java basic interview questions

After JDK5, Java provides a more convenient security mechanism that uses lock locks for thread-locked operations and release operations without using synchronized . More clear. Example:Lock lock=new Reentrantlock ();Lock.lockCode that needs to be lockedLock.unlockWhy is lock more secure? Because synchronized may cause deadlock phenomenon, specifically about the deadlock phenomenon can refer to the operating system, there is no more to say.Summarize th

client. The expression is defined between the two tags, 9. What does the implied object mean? What are the hidden objects?JSP implied objects are some Java objects in the page, and the JSP container allows these Java objects to be used by developers. Developers can use them directly without a clear statement. JSP implicit objects are also called predefined variables. The following lists the implied objects

Java Exception Common interview question one, Java exception understandingExceptions are mainly handling errors that cannot be caught at compile time. The problem can continue to execute smoothly, without causing the program to terminate, to ensure the robustness of the program.Processing: When an abnormal state is generated, if the current context does not have

First, let's talk about the differences between final, finally, and finalize.　　Second, can anonymous inner class (anonymous internal class) be extends (inherited) other classes, or implements (implemented) interface (Interface )?　　Third, the difference between static nested class and inner class is that the more you say, the better (the more general the interview questions are ).　　Fourth, the difference bet

115 Java Interview Questions and answers-ultimate list (I), 115 java Object-Oriented Programming (OOP) Java is a computer programming language that supports concurrency, class-based, and object-oriented. The advantages of object-oriented software development are listed bel

Java Architects interview questions, how to become architectsOften interview some candidates, sorted out my interview using the topic, LU continued to organize a lot of problems, so each time to draw a part to ask. The answer will be gradually released in later articles.

file names or directories under the current path for more informationpwd--Show current path locationcd--Switching directoriesPing IP address--test network connection is unblockedVim file name--Modify filei--into edit stateesc--exiting a previous state: wq--Save Exit: Q!—— indicates forced exit is not recommended for useCP Original file name copy file name--copy fileMV A.txt b.txt--renamed A.txt to B.txtMV A.txt aa/--move a.txt to the AA folderclear--Clear Screen CommandService iptables stop--sh

Test your Java basic test questions: This is a few interview questions I designed. The requirement is that there should be as few questions as possible and they can be completed within five minutes, but it can basically reflect th

; k ) TestFunction (k, J, i);On the basis of scenario one, this scheme puts the instantiation of the cyclic variables out of the loop, which can further reduce the number of instances of the related cyclic variables, and the scheme time-consuming situation is as follows: Variable Instantiation (number of times) Initialization (number of times) Comparison (number of times) Self-increment (number of times) I 1 1 10 1

Java custom generic interview questions: receive any array to reverse, java custom You can only operate on a certain type for reversal without using the generic type. The Code is as follows: package com.swift.fanxing;import org.junit.Test;public class RenyiReverse { @Test public void test() { int arr[]=new

article to learn more about the callable,future example.6. What is Futuretask?Futuretask is a fundamental implementation of the future, and we can use it with executors to handle asynchronous tasks. Usually we do not need to use the Futuretask class, it becomes very useful when we intend to rewrite some methods of the future interface and keep the original base implementation. We can just inherit from it and rewrite the methods we need. Read the Java

COSCO Java interview question zzz COSCO Java interview questions Java training materialsI. Java language1. Three basic features of object-or

choose an array instead of a ArrayList. If we want to traverse a map in order of insertion, we need to use TreeMap. If we don't want to repeat, we should use set.(2) Some collection classes allow you to specify the initial capacity, so if we can estimate the number of stored elements, we could use it to avoid re-hashing or resizing.(3) programming based on interfaces, rather than implementation-based programming, allows us to easily change the implementation later.(4) Always use type-safe gener

type as needed. For example, if you specify a size, we will choose an array instead of a ArrayList. If we want to traverse a map in order of insertion, we need to use TreeMap. If we don't want to repeat, we should use set.(2) Some collection classes allow you to specify the initial capacity, so if we can estimate the number of stored elements, we could use it to avoid re-hashing or resizing.(3) programming based on interfaces, rather than implementation-based programming, allows us to easily ch

corresponding action, while the user's data to fill the corresponding actionform, and then the Actionform is distributed to action for processing.3.Action automatically calls the Excute method, in which the action takes the user-filled data from the Actionform and invokes the model (JavaBean) for processing, and then displays the results of the processing in a different view (JSP page)struts-config.xml:struts 's configuration file .It says that each user's request is handled and forwarded throu

Java, which meansThird-party applications developed by the SDK must use the Java language. However, this is not equivalent to "third-party applications can onlyUse Java ". At the first release of the Android SDK, Google claimed that its virtual machine Dalvik supported JNI programming.Method, that is, third-party applications can call their own C dynamic library

　 The Java Collection Framework is the most frequently asked question of Java interviewing, and it is necessary to understand the powerful features of Java technology to master the set framework. Here are some practical questions, often asked in the core Java

. } } 56. Problem: Give an integer variable A, write two pieces of code, the first set of a bit3 is 1, the other bit does not change, how to implement it? /** * @author sanchan * @since 1.0 */ publicclassTest{ publicstaticvoidmain(String[]args){ //给一整型变量a，写两段代码，第一个设置a的bit3 为1，其他bit不变，怎么实现呢？ inta=8; //打印二进制 System.out.println(Integer.toBinaryString(a));//输出 1000 System.out.println(Integer.toBinaryString(a|4));//输出 1100 }

) Select the correct collection type as needed. For example, if you specify a size, we will choose an array instead of a ArrayList. If we want to traverse a map in order of insertion, we need to use TreeMap. If we don't want to repeat, we should use set.(2) Some collection classes allow you to specify the initial capacity, so if we can estimate the number of stored elements, we could use it to avoid re-hashing or resizing.(3) programming based on interfaces, rather than implementation-based prog

TreeMap. If we don't want to repeat, we should use set.(2) Some collection classes allow you to specify the initial capacity, so if we can estimate the number of stored elements, we could use it to avoid re-hashing or resizing.(3) programming based on interfaces, rather than implementation-based programming, allows us to easily change the implementation later.(4) Always use type-safe generics to avoid classcastexception at run time.(5) Using the immutable classes provided by the JDK as key to t