What is a short-hand method for creating a of key/value pairs from a class instance variables?

Question

What should be a best way to create key/value pairs for all the string instance variables of a class? Is there any library exists doing such a task?

I am doing the same using a reflection based backward look-up. But it seems doing to much work.

For example:

I have a class

public class Account implements ManagedEntity {

private String accountNumber;

public Account(String accountNumber) {
    this.accountNumber = accountNumber;
}
}

If an instance of Account class is created like blelow, Account ac = new Account("abc");

The output map should be like: [{"accountNumber", "abc"}].

What do you need this for? Are you trying to build a Map or a String? — Peter Lawrey, Sep 03 '12 at 14:50
Seems like he wants to build a map, but the question doesn't make much sense: what will comprise these key/value pairs besides the string instance variable? In other words, you will map what to what? — arshajii, Sep 03 '12 at 14:53
@A.R.S Please make a difference between "The question doesn't make much sense" and "I cannot imagine a use case for what you are trying to achieve". — Zeemee, Sep 03 '12 at 14:58
Perhaps BeanUtils is what you want. http://stackoverflow.com/questions/5856895/java-reflection-beans-property-api — Peter Lawrey, Sep 03 '12 at 14:58
I think that this can be done using `Annotations`, but that too perhaps take as much effort or more as your `reflection` approach. — Curious, Sep 03 '12 at 15:03

score 2 · Accepted Answer · answered Sep 03 '12 at 15:14

As Peter Lawrey already pointed out in one of the comments, if you are looking for a library that can do that transformation for you then one possible answer is Apache Commons BeanUtils:

You could use the BeanUtils class from that library:

Account account = new Account("abc");
Map accountMap = new HashMap();
BeanUtils.populate(account, accountMap);

Or using the BeanMap implementation it would be even easier:

Account account = new Account("abc");
Map accountMap = new BeanMap(account);

score 0 · Answer 2 · edited May 23 '17 at 11:51

0

Like mentioned by Peter Lawrey and here, it would be like

Account ac = new Account("abc");
Map<String, Object> properties = BeanUtils.describe(ac);

To limit it to String properties, you could use a BeanUtilsBean instance, passing a subclass of ConvertUtilsBean to the constructor. The subclass overrides the lookup method, which returns null if the class isn't String.

edited May 23 '17 at 11:51

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answered Sep 03 '12 at 15:17

Zeemee

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What is a short-hand method for creating a of key/value pairs from a class instance variables?

2 Answers2