Question

I have an object of type Object, and I want to return a String representation of it using the toString() method, except if it is an array, I want to return Arrays.toString() of the object (I don’t need a deepToString).

I thought about using this :

public static String getValueAsString(Object value){
    if(value != null && value.getClass().isArray()){
        if(value instanceof Object[])
            return Arrays.toString((Object[])value);
        else if(value instanceof int[])
            return Arrays.toString((int[])value);
        else ...
    }else
        return String.valueOf(value);
}

The problem is that I can detect it is an array, but I have to handle all the different primitive array …

Is there a cleaner way to achieve this ? using core methods or reflection ?

Answer 1

You can use the generic Array class to iterate any array like this:

private static String toStr(Object o) {
    if (o == null || !o.getClass().isArray()) {
        return String.valueOf(o);

    } else {
        final int len = Array.getLength(o);

        StringBuilder sb = new StringBuilder('[');
        for (int i = 0; i < len; i++)
            sb.append(Array.get(o, i)).append(i + 1 < len ? ", " : "");

        return sb.append(']').toString();
    }
}

---

Example:

public static void main(String[] args) {

    System.out.println(toStr(new int[] {1,2,3}));
    System.out.println(toStr(new double[] {4.0, 5.0, 6.0}));
    System.out.println(toStr(new Object[] {null, 7, 8.0}));
    System.out.println(toStr("Hello World!"));
}

Outputs:

[1, 2, 3]
[4.0, 5.0, 6.0]
[null, 7, 8.0]
Hello World!