Java: Converting Class member variables/values into Map - Reflection

Question

I have an instance of a class for which I would like to create a Map which has Key as each class variable name and its Value as the value in that class variable?

I tried to use the following but it doesn't seem to work. It does not go into either the if() or the else if() section. And the maps remain empty.

Could someone figure out the issue here? Thanks

public class ClassA {
    private String optionOne = "1";
    private Int optionTwo = 2;

}


        Map<String, String> map = new HashMap<>();
        Map<String, Integer> mapInt = new HashMap<>();

        for (Field field : ClassA.class.getFields()) {
            field.setAccessible(true);
            if (field.getType().equals(String.class)){
                map.put(field.getName(), (String) field.get(object));
            } else if (field.getType().equals(Integer.class)) {
                mapInt.put(field.getName(), (Integer) field.get(object));
            }
        }

Use getDeclaredFields, and it is int.class not Integer.class. — zhh
– zhh, Commented Jul 19, 2018 at 5:28
@zhh ok that works for String.class now. But the int variables are not going into mapInt. is the equality check correct? — Sunny
– Sunny, Commented Jul 19, 2018 at 5:36

zhh · Accepted Answer · 2018-07-19 05:41:43Z

2

Change getFields to getDeclaredFields and Integer.class to int.class since field optionTwo is int not Integer.

Map<String, String> map = new HashMap<>();
Map<String, Integer> mapInt = new HashMap<>();

for (Field field : ClassA.class.getDeclaredFields()) {
    field.setAccessible(true);
    if (field.getType().equals(String.class)){
        map.put(field.getName(), (String) field.get(object));
    } else if (field.getType().equals(int.class)) {
        mapInt.put(field.getName(), (Integer) field.get(object));
    }
}

answered Jul 19, 2018 at 5:41

zhh

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Sunny · Accepted Answer · 2018-07-19 05:41:56Z

0

With the help of @zhh I was able to fix the issue as follows:

ClassA.class.getDeclaredFields() instead of ClassA.class.getFields()
Integer.TYPE instead of Integer.class

 for (Field field : ClassA.class.getDeclaredFields()) {
                field.setAccessible(true);
                if (field.getType().equals(String.class)){
                    map.put(field.getName(), (String) field.get(object));
                } else if (field.getType().equals(Integer.TYPE)) {
                    mapInt.put(field.getName(), (Integer) field.get(object));
                }
            }

answered Jul 19, 2018 at 5:41

Sunny

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