java going through array field without creating new instance

Question

I'm trying to write a method which gets an Object and does some logic with the Object's fields.

My method looks like:

public void exampleCast(Object obj) {
    Field[] fields = obj.getClass().getFields();
    for (Field field : fields) {                    
        if (field.getClass().isArray()) {
        
        /*
            HOW CAN I GO OVER THE ARRAY FIELDS , WITHOUT CREATING NEW INSATCNE ?
            SOMETHING LIKE:
            for (int i = 0; i < array.length; i++) {
               array[i] ...
            }
            
        */  
        } else {
            ...
            ...
        }
    }
}

And an example of objects:

class TBD1 {
    public int x;
    public int y;
    public int[] arrInt = new int[10];
    public byte[] arrByte = new byte[10];
}

And the call to my method:

TBD1 tbd1 = new TBD1();
exampleCast(tbd1);

In my method, I don't know how can I get the array values without create new instance (using the newInstance method) Is it possible? (please see the comment I wrote in my example)

I have read those 2 websites:

... but I didn't get what I wanted to.

Elliott Frisch · Accepted Answer · 2014-11-21 20:12:28Z

3

If I understand your question, you might use java.lang.reflect.Array and something like

if (field.getType().isArray()) { // <-- should be getType(), thx @Pshemo
    Object array = field.get(obj);
    int len = Array.getLength(array);
    for (int i = 0; i < len; i++) {
        Object v = Array.get(array, i);
        System.out.println(v);
    }
} // ...

edited Nov 21, 2014 at 20:12

answered Nov 21, 2014 at 20:06

Elliott Frisch

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1 Comment

Pshemo Over a year ago

Shouldn't it be getType instead of getClass? If I am not mistaken getClass invoked on Field instance will return us Field.class which is definitely not an array. What we want to do is check if type of variable is array.

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