scjp java 8

HashMap is one of the most commonly used tools in the Java development process, and it is often asked during the interview process, which is analyzed by the author's own understanding and numerous information on the web. The author's local JDK version is a 64-bit 1.8.0_171. The following two articles are recommended for reference: Www.cnblogs.com/little-fly/p/7344285.html Monkeysayhi.github.io/2017/08/26/hashmap Implementation p

JDK or JREThe JRE (Java Runtime) is required to run a Java program. The JDK (Java Development Kit) contains JRE and development tools (such as compilers and debuggers) that are needed to write Java programs, which means that a Java program requires a JDK. 1. Installing

we use the following photos to illustrate the invariance of Java. 1. Declaring a stringString s = "abcd";s stores a reference to a string object. The arrows in the picture below represent this kind of storage reference.2. Assigning a string variable to another string variableString s2 = s;The S2 variable stores the same reference value. So, two variables point to the same string object.3. Merging stringss = s.concat("ef");s now stores a reference to t

is the main method call passed in void introduce (String name, int age) { System.out.println ("Introduce () ..."); System.out.println ("name =" + name); System.out.println ("age =" + age);} return value int Add (int a, int b) { int sum = 0; sum = a + b; return sum return sum;} void Method2 (random ran) { System.out.println ("stochastic:" + ran.nextint ());} Scanner method3 () { return new Scanner (system.in);}}4. TestingPackage Javase.y

constant, which means that the value of the Outsideofimpl after it is declared and initialized cannot be changed.This example simply shows how to use a clear lambda expression instead of an anonymous inner class.One tip: JDK8 's release time has been postponed to February 2014, and a complete release schedule can be found here. I update my lambda build project every day, and if any problems arise in the latest build, please feel free to contact me. I will do my best to build on it, and I will p

are less than 1000, which indicates that n=n+1 is not an atomic level operation. Reason is a simple variable declared as volatile if the current value is related to the previous value of the variable, then the volatile keyword does not work.V. Lock and atomic usage scenariosJDK "The design Atom class is used primarily as a variety of blocks for implementing non-blocking data structures and related infrastructure classes," the document says. the compareandset () method is not a regular replaceme

The demo thread does not consider the full logic. For example, 50 = 20 + 20 + 5 + 5 or 50 = 10 + 10 + 20 + 5... In this example, only the two cases are determined when the value of 50 is changed to zero. The other cases are not considered. Focuses on demonstrating the thread process ....Code: Package cc. nothing2012.blogservlet; Import java. util. arraylist; Import java. util. List; /* = Question:

verification) We understand the role of this module as a facet, telling us that it is a functional module. We can think of it as a facet. To put it bluntly, we write a class. Write a method in this class that deals with the same effect in the core business.We also need to know two keyword:　connection point (Joinpoint), a simple understanding is the method defined in the tangent module. Is the method in the definition class above.　pointcut (Pointcut). Is the collection of connection points, whic

can write this:For example, there are functional interfaces as follows:Package Com.demo.jdk8;public interface Animal {void eat (String food);}　　in the previous Lambda , there was a word for the functional interface1,This can be written in the place where the call is made (LAMDBA expressions):Animal A = food-and {System.out.println (food);}; A.eat ("fish");so write and write a class implementation Animal interface, and then new comes out the same. But this code will be more concise. 2.you can wr

common, and C + +Can be called with the class name, exists in the static zone, has a default valuepublic static final String school_name = "Itcast";Constant capitalization, underlined between wordsAnonymous object: Do the parameters, do the return valueInner classes can use external class membersExternal class to use members of an inner class, you must establish an inner class objectInvoke RuleThe external class name. internal class Name variable = new external Class (). New inner Class ();Vari

database information, but also configures the mapping file so that the mapping file can be imported into the database through the tool class.Tool Class　　This is our own hand-written tool class. Used to map an entity class into a table. and save to the database.Import org.hibernate.cfg.configuration;import org.hibernate.tool.hbm2ddl.schemaexport;/** * Generate DDL for HBM * @author Administrator * */public class Exportdb {public static void main (string[] args) {//default read Hibernate.cfg.xml

Xmind use of Java for development, if there is a memory overflow problem, then must be a desktop shortcut problem, the solution is to directly modify the contents of the shortcut, modified as follows:[Desktop entry]encoding=utf-8Version=1.0Type=ApplicationName=XMind Icon=xmind. PNG Path=/opt/xmind8/xmind_amd64exec=/opt/xmind8/xmind_amd64/xmindstartupnotify= Falsestartupwmclass=Xmindonlyshowin=unity; x-unitygenerated=trueCause Analysis:If you add a s

The double-colon operator is a method reference in Java, and the method references the format of the class Name:: Method name.This is only the method name, and the method name is not followed by the parentheses "()". --------> Such a formula does not necessarily call this method. This is generally used as a lambda expression, and lambda has the so-called lazy load, not parentheses that is, to see how the method is invoked.For example:An expression:Per

The GetAddress method is similar to gethostaddress, where the only difference is that the Gethostaddress method returns an IP address in the form of a string, and the GetAddress method returns an IP address in the form of a byte array. the GetAddress method is defined as follows:Public byte[] GetAddress ()The byte array returned by this method is signed. The value range of byte type in Java is -128?127. If a byte of the returned IP address is an integ

= stream.toArray(String::new);//toArray get Object[], pass it to constructor to get the right type. Use collect the methods and the Collectors many factory methods in the class to get a collection of objects in different containers. listCollect(Collectors.toList()); setCollect(Collectors.Toset()); treesetCollect(Collectors.tocollection(TreeSet::New));//control which type of implementation of CollectionString result = stream.Collect(Collectors.joining()); String result = stream.Collect(