How to get a method using java reflection with only partial name as a string of the method?

Question

I am trying to invoke a getter of a class, I have only the partial name such as "Name", "age" etc. I need to invoke the method from class like getName/retriveName dynamically based on the getters using java Reflection api.

for eg:

class PersonData{

private String personName;
private int personId;
private int personAge;

public PersonData(){
}

public int getPersonId(){
    return this.personID;
}

public String getPersonName(){
    return this.personName;
}

public int getPersonAge(){
    return this.PersonAge;
}
}

I may get "name"/"Name" based on the user input, I should invoke the method getName() only. Kindly help.

Transform the input to lower case, then capitalize the first letter, then append the resulting String to "getPerson" to get the full method name ? — Arnaud
– Arnaud, Commented Feb 20, 2017 at 9:13

walkeros · Accepted Answer · 2017-02-20 09:25:13Z

4

In java 8 you can do like this:

  public static void main(String[] args) throws Exception {
    final PersonData person = new PersonData("Janek", 111, 59);

    final Method method = getMethodLike("naMe");

    final Object output = method.invoke(person);

    System.out.println("Found method with name: " + method.getName() + " which returned: " + output);


  }

  private static Method getMethodLike(String partOfName) {
    final Optional<Method> matchedMethod = asList(PersonData.class.getDeclaredMethods()).stream().filter(method ->
      method.getName().toLowerCase().indexOf(partOfName.toLowerCase()) >= 0).findAny();

    if (!matchedMethod.isPresent()) {
      throw new RuntimeException("No method containing: " + partOfName);
    }

    return matchedMethod.get();
  }

Outputs: "Found method with name: getPersonName which returned: Janek"

answered Feb 20, 2017 at 9:25

walkeros

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1 Comment

Holger Over a year ago

You can use Arrays.stream(PersonData.class.getDeclaredMethods()) instead of the asList(…).stream() detour.

ΦXocę 웃 Пepeúpa ツ · Accepted Answer · 2017-02-20 09:20:00Z

Ummm,n ot really a goot idea, you have to either GETALL methods and search by name (regex for example) or provide the hole full name of the mothod you want to invoke....

    PersonData i = new PersonData();
    String userInp = "name";
    Class<PersonData> ri = (Class<PersonData>) Class.forName(PersonData.class.getName());
    Method[] m = ri.getDeclaredMethods();
    for (Method method : m) {
        System.out.println(method);
        if (method.getName().toLowerCase().indexOf(userInp.toLowerCase()) != -1) {
            System.out.println("....method found! -> " + method);
            break;
        }
    }

now consider what could happen if your class has some method like

public String getContentNamespace() {
    return aNamespace;
}

and the user gives name as input....

then maybe you will invoke the wrong method....

Tamas Hegedus · Accepted Answer · 2017-02-20 09:21:41Z

0

Having personName, personAge and personId fields inside a class named PersonData is usually (but not always) bad practice, it's highly redundant and this antipattern even has a name: smurf naming.

But fortunately the question is independent. To get a property value based on partial match you will have to list all property getters and select the one whose name contains the provided string.

answered Feb 20, 2017 at 9:21

Tamas Hegedus

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