InvocationTargetException of Java exception Handling (reflection exception)

InvocationTargetException of Java exception Handling (reflection exception)

InvocationTargetException exception by Method.invoke (obj, args ...) Method is thrown. This exception is received when an exception is thrown inside the called method and is not captured!!!

Example:

2. Package com.zzj.test.reflect;
6. Public class Reflect {
8. public void Run (int i) throws zeroexception {
10. b b = new B ();
12. B.run (i);
14. }
16. }
20. Class B {
22. public void Run (int i) throws zeroexception {
24. if (I < 0) {
26. throw New Zeroexception ("parameter cannot be less than 0!  ");
28. }
30. SYSTEM.OUT.PRINTLN ("parameter:" + i);
34. }
36. }
40. Class Zeroexception extends Exception {
42. private Static final long serialversionuid = 1L;
46. private String Detailmessage;
50. Public zeroexception (String detailmessage) {
52. this.detailmessage = detailmessage;
54. }
58. Public String GetMessage () {
60. return detailmessage;
62. }
64. }

Test:

2. Package com.zzj.test.reflect;
6. Import java.lang.reflect.InvocationTargetException;
8. Import Java.lang.reflect.Method;
12. Public class Test {
14. public static void Main (string[] args) {
16. try {
18. Class<?> clazz = Class.forName ("Com.zzj.test.reflect.Reflect");
20. method = Clazz.getmethod ("Run", Int.Class);
22. Method.invoke (Clazz.newinstance (),-1);
24. } catch (ClassNotFoundException e) {
26. E.printstacktrace ();
28. } catch (SecurityException e) {
30. E.printstacktrace ();
32. } catch (Nosuchmethodexception e) {
34. E.printstacktrace ();
36. } catch (IllegalArgumentException e) {
38. E.printstacktrace ();
40. } catch (Illegalaccessexception e) {
42. E.printstacktrace ();
44. } catch (InvocationTargetException e) {
46. System.out.println ("receive exceptions that are not caught inside the called method here");
48. E.printstacktrace ();
50. } catch (Instantiationexception e) {
52. E.printstacktrace ();
54. }
56. }
58. }

Output:

2. The exception that is not caught inside the called method is received here
4. Java.lang.reflect.InvocationTargetException
6. At Sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
8. At Sun.reflect.NativeMethodAccessorImpl.invoke (Unknown Source)
10. At Sun.reflect.DelegatingMethodAccessorImpl.invoke (Unknown Source)
12. At Java.lang.reflect.Method.invoke (Unknown Source)
14. At Com.zzj.test.reflect.Test.main (test.java:11)
16. Caused by:com.zzj.test.reflect.ZeroException: parameter cannot be less than 0!
18. At Com.zzj.test.reflect.b.run (reflect.java:13)
20. At Com.zzj.test.reflect.Reflect.run (reflect.java:6)
22. ... 5 more

You can also print the target exception directly:

2. Package com.zzj.test.reflect;
6. Import java.lang.reflect.InvocationTargetException;
8. Import Java.lang.reflect.Method;
12. Public class Test {
14. public static void Main (string[] args) {
16. try {
18. Class<?> clazz = Class.forName ("Com.zzj.test.reflect.Reflect");
20. method = Clazz.getmethod ("Run", Int.Class);
22. Method.invoke (Clazz.newinstance (),-1);
24. } catch (ClassNotFoundException e) {
26. E.printstacktrace ();
28. } catch (SecurityException e) {
30. E.printstacktrace ();
32. } catch (Nosuchmethodexception e) {
34. E.printstacktrace ();
36. } catch (IllegalArgumentException e) {
38. E.printstacktrace ();
40. } catch (Illegalaccessexception e) {
42. E.printstacktrace ();
44. } catch (InvocationTargetException e) {
46. System.out.println ("receive exceptions that are not caught inside the called method here");
48. Throwable t = e.gettargetexception (); //Get Target exception
50. T.printstacktrace ();
52. } catch (Instantiationexception e) {
54. E.printstacktrace ();
56. }
58. }
60. }

Output:

1. here receives an exception that is not caught inside the called method   
2. com.zzj.test.reflect.zeroexception:  Parameter cannot be less than 0!   
3.     at com.zzj.test.reflect.b.run (Reflect.java:13)   
4.     at com.zzj.test.reflect.reflect.run (Reflect.java:6)    
5.     at sun.reflect.nativemethodaccessorimpl.invoke0 (Native  method)   
6.     at sun.reflect.nativemethodaccessorimpl.invoke ( Unknown source)   
7.     at  Sun.reflect.DelegatingMethodAccessorImpl.invoke (Unknown source)   
8.      at java.lang.reflect.method.invoke (Unknown source)   
9.      at com.zzj.test.reflect.test.main (test.java:11)   

InvocationTargetException of Java Exception Handling (reflection exception)