charset.defaultCharset());
    String[] array = lines.toArray(new String[lines.size()]);
    ...
} catch (IOException e) {
    //Logger.getLogger(getClass().getName()).log(Level.SEVERE,
    //                                           path.toString(), e);
    System.err.println("Could not read file: " + e.getMessage());
}

Best would be to use just the List.

Add the handling of a possible IOException, probably when the file could not be read.