how can I make charAt method work with arrays in java?

Question

can someone help me with this problem ? i have to make method charAt to work but i dont know how..

class AsciiCharSequence implements java.lang.CharSequence/* extends/implements */ {
    // implementation
    byte[] array;

    public AsciiCharSequence(byte[] array) {
        this.array = array.clone();
    }

    @Override
    public int length() {
        return array.length;
    }

    *@Override
    public char charAt(int i) {
        return (char) array.length(i);
    }*

`return (char) array[i];` (although the explicit cast is unnecessary). — Andy Turner, May 04 '20 at 09:26

score 0 · Answer 1 · answered May 04 '20 at 09:34

0

Try this:

@Override
public char charAt(int i) {
    return (char) array[i];
}

Since you have an array and want to return the character at a particular array. In your question you are not returning a particular index value.

answered May 04 '20 at 09:34

beingshuchi

109
1
10

Although explicit casting is not a good practice, try avoiding it! – beingshuchi May 04 '20 at 09:36

score 0 · Answer 2 · answered May 04 '20 at 09:40

Use [] to access element in the array. But do not forget about throwing required exception, like it declared in CharSequence documentation (if you access not correct element in an array, another type of exception will be thorwn).

public class AsciiCharSequence implements CharSequence {

    private static final char[] EMPTY_ARRAY = new char[0];

    private final char[] arr;

    public AsciiCharSequence(char[] arr) {
        this.arr = arr == null || arr.length == 0 ? EMPTY_ARRAY : Arrays.copyOf(arr, arr.length);
    }

    private AsciiCharSequence(char[] arr, int start, int end) {
        this.arr = arr == null || arr.length == 0 || start == end ? EMPTY_ARRAY : Arrays.copyOfRange(arr, start, end);
    }

    @Override
    public int length() {
        return arr.length;
    }

    @Override
    public char charAt(int i) {
        if (i < 0 || i >= length())
            throw new IndexOutOfBoundsException();

        return arr[i];
    }

    @Override
    public AsciiCharSequence subSequence(int start, int end) {
        if (start < 0 || end < 0)
            throw new IndexOutOfBoundsException();
        if (end > length())
            throw new IndexOutOfBoundsException();
        if (start > end)
            throw new IndexOutOfBoundsException();

        return new AsciiCharSequence(arr, start, end);
    }

    @Override
    public String toString() {
        return IntStream.range(0, arr.length).mapToObj(i -> String.valueOf(arr[i])).collect(Collectors.joining());
    }
}

score 0 · Answer 3 · answered May 04 '20 at 10:30

For better understanding about character set can be refer below code from AbstractStringBuilder

 @Override
public char charAt(int index) {
    checkIndex(index, count);
    if (isLatin1()) {
        return (char)(value[index] & 0xff);
    }
    return StringUTF16.charAt(value, index);
}

how can I make charAt method work with arrays in java?

3 Answers3