I am trying to get the instance of a generic Field attribute using Java reflection in order to execute a method of this Field.
For instance, If I have a type MyType class with a method getValue() and I have another class MyContainer with an attribute of MyType class, what I am looking for is to get this Field dynamically and execute the getValue() method. Is this possible?
With the following code structure, I am getting:
Exception in thread "main" java.lang.IllegalArgumentException: Can not set test.MyType field test.MyContainer.field1 to test.MyType
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:58)
at sun.reflect.UnsafeObjectFieldAccessorImpl.get(UnsafeObjectFieldAccessorImpl.java:36)
at java.lang.reflect.Field.get(Field.java:393)
at test.Main.main(Main.java:24)
MyContainer
public class MyContainer {
MyType field1;
MyType field2;
public MyContainer() {
super();
}
public MyContainer(MyType field1, MyType field2) {
super();
this.field1 = field1;
this.field2 = field2;
}
public MyType getField1() {
return field1;
}
public MyType getField2() {
return field2;
}
}
MyType
public class MyType {
private MyEnum var1;
private String var2;
public MyType() {
super();
}
public MyType(MyEnum var1, String var2) {
this.var1 = var1;
this.var2 = var2;
}
public MyEnum getVar1() {
return var1;
}
public String getVar2() {
return var2;
}
}
MyEnum
public enum MyEnum {
A(""),
N("0");
private final String value;
private MyEnum(String value) {
this.value = value;
}
@Override
public String toString() {
return this.value;
}
}
Execution
java.lang.reflect.Field[] allFields = MyContainer.class.getDeclaredFields();
MyType obj = new MyType();
for (java.lang.reflect.Field field : allFields) {
if ( MyType.class == field.getType() ){
field.setAccessible(true);
MyType myAux = (MyType) field.get(obj);
String dowhatever = myAux.getVar2();
}
}
As you could see in the exception, test.MyType field type seems to be totally equivalent to test.MyType provided in the casting. What I am doing wrong?
