Creating an array of fields in Java

Question

I am trying to implement program that will create an array out of the fields of a certain class and then access each field

I have the following class:

public class Example {

  public int[] a = {1,2,3};
  public int[] b = {1,1,1};
  public int[] c = {2,2,2};
}

In a different class I want to access all of these fields and place them into the array "testArray"

import java.lang.reflect.Field;
public class Test { 

  Example t = new Example();
  Field[] testArray = t.getClass().getFields();

  for (Field elem: testArray) {
   // access the fields
  }

}

How can I access the fields this way?

NOTE: for some reasone this gives me an error of Syntax error on token ";", { expected after this token

@dasblinkenlight thank you for the small fix, but it still gives me the same error — jean
– jean, Commented Oct 29, 2014 at 2:55

Sergey Kalinichenko · Accepted Answer · 2014-10-29 03:00:43Z

3

You are almost there: once you got an array of fields, call get on each one, passing the instance of the object from which you wish to get the property (in this case, that would be t):

Object[] fieldsOfT = new Object[testArray.length];
int i = 0;
for (Field f : testArray) {
    fieldsOfT[i++] = f.get(t);
}
for (Object v : fieldsOfT) {
    System.out.println(v);
}

Demo.

Of course this would not print pretty representations of the objects, because int[] arrays do not provide a meaningful toString, but you have the value there as an object, so you can cast it, and print the values as needed.

answered Oct 29, 2014 at 3:00

Sergey Kalinichenko

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Comments

akodiakson · Accepted Answer · 2014-10-29 03:11:30Z

1

You get an error because none of the code lives inside of a method. Move it into a test method.

answered Oct 29, 2014 at 3:11

akodiakson

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