Question

My lack of Java is biting me on the heels again. I have the following member function:

protected void setData(Map<String, String[]> data) {
    Class thisClass = this.getClass();
    for(Map.Entry<String, String[]> item : data.entrySet()) {
        try {
            Field field = thisClass.getDeclaredField(item.getKey());
            try {
                if(field.getType().getName().equals("java.lang.Long")) {
                    // EXCEPTION HERE!!!
                    field.setLong(this, Long.valueOf(item.getValue()[0]) );
                }...
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        } catch (NoSuchFieldException e) {
            // Skip this field...
            continue;
        }
    }
}

I keep on getting an IllegalArgumentException, and i don’t fully understand why. Can anyone offer some insight?

The function takes a map, which it iterates, and assigns the values to “this” by checking if the field exists on “this” and if so, attempts to call field.set().

Answer 1

setLong(..) tries to set a primitive value, and your fields is java.lang.Long. Always use the set(..) method for non-primitives. For primitives getType().getName() would return int, long, etc.

Initial answer: You need to make the field accessible: field.setAccessible(true)