java.lang.IllegalArgumentException：对象不是声明类的实例
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java.lang.IllegalArgumentException: object is not an instance of declaring class
提问by svager
I am trying to figure out how to use reflection. I have set up 2 classes one has basic validation for numbers
我想弄清楚如何使用反射。我已经设置了 2 个类，其中一个对数字进行了基本验证
public class Reflectee {
String str;
public Reflectee(String str){
this.str=str;
}
public Reflectee(){
}
public boolean doSomething(String str){
boolean flag=true;
try{
Integer.parseInt(str);
}catch (NumberFormatException e){
flag=false;
}
return flag;
}
}
and then I have created a class that is going to use reflection to invoke doSomething method.
然后我创建了一个类，该类将使用反射来调用 doSomething 方法。
public class Reflector {
private String str="22";
public boolean reflect(){
Reflectee r=new Reflectee();
Class clazz=r.getClass();
boolean b=false;
try {
Method m=clazz.getDeclaredMethod("doSomething",String.class);
b=(Boolean)m.invoke(this,str); //Exception is here
} catch (NoSuchMethodException | SecurityException |
IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return b;
}
}
I get an exception when I am trying to invoke a method the exception is
当我尝试调用异常的方法时出现异常
java.lang.IllegalArgumentException: object is not an instance of declaring class
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 com.app.example2.Reflector.reflect(Reflector.java:16)
at com.app.example2.test.Reflector_UT.test(Reflector_UT.java:16)
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 org.junit.runners.model.FrameworkMethod.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
at org.junit.runners.ParentRunner.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner.schedule(ParentRunner.java:63)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access b=(Boolean)m.invoke(this,str); //Exception is here
0(ParentRunner.java:53)
at org.junit.runners.ParentRunner.evaluate(ParentRunner.java:229)
at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
I am sure that I am missing something minor. Any ideas what is wrong?
我确定我错过了一些小事。任何想法有什么问题？
Thanks
谢谢
采纳答案by Arun
problem is on the following line
问题在下一行
b=(Boolean)m.invoke(r,str); //Exception is here
you have to invoke method on the Reflectee object rather than this(Reflector object)
你必须在 Reflectee 对象上调用方法而不是 this(Reflector object)
##代码##