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最新文章列表
[Ljava.lang.Object; cannot be cast to [Ljava.lang.Long
问题描述
今天在进行Java集合类转换为数组对象的时候报如下错误:
java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.Long;
自己代码如下:
import java.util.HashMap;
import java.util.Map;
pub ...
Item 29: Consider typesafe heterogeneous containers
1. Generic containers limit you to a fixed number of type parameters per container. In some cases we may parameterize the key instead of the container. Then present the parameterized key to the conta ...
Item 26: Favor generic types
1. Generic types are safer and easier to use than types that require casts in client code. When you design new types, make sure that they can be used without such casts. This will often mean making t ...
Item 25: Prefer lists to arrays
1. Arrays are covariant which means simply that if Sub is a subtype of Super, then the array type Sub[] is a subtype of Super[]. Generics, by contrast, are invariant: for any two distinct types Type1 ...
Item 24: Eliminate unchecked warnings
1. When you program with generics, you will see many compiler warnings: unchecked cast warnings, unchecked method invocation warnings, unchecked generic array creation warnings, and unchecked conver ...
Item 23: Don’t use raw types in new code
1. Raw types behave as if all of the generic type information were erased from the type declaration. For all practical purposes, the raw type List behaves the same way as the interface type List did ...
画图板中重绘功能遇到的问题
画图板的功能还在日趋完善,现在正在努力实现利用自定义队列存储绘图信息然后重绘的功能,在实现这个功能的过程中,遇到的最多的异常就是java.lang.ClassCastException了,
造成这个异常的原因就是重绘时读取存储的信息时出现了错误,导致一些类赋值时不匹配。
就拿直线来说,我们要保存直线的信息,需要在每次画完直线时存储这条直线的信息,即在鼠标释放(MouseReleased)里面 ...
json-lib net.sf.ezmorph.bean.MorphDynaBean cannot be cast to xxx
在使用json-lib 反序列化时,报错:
Exception in thread "main" java.lang.ClassCastException: net.sf.ezmorph.bean.MorphDynaBean cannot be cast to com.jn.json.bean.Student
at com.jn.test.Test2.test_reseri ...
用Proxy 的静态方法 newProxyInstance 创建代理
示例代码:
TestInterface s = (TestInterface)Proxy.newProxyInstance(TestProxy.class.getClassLoader(), new Class[]{TestInterface.class}, new InvocationHandler() {
@Override
public Object invoke(Ob ...
jboss运行时报:ClassCastException
今天在用jboss服务的时候,从web模块访问ejb模块时,在创建ejb的时候,报下面的额错误
Caused by: java.lang.ClassCastException: $Proxy209 cannot be cast to org.omg.CORBA.Object
at com.sun.corba.se.impl.javax.rmi.PortableRemoteObject.narrow( ...
ClassCastException
ClassCastException是JVM在检测到两个类型间转换不兼容时引发的运行时异常。此类错误通常会终止用户请求。在执行任何子系统的应用程序代码时都有可能发生ClassCastException异常。通过转换,可以指示Java编译器将给定类型的变量作为另一种变量来处理。对基础类型和用户定义类型都可以转换。Java语言规范定义了允许的转换,其中大多数可在编译时进行验证。不过, ...
Cassandra重启报错 java.lang.ClassCastException
通过CQL创建了若干表格,比如:
CREATE TABLE fileindex(
recid varchar,
agentno varchar,
customerno varchar,
recfile varchar,
createtime varchar,
PRIMARY KEY(recid)
);
CREATE INDEX ON fileindex(agentno);
C ...
java.lang.ClassCastException
java.lang.ClassCastException:com.th.ly.ThProvider
at com.th.ly.BaseProperties.deltes(BaseProperties.java:253);
类型转换错误
例如我有一个方法(getA())返回一个对象A,而你却把他造型为B对象,于是就产生这样的错误了。
if(o instanceof A) {
ids.add(( ...
struts2 上传下载模板
第一 struts2 更新比较慢。核心的xwork 基本不变。
第二 给自己写了个struts2 的上传下载模版,免得以后经常写,写又忘记,又要上网去查询。单文件上传跟多文件上传代码差不多,这里模版里面是单文件上传
第三错误解决
struts2下载文件时出错提示:java.lang.ClassCastException: java.io.ByteArrayInputStream
这是配置文件里面 ...