Java Programming/Reflection/Dynamic Invocation

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Navigate Reflection topic:

We start with basic transfer object:


Computer code
package com.test;

public class DummyTo {
    private String name;
    private String address;
   
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public DummyTo(String name, String address) {
        this.name = name;
        this.address = address;
    }

    public DummyTo() {
        this.name = new String();
        this.address = new String();
    }

    public String toString(String appendBefore)
    {
        return appendBefore+" "+name+" , "+address;
    }
}


Following is the example for invoking method from the above mentioned to dynamically. Code is self explanatory.


Computer code
package com.test;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class ReflectTest {
    public static void main(String[] args)
    {
        try {
            Class dummyClass = Class.forName("com.test.DummyTo");
           
            //parameter types for methods
            Class[] partypes = new Class[]{String.class};
           
            //Create method object . methodname and parameter types
            Method meth = dummyClass.getMethod("toString", partypes);
           
            //parameter types for constructor
            Class[] constrpartypes = new Class[]{String.class, String.class};
           
            //Create constructor object . parameter types
            Constructor constr = dummyClass.getConstructor(constrpartypes);
           
            //create instance
            Object dummyto = constr.newInstance(new String[]{"Java Programmer", "India"});
       
            //Arguments to be passed into method
            Object[] arglist = new Object[]{"I am"};
       
            //invoke method!!
            String output = (String) meth.invoke(dummyto, arglist);
            System.out.println(output);
       
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SecurityException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }
}


Conclusion: Above examples demonstrate the invocation of method dynamically using reflection.

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