We start with basic transfer object:
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Code listing 10.1: DummyTo.java
1 package com.test;
2
3 public class DummyTo {
4 private String name;
5 private String address;
6
7 public String getName() {
8 return name;
9 }
10
11 public void setName(String name) {
12 this.name = name;
13 }
14
15 public String getAddress() {
16 return address;
17 }
18
19 public void setAddress(String address) {
20 this.address = address;
21 }
22
23 public DummyTo(String name, String address) {
24 this.name = name;
25 this.address = address;
26 }
27
28 public DummyTo() {
29 this.name = new String();
30 this.address = new String();
31 }
32
33 public String toString(String appendBefore) {
34 return appendBefore + " " + name + ", " + address;
35 }
36 }
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Following is the example for invoking method from the above mentioned to dynamically. Code is self explanatory.
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Code listing 10.2: ReflectTest.java
1 package com.test;
2
3 import java.lang.reflect.Constructor;
4 import java.lang.reflect.InvocationTargetException;
5 import java.lang.reflect.Method;
6
7 public class ReflectTest {
8 public static void main(String[] args) {
9 try {
10 Class<?> dummyClass = Class.forName("com.test.DummyTo");
11
12 // parameter types for methods
13 Class<?>[] partypes = new Class[]{String.class};
14
15 // Create method object. methodname and parameter types
16 Method meth = dummyClass.getMethod("toString", partypes);
17
18 // parameter types for constructor
19 Class<?>[] constrpartypes = new Class[]{String.class, String.class};
20
21 //Create constructor object. parameter types
22 Constructor<?> constr = dummyClass.getConstructor(constrpartypes);
23
24 // create instance
25 Object dummyto = constr.newInstance(new Object[]{"Java Programmer", "India"});
26
27 // Arguments to be passed into method
28 Object[] arglist = new Object[]{"I am"};
29
30 // invoke method!!
31 String output = (String) meth.invoke(dummyto, arglist);
32 System.out.println(output);
33
34 } catch (ClassNotFoundException e) {
35 e.printStackTrace();
36 } catch (SecurityException e) {
37 e.printStackTrace();
38 } catch (NoSuchMethodException e) {
39 e.printStackTrace();
40 } catch (IllegalArgumentException e) {
41 e.printStackTrace();
42 } catch (IllegalAccessException e) {
43 e.printStackTrace();
44 } catch (InvocationTargetException e) {
45 e.printStackTrace();
46 } catch (InstantiationException e) {
47 e.printStackTrace();
48 }
49 }
50 }
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Console for Code listing 10.2
I am Java Programmer, India
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Conclusion: Above examples demonstrate the invocation of method dynamically using reflection.
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To do:
Add some exercises like the ones in Variables
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