classcastexception

问题 I have a method which has a list of inputs and each input value I have to cast it to required type. (Actually this list has values of parameters in "some" form which I am supposed to converted into required type, the required type is the type which method requires, this is for api invocation through reflection) I have written code like this: Type[] argTypes = method.getGenericParameterTypes(); List<Object> acutalValues = // List of actual values from method input. // Resultant list of

问题 I have a number (power(2,k)) of BitSet objects and I want to store them in a SortedSet . I use the code: Set <BitSet> S= new TreeSet<>(); However, I am getting this error: java.lang.ClassCastException: java.util.BitSet cannot be cast to java.lang.Comparable How do I implement comparable interface? Or is there any other way to sort these elements of type BitSet ? 回答1: There are two ways to use a TreeSet . Have it contain objects that implement Comparable Have a custom Comparator object that

问题 Please help me to convert ArrayList to String[]. The ArrayList contains values of type Object(VO). For example, The problem is that I need to convert a country List to String Array, sort it and then put it in a list. However I am getting a ClassCastException. 回答1: String [] countriesArray = countryList.toArray(new String[countryList.size()]); I have assumed that your country List name is countryList . So to convert ArrayList of any class into array use following code. Convert T into the class

问题 I'm using a Double variable which holds the Item price. That variable is stored in postgresql database under a column of money type. I use setBigDecimal(position,value) SQL function.In other part, i'm using a JSpinner as input. Double current = 0.0; Double min = (double) Integer.MIN_VALUE; Double max = (double) Integer.MAX_VALUE; Double step = 0.1; JSpinner priceSpinner = new JSpinner(new SpinnerNumberModel(current, min, max, step)); When the user clicks on a button, I get the value entred by

问题 I want to upload an image using a groovy on grails. My gsp page is as follows (I am showing a simplified version of the original) <g:form controller="post" action="save" enctype="multipart/form-data"> My picture <input type="file" name="myPicture" /> <g:submitButton name="submit" value="Save"/> </g:form> My domain class is as follows: class Post { byte[] myPicture static mapping = { myPicture type: "blob" } I need this mapping otherwise MySql will create a smallblob which is to small to fit

问题 Here is some sample code...I always seem to get a ClassCastException...anybody point out what I am doing wrong? package com.query; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.Map; import java.util.Set; import java.util.TreeSet; import org.junit.Test; import com.google.common.collect.Sets; public class ClassCastExceptionTest { @Test public void test() { A<SomeType> a1 = new A<SomeType>(1); A<SomeType> a2 = new A<SomeType>(2); A<SomeType>

问题 I'm using java generics and varargs. If I use the following code, I'll get a ClassCastException , even though I'm not using casts at all. Stranger yet, if I run this on Android (dalvik) no stack trace is included with the exception, and if I change the interface to abstract class, the exception variable e is empty. The code: public class GenericsTest { public class Task<T> { public void doStuff(T param, Callback<T> callback) { // This gets called, param is String "importantStuff" // Working

问题 i have a simple activity program in android. basically the class just extends Activity. But when i start it i get a ClassCastException in the constructor of my class. i dont even have a constructor defined, so it must be in the constructor of the superclass which is Activity. unfortunately the debugger doesnt give any detailed information on what class it is trying to cast. here is the stacktrace: Thread [<1> main] (Suspended (exception RuntimeException)) ActivityThread$PackageInfo

问题 Studying for my OCA Java SE 7 Programmer I exam, so newbie question. I have an example question I do not understand. The following code compiles, but gives a ClassCastException at runtime: interface Roamable { } class Phone { } public class Tablet extends Phone implements Roamable { public static void main(String... args) { Roamable var = (Roamable) new Phone(); } } When I change Roamable var = (Roamable) new Phone(); into Roamable var = (Roamable) new String(); I get a compilation error

问题 I have been trying to do a little project that needs an appendable ObjectOutputStream. I have gone through a couple of solutions and i found this It seemed to solve my problem at first. But on further development of my project i started getting unexpected exceptions. The following are my classes. public class PPAccount implements Serializable { private Profile profile; private String email; private float accountBal; private boolean isActivated; private String activationCode; private ArrayList