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;
}
}
然后我创建了一个将使用反射来调用doSomething方法的类。
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;
}
}
当我尝试调用异常
的方法时,我得到一个异常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$1.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$3.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
at org.junit.runners.ParentRunner$2.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)
我确信我错过了一些小事。有什么想法是错的吗?
由于
答案 0 :(得分:4)
问题出现在以下一行
b=(Boolean)m.invoke(this,str); //Exception is here
你必须在Reflectee对象而不是this(Reflector对象)
上调用方法 b=(Boolean)m.invoke(r,str); //Exception is here