java scjp questions and answers

threadlocal, Blocking Queue, counting semaphore and concurrenthashmap are more prevalent. 15 Java Multi-threaded face questions and answers 1 Now there are T1, T2, T3 three threads, how do you ensure that T2 after T1 execution, T3 after the implementation of T2 execution? This threading problem is usually asked in the first round or during the phone interview

is used for medium-sized and large-scale data applications. The serial collector is sufficient for most small applications, which require about 100M of memory on modern processors.41. In Java, when can objects be garbage collected?This object can be recycled when the object becomes inaccessible to applications that currently use the object.Is there a garbage collection in the permanent generation of 42.JVM?Garbage collection does not occur in a perma

The Java Collection framework is the foundation of the Java programming language and is an important knowledge point in the Java interview. Here, I've listed some important questions and answers about the Java collection.What is a

applications. The serial collector is sufficient for most small applications, which require about 100M of memory on modern processors.41. In Java, when can objects be garbage collected?This object can be recycled when the object becomes inaccessible to applications that currently use the object.Is there a garbage collection in the permanent generation of 42.JVM?Garbage collection does not occur in a permanent generation, and if it is permanently full

applications. The serial collector is sufficient for most small applications, which require about 100M of memory on modern processors.41. In Java, when can objects be garbage collected?This object can be recycled when the object becomes inaccessible to applications that currently use the object.Is there a garbage collection in the permanent generation of 42.JVM?Garbage collection does not occur in a permanent generation, and if it is permanently full

foundation, grasp the principle of good technology, and then to practice, so as to understand a technology, learning can not have!In addition, the interview process, to maintain self-confidence, will not be bold to say no, no good disgrace, not to say you really will not, perhaps forget, perhaps did not notice, remember the interview topic, back to their own supplementary information and related information, I believe you will be more and more calmly, to remember not for the interview and inter

foundation, grasp the principle of good technology, and then to practice, so as to understand a technology, learning can not have!In addition, the interview process, to maintain self-confidence, will not be bold to say no, no good disgrace, not to say you really will not, perhaps forget, perhaps did not notice, remember the interview topic, back to their own supplementary information and related information, I believe you will be more and more calmly, to remember not for the interview and inter

thread encounters IO blocking, I do not think there is a way to abort the thread. If the thread is blocking because of a call to wait, sleep, or join methods, you can break the threads and wake it up by throwing interruptedexception. I've written earlier how to deal with blocking methods in Java has a lot of information about handling thread blocking.13) What is the difference between Cyclibarriar and Countdownlatch in

load Java extension libraries. The implementation of the Java virtual machine provides an extension library directory. The class loader finds and loads Java classes in this directory.3. Systems Class Loader (System class loader): It loads Java classes based on the Java appl

having to consider which instance of the subclass is returned.Proxy Mode: provides a proxy object for an object and controls the reference of the original object by the proxy object. In actual development, according to the different purposes, the agent can be divided into: Remote agent, virtual agent, protection agent, cache agent, firewall agent, synchronous agent, intelligent reference Agent.Adapter Mode: transforms the interface of a class into another interface that the client expects, so t

method in a subclass that has the same name and parameters as its parent, we say that the method is overridden (override). When an object of a subclass uses this method, the definition in the subclass is called, and for it the definition in the parent class is "masked". If more than one method with the same name is defined in a class, they either have a different number of arguments or have different parameter types, which is called a method overload (overload).The overloaded method is a ty

problem is if the elements in the collection, this will bring some errors, some unpredictable errors, So it is forbidden to do so in collection.29th, when an object is passed as a parameter to a method, this method can change the properties of the object and return the changed result, so is this a value pass or a reference pass?Reference passing, there is no doubt that object passing can only be a reference. You can change the content of the reference, but not change the reference itself.30th,