java 8 certification questions

COSCO Java interview question zzz COSCO Java interview questions Java training materialsI. Java language1. Three basic features of object-oriented2. Concepts and differences between method overloading and method Rewriting3. Features of interfaces, internal classes, and abstr

simply use an index instead of creating an iterator object. Linklist also creates objects for each inserted element, all of which you have to understand that it also brings additional overhead.Finally, in the book Practical Java, Peter Haggar suggests using a simple array instead of a vector or ArrayList. This is especially true for programs with high efficiency requirements. Because the use of arrays (array) avoids synchronization, additional method

types of streams are there in 5.java? The JDK provides some abstract classes for inheritance for each type of stream, tell me what classes they are. The stream provided by the JDK inherits four classes:InputStream (byte input stream), OutputStream (byte output stream), Reader (character input stream), Writer (character output stream).Sort by Flow:Input stream: The stream from which the program can read data.Output stream: The stream to which the prog

, preserving the folder structure. That is, you should have the following folder structure:Sun--Security--ActionSun-To-JDBC5. Open a CMD window. Go to the parent folder of the Sun folder. Run command: JAR-CVF Jdbc.jar Sun6. The above command will create a file named Jdbc.jar7. Copy the Jdbc.jar to your JDK8 or JRE8 lib folder. If this doesn't work, try using the Lib\ext folder.8. Copy Jdbcodbc.dll from JRE \ Bin installed on JRE 7 to the JRE \ Bin ins

not call the constructor of the parent class (The constructor of a subclass can implicitly invoke the parameterless constructor of the parent class）C. Subclasses must invoke the constructor of the parent class through the super () keywordD. Subclasses cannot inherit the constructor of the parent class.(IBID.)14. In the following statements, it is correct that: (A)A. Class is a collection of variables and methodsB. An array is a collection of unordered data (type can be any data type in

First question:1 /*2 See program Write results:3 A: The principle of accessing member variables: the nearest principle. 4 questions about B:this and super:5 this accesses members of this class6 Super access to the members of the parent class (as you can understand)7 C: The default constructor method for the parent class is executed before all the constructor methods of the subclass are executed. 8 D: Initia

instability or even crashes, The GC mechanism provided by Java can automatically monitor whether an object exceeds the scope to achieve the purpose of automatically reclaiming memory, and the Java language does not provide an explicit way to dispose of the allocated memory.20. Write a singleton mode (Singleton)//第一种 ：饿汉模式public class SingleTon{ private SingleTon(){} //实例化放在静态代码块里可提高程序的执行效率，但也可能占用更大的空

is no relationship with the storage unit that Num points to, and of course it does not change the value in this storage unit. Therefore, the value is passed, passing the contents of the storage unit (8 basic types: value, non-basic type: The address of the actual object).2. What is reference deliveryonly values are passed in Java, and no reference is passed. The so-called reference pass is just a faul

finally {} after this try be executed, when it is executed, before or after it?Will execute, before return. 28th, Programming question: Calculate 2 times 8 in the most efficient way?Programmers with a C background are particularly interested in asking such questions. 2 29th, two object values are the same (x.equals (y) = = true), but can have different hash code, this sentence is correct?No, there's the s

;for (i=1;i{for (int k=1; kSystem.out.print ("");For (j=1;ji-1;j++)System.out.print ("");System.out.println ("");}for (i=4;i>=1;i--){for (int k=1; kSystem.out.print ("");For (j=1;ji-3;j++)System.out.print ("");System.out.println ("");}}}"Program 20"? Title: There is a fractional sequence: 2/1,3/2,5/3,8/5,13/8,21/13 ... to find out the sum of the first 20 items of this series.1. Program Analysis: Please grasp the molecular and the denominator of the law of change.public class Test20 {public stati

(throughput) collector?The throughput collector uses a parallel version of the new generation garbage collector, which 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.7. In Java, when can objects be garbage collected?This object can be recycled when the object becomes inaccessible to applications that currently use the o

machine is a common run error. The Java compiler requires the method to declare a non-runtime exception that might occur, but does not require that a runtime exception that is not caught to be thrown must be declared.7.: What is the result of the following program code output? public class smallt{public static void Main (String args[]) {Smallt t = new smallt ();int b = T.get ();System.out.println (b);}public int Get (){try {return 1;}Finally{return 2

second variable, it must be explicitly initialized. If you try to use it before it is initialized, the compiler will protest. If the initialized statement is in a try block or an if block, it must be assigned before the first use. That is, the compiler will also protest if the initialization statement is placed in a conditional judgment statement with only the If block, because execution may not conform to the judgment condition after the IF, so that the initialization statement is not executed

indicates whether the FETCH statement returns rows from the active set, such as a row is not returned, the value of this property isTrue? (select 1 items)A.%foundB.%notfoundC.%rowcountD.%isopenAnswer: B%found Boolean property, True if the record was last read successfully;%notfound boolean attribute, opposite to%found;%isopen Boolean property that returns TRUE when the cursor is open;%rowcount Numeric property, returns the number of records that have been read from the cursor212. Which clause i

Java programmer interview questions (86-115) 86. In Struts 2, how does Action obtain the data that the user inputs from the page, and how does it transmit its own data to the view? A: There are three ways for Action to retrieve data from the page: 1) accept parameters through the Action attribute 2) obtain parameters through the domain model 3) ModelDriven ) Action saves data to the Value Stack. View

forced transformation method return a Optional or Stream.Assume that the type of the object being passed is correct. Returns a optional or stream that includes the object.Otherwise, the returned optional or stream does not include whatever element.These methods are more trivial to implement:A new method on classPublic optionalWe are able to use FLATMAP to complete the filtering and casting steps:Implementation of Flatmap:stream> stream; May contain integersstreamThe wrong instance type or a nul

), a lower learning curve (developed in a similar way to C/s), easier to debug (less error type and easier to locate).(6) Dojo TookitDojo is a powerful object-oriented JavaScript framework. Mainly consists of three major modules: Core, Dijit, DojoX. Core provides AJAX, events, packaging, css-based querying, animations, JSON and other related operations Api,dijit is a replaceable skin, template-based WebUI control Library, Dojox includes some innovation/ Novel Code and Controls: Dategrid, charts,

The following are some of my java pen questions from my previous company. If you are interested, you can do them. --- Question --- 1. What is the output of the following program? Public class Foo { Public static void main (String [] args ){ Map Byte [] key = "abcd". getBytes (); M. put (key, "abcd "); System. out. println (m. containsKey (key )); System. out. println (m. containsKey ("abcd ")); System. out

hashset with Linkedhashset.8. Sort the collection There are many ways to sort a collection1.collections.sort (): Make a single order2.priorityqueue : The order of the queues is always maintained, but only the elements are fetched from the head of the queue3.TreeSet: Always keep the order of the queue, elements are not duplicated, you can get elements from the top or bottom, but you can't get the elements randomly9.collections.emptylist () vs new

system quickly fails to make a false error alarm immediately. In Java, quick failures are related to iterators. If a iterator is created on the collection object, other threads are "structured" to modify the collection object, and the concurrent Modification exception (Concurrentmodificationexception) is thrown.8, how to make HashMap synchronization?The HASHMAP can be synchronized by using map m = Collecti