CODEWITHSUNDEEP
javaandroidlistandroid-studio
Peter
Peter

Reputation: 37

How to add certain paths in the List?

Code below counts files with certain name. TypeCount is then some number (four for example).

File dir = new File(Environment.getExternalStorageDirectory().toString(), "/AppDir/" );

File[] files=dir.listFiles();
int typeCount = 0;
String type = "dog";


for (int i=0; i<files.length; i++) {
     File file = files[i];
     String filepath = file.getPath();
        if(filepath.contains(type)){
            typeCount = typeCount + 1;
          }
    }

In this code I want to put every path (File) in the List<File>. But when I set typeCount to size of the List I get always zero instead.

File dir = new File(Environment.getExternalStorageDirectory().toString(), "/AppDir/" );

File dir = new File(Environment.getExternalStorageDirectory().toString(), "/AppDir/" );

File[] files=dir.listFiles();

int typeCount = 0;

String typeype = "dog";

List<File> myList;
myList = new List<File>() {
    @Override
    public void add(int i, File file) {

    }

    @Override
    public boolean add(File file) {
        return false;
    }

    @Override
    public boolean addAll(int i, Collection<? extends File> collection) {
        return false;
    }

    @Override
    public boolean addAll(Collection<? extends File> collection) {
        return false;
    }

    @Override
    public void clear() {

    }

    @Override
    public boolean contains(Object o) {
        return false;
    }

    @Override
    public boolean containsAll(Collection<?> collection) {
        return false;
    }

    @Override
    public File get(int i) {
        return null;
    }

    @Override
    public int indexOf(Object o) {
        return 0;
    }

    @Override
    public boolean isEmpty() {
        return false;
    }

    @NonNull
    @Override
    public Iterator<File> iterator() {
        return null;
    }

    @Override
    public int lastIndexOf(Object o) {
        return 0;
    }

    @Override
    public ListIterator<File> listIterator() {
        return null;
    }

    @NonNull
    @Override
    public ListIterator<File> listIterator(int i) {
        return null;
    }

    @Override
    public File remove(int i) {
        return null;
    }

    @Override
    public boolean remove(Object o) {
        return false;
    }

    @Override
    public boolean removeAll(Collection<?> collection) {
        return false;
    }

    @Override
    public boolean retainAll(Collection<?> collection) {
        return false;
    }

    @Override
    public File set(int i, File file) {
        return null;
    }

    @Override
    public int size() {
        return 0;
    }

    @NonNull
    @Override
    public List<File> subList(int i, int i1) {
        return null;
    }

    @NonNull
    @Override
    public Object[] toArray() {
        return new Object[0];
    }

    @NonNull
    @Override
    public <T> T[] toArray(T[] ts) {
        return null;
    }
};

for (int i=0; i<files.length; i++){
    File file = files[i];
    String filepath = file.getPath();
    if(filepath.contains(type)){
        myList.add(file);
    }
}

typeCount = myList.size();

What is wrong here?
(And a little off topic - Is path written correctly? I'm not sure about it.)

Upvotes: 0

Views: 60

Answers (1)

Blo
Blo

Reputation: 11978

This method size() will always print 0 because your own List implementation has a wrong returning statement:

@Override
public int size() {
    return 0; // Oops!
}

Another thing too, you don't really insert anything in your List because of this:

@Override
public boolean add(File file) {
    return false; // Hum...
}

Your methods aren't completed yet to execute the same tasks as a normal List. You better should use ArrayList<File> or List<File> which will have all the right methods and won't require hard work from you. Don't reinvent the wheel ;)

Finally, the path are right declared, but you should test if the files are presents in the folder before executing the code. Something as follows:

File[] files = dir.listFiles();
if (files.length > 0) {
    // loop and add to a list
}

Upvotes: 1

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