For example, you have am arrayPrint method, which takes a String[] as its argument, in the Invoked class.
public class Invoked {
public void arrayPrint(String[] items) {
int i = 1;
for (String item : items) {
System.out.println("Item "+ i ++ ": " + item);
}
}
}
Now, you want to call this arrayPrint method via reflection in the Invoker class.
public class Invoker {
public static void main(String[] args) {
String[] items = new String[3];
items[0] = "Hello Dear!";
items[1] = "So glad to see you.";
items[2] = "How have you been?"
Class invokedClass = Class.forName("Invoked");
Method printMethod = invokedClass.getMethod("arrayPrint", String[].class);
//This line will throw an Exception
printMethod.invoke(new Invoked(), items);
}
}
When it is executed, it throws the below exception.
Exception in thread "main" java.lang.IllegalArgumentException: wrong number of arguments
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at test.Invoker.main(Invoker.java:29)
This exception occurs because the invoke method takes each element in the items array as a separate argument, therefore, in this case, there are three arguments in total. But the arrayPrint method only takes one argument.
To fix it:
Change the line above that gives the exception to this:
printMethod.invoke(new Invoked(), new Object[] {items});
public class Invoked {
public void arrayPrint(String[] items) {
int i = 1;
for (String item : items) {
System.out.println("Item "+ i ++ ": " + item);
}
}
}
Now, you want to call this arrayPrint method via reflection in the Invoker class.
public class Invoker {
public static void main(String[] args) {
String[] items = new String[3];
items[0] = "Hello Dear!";
items[1] = "So glad to see you.";
items[2] = "How have you been?"
Class invokedClass = Class.forName("Invoked");
Method printMethod = invokedClass.getMethod("arrayPrint", String[].class);
//This line will throw an Exception
printMethod.invoke(new Invoked(), items);
}
}
When it is executed, it throws the below exception.
Exception in thread "main" java.lang.IllegalArgumentException: wrong number of arguments
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at test.Invoker.main(Invoker.java:29)
This exception occurs because the invoke method takes each element in the items array as a separate argument, therefore, in this case, there are three arguments in total. But the arrayPrint method only takes one argument.
To fix it:
Change the line above that gives the exception to this:
printMethod.invoke(new Invoked(), new Object[] {items});
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