java 8 certification questions

JAVA engineer interview questionsZookeeper I went to a company for an interview today. I felt dizzy with my brains. I didn't make a few algorithm questions. The questions were relatively simple. I should have prepared myself, but the status was not good, after the interview, I felt quite dissatisfied. I still had to wait for a while and make sufficient preparatio

ImportNew Note: This article is one of the Java interview series compiled by ImportNew. You can view all the Java interview series from here. The common Interview Questions introduced in this article are about the overloading method and overriding method. Q.What is the output result of the following code snippet?View Code 1 public class MethodOverrideVsOverload

Java interview questions: how to sort HashMap key values In Java, HashMap is a data structure used to store "key" and "value" Information pairs. Unlike Array, ArrayList, and lists, it does not maintain the order of inserted elements.Therefore, sorting HashMap Based on keys or values is a very difficult interview question if you do not know how to solve it. Next

: hibernate always uses the locking mechanism of the database, never locking objects in memory! Just specify the isolation level for the JDBC connection, and then let the database take care of everything.class Lockmode defines the different locking levels required for hibernateLockmode.upgrade,lockmode.upgrade_nowait,lockmode.read;hibernate refused connection, server crashes cause1. DB does not open 2. There may be a problem with the network connection 3. The connection configuration is 4 wrong.

the JspWriter class and is an object commonly used to output content to the clientPage object:Points to the current JSP page itself, a bit like the this pointer in the class, which is an instance of the Java.lang.Object classApplication object:The Application object implements the sharing of data among users and can store global variables. It starts at the start of the server until the server shuts down, during which time this object will persist, so that in the connection between the user's fr

are differences between these two triggers. What is the difference between statement-level triggering and row-level triggering. The trigger runs before the trigger event occurs, and the trigger runs after the trigger event. The trigger can obtain the new field values before the event. A statement-Level Trigger can be executed before or after the statement is executed, and a row-Level Trigger is triggered once for each row affected by the trigger. COSCO interview

are characterized by the inability to define variables, and all methods are abstract methods . abstract classes can have variables and do not enforce the need for abstract methods .Inheritance of class 16 and implementation of interfacesParsing: Class Inheriting the parent class implements the interface with the class, which is essentially the same. is to either extend or rewrite the parent class or interface as a template on this template. In practical programming, programmers often need to in

1.Volatile and synchronized different points(1), volatile can only be used for variables, the use of a small range. Synchronized can be used in variables, methods, classes, synchronous code blocks, etc., the scope of use is relatively wide.(2), volatile can only guarantee visibility and order, can not guarantee atomicity. The visibility, order and atomicity of synchronized can be certified.(3), volatile does not cause thread blocking. Synchronized may cause thread blocking.Atomicity, visibility,

private.3. Is String the most basic data type?No. There are only 8 basic data types in Java: Byte, short, int, long, float, double, char, Boolean, except for the base type (primitive type) and the enumeration type (enumeration type). All that is left is the reference type (reference type).4. Explain the usage of the in-memory stack (stack), heap, and static storage.Usually we define a variable of a basic d

In the Java language, the following questions about character set encoding (Character set encoding) and internationalization (i18n), which are correct?A. Each Chinese character occupies 2 bytes, and each English character occupies 1 bytesB. Assuming that the characters in the database are GBK encoded, the Web page that displays the database data must also be GBK encoded.The char type of C.java, which usuall

Java multithreading interview questions Induction1. What are the implementation methods for multithreading? The following example shows the thread synchronization. (1) Java multithreading has two implementation methods: Inheriting the Thread class and implementing the Runnable interface. Thread implements the Runnable interface. Two simple thread examples: Packa

Think about it, I have interviewed two or three times in this period, met some questions, had a written test, and had a verbal test. While there was still an impression, and had a computer power, I wrote down what I remember first ~~ Basically, they are all about Java. 1. Understanding of object-oriented 2. Three major features of Java 3. I had no idea about

VariantTest{ public static int staticVal = 0; public int instanceVal = 0; public VariantTest(){ staticVal++; instanceVal++; System.out.println("staticVal="+staticVal+",instanceVal="+instanceVal); }}13. Is it possible to make a call to a non-static method from within a static method?No. Because the non-static method is to be used in conjunction with a class object, you must create an object before you can make a call to the method on that object, and the static m

by one, and a key is the corresponding value. But sometimes we need a reverse query, such as a value to find its key, this data structure is called bidirectional map, unfortunately the JDK does not support it.Apache and guava together provide this bidirectional map implementation, which in its implementation specifies that both the key and the value must be a 1:1 relationship.7, copy of the mapJava provides many ways to replicate a map, but those methods do not always synchronize. Simply put, t

in the same class. 7, The following overload description error is (B) a) method overloads can only occur within a class of the internal B) Construction method cannot overload C) overloads require the same method name, with a different argument list d) method return value type is not a condition that distinguishes method overloads 8, A) Abstract class No construction method B) Abstract class must provide an abstract method C) A cl

Analysis and Summary of Baidu Java R D interview questions 1. Analysis of Common application scenarios in singleton mode. Among the 23 design modes, the singleton mode is the largest. It is easy to understand, but applicable to scenarios. Are you really familiar with this? The use of Singleton is because there is no need to create an object for each request, which wastes both CPU and memory. The use of mu

Java's current heat has declined, but there are still a lot of people who learn java. Java's post is also a lot of infiltration. So, those classic Java knowledge points, you can see the problem can say 123? Come and have a look.The difference between 1.JDK and JRE What is the difference between 2.final, finally, and finalize?3. The difference between threads and processesHow does the HashMap in 4.

"); Class.forName ("Memoryanalyse"); }The Class.forName (class name string) is the manual loading of the class to the method area, resulting in aI=0 Constructor Code k=0 n=0 j=0I=1 T1 k=1 n=1 j=0I=2 Constructor Code k=2 n=2 j=0I=3 T2 k=3 n=3 j=0i=4 I k=4 n=4 j=0I=5 J k=5 N=5 j=0I=6 Static code k=6 n=99 j=6 //This line occurs because the static snippet is executed when the class loads. n=99 is because the class is loaded, and the initial value of n is 99 .Then change to our previous d

. We can use this property to set the print report to another report, and the only difference to display the report is that the chart is a static picture. This can not only ensure that the dynamic effect of the statistical chart on the page, but also to ensure that the chart can be printed correctly.6. Sheet Report Group Implementation method:Detailed reference: http://blog.csdn.net/knowledgewang/article/details/63651157. Garbled problem:For details, please refer to the "Quick escape garbled" do

Consistent, value is UTF-82) browser display character encoding consistent with the requested JSP page encoding2. get The Chinese parameter value in the JSP page: the encoding used by the default parameter in transit is iso-8859-11) for post requests: call request.setcharacterencoding ("UTF-8") before getting the parameters;1 2 request.setcharacterencoding ("UTF-8");3 4 %>5Username=Request.getpara