jdk1.6 | 易学教程

java.util.concurrent.locks.LockSupport

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【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 要学习JAVA中是如何实现线程间的锁，就得从LockSupport这个类先说起，因为这个类实现了底层的一些方法，各种的锁实现都是这个基础上发展而来的。这个类方法很少，但理解起来需要花费一点时间，因为涉及了很多底层的知识，这些都是我们平时不关心的。上源代码： package java.util.concurrent.locks; import java.util.concurrent.*; import sun.misc.Unsafe; public class LockSupport { private LockSupport() {} // Cannot be instantiated. // Hotspot implementation via intrinsics API private static final Unsafe unsafe = Unsafe.getUnsafe(); private static final long parkBlockerOffset; static { try { parkBlockerOffset = unsafe.objectFieldOffset (java.lang.Thread.class.getDeclaredField("parkBlocker"));

JDK implementation of AbstractList::equals() does not check for list size equality first

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问题 Strangely the default JDK 6 implementation of AbstractList::equals() does not seems to check first if the two lists have the same size : public boolean equals(Object o) { if (o == this) return true; if (!(o instanceof List)) return false; ListIterator<E> e1 = listIterator(); ListIterator e2 = ((List) o).listIterator(); while(e1.hasNext() && e2.hasNext()) { E o1 = e1.next(); Object o2 = e2.next(); if (!(o1==null ? o2==null : o1.equals(o2))) return false; } return !(e1.hasNext() || e2.hasNext()

EclipseLink 2: ANT Task Error

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问题 I got this ANT task: <javac verbose="on" srcdir="${src.dir}" destdir="${build.dir}/${context.path}/classes" debug="${compile.debug}" debuglevel="${javac.debuglevel}" optimize="${compile.optimize}" deprecation="${javac.deprecation}" failonerror="true"> <compilerarg value="-Aeclipselink.persistencexml=${web.dir}/META-INF" compiler="javac1.6" /> <compilerarg line=" -processor org.eclipse.persistence.internal.jpa.modelgen.CanonicalModelProcessor" /> <compilerarg line=" -proc:only" compiler=

Could not detect JDK in the Android Studios installation

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问题 I've tried setting up all the paths what all were suggested by programmers in the following link enter link description here But still i'm getting the error. I've have attached an image regarding this, if anyone faced the same problem and were able to solve them , please do send in the procedure to solve this problem. My Environment Variables are as follows: --------SYSTEM VARIABLES-------------- PATH: C:\Program Files\Java\jdk1.7.0\bin; JDK_HOME:C:\Program Files\Java\jdk1.7.0_79 JAVA_HOME:C:

Deprecate in Java 1.6

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问题 In Java 1.5, to deprecate a method you would: @Deprecated int foo(int bar) { } Compiling this in Java 1.6 results in the following: Syntax error, annotations are only available if source level is 1.5 Any ideas? 回答1: You have to tell the compiler to use 1.6: javac -source 1.6 Or equivalent for your IDE/build system (as others have suggested). 回答2: First, its @Deprecated , and second - double-check if you are really compiling with Java 1.6. What are you using? javac? Eclipse? If using javac,

Deprecate in Java 1.6

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RESTful web service: java.lang.NullPointerException service.AbstractFacade.findAll

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问题 I created a simple XML web service using NetBeans 7's "RESTful Web Services from Database..." wizard. At this point, I want to publish a list of users from the associated mySQL database. When I attempt to access the service via its URL (http://localhost:8080/database/resources/users), I get an error that reads "java.lang.NullPointerException". The stack trace: service.AbstractFacade.findAll(AbstractFacade.java:41) service.UserFacade.findAll(UserFacade.java:51) sun.reflect

Trouble with SSL https connection on port 8443

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问题 We are having trouble with the https (port 8443) connection on an app that runs on Tomcat 7. The app is running fine on http (port 80) now. I have uncommented the "Define a SSL ..." section in the server.xml file and set all the property values (see below). However, when I try to run the app through a browser, I get the error, "The remote device or resource won't accept the connection." Also, when I run a port utility on the server to see what ports are open and listening, it displays port 80

Is it possible to write a program in Java without main() using JDK 1.7 or higher? [duplicate]

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问题 This question already has answers here : Will a static block execute without the main method? (6 answers) Closed last year . The following program will print Hello world when compiled with JDK 1.6 or lower versions of JDK . public class A { static { System.out.println("Hello world"); System.exit(0); } } But JDK 1.7 or higher versions will generate a runtime error as follows when the above program is compiled. Error: Main method not found in class A, please define the main method as: public

How to solve JDK issue unexpected at this time

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问题 I need your assistant in configuring the Jdeveloper 11.1.3 in my machine. I installed it and I installed the JDK. When I tried to ran a sample jsf file " Right Click-> Run", it generates the error: \Java\jdk1.6.0_45 was unexpected at this time. Process Exit I initiated the environment variables as below: Variable Name JAVA_HOME Variable Value "C:\Program Files (x86)\Java\jdk1.6.0_45" So can you please assist in solving the issue. 回答1: Here are some ways to find the short name of a directory.