java code review interview questions

I. Application of the factory model in development Interview Questions:Write a simple calculator. Code implementation: Abstract An operation class: Package COM. qianyan. calcuator; public abstract class operation {// number one private double num1; // number two private double num2; Public double getnum1 () {return num1;} public void setnum1 (double num1) {This. num1 = num1;} public double getnum2 () {ret

. Object-oriented computing begins with the basic concept that the real world can be depicted as a series of completely autonomous and encapsulated objects that access other objects through a protected interface. 4. Polymorphism: allows different types of objects to respond to the same message. Polymorphism includes parameterized polymorphism and inclusion polymorphism. The polymorphism language has the advantages of flexibility, abstraction, behavior sharing, and

1. What is acitsag startup mode? For such a question, I will write an example myself. I will observe it to understand it. Activty supports four startup modes. Launchmode: Standard: each time a new activity window is started (New Operation) Singletop: if it is a target activity at the top of the stack, It will be opened directly. Otherwise, a new activity window (new) will be opened ). Singletask and singleinstance are basically the same. The difference is that if the root activity is set to sing

();// Here is a static method for external access to this class, which can be accessed directly.Public static Singleton getInstance (){Return instance;}} Second form: Public class Singleton {Private static Singleton instance = null;Public static synchronized Singleton getInstance (){// This method is better than above. You don't need to generate objects every time. It's just the first time.// Generate instances during use, improving efficiency!If (instance = null)Instance = new

The following questions will be used:4Tables. For details about the fields in these four tables, refer to the following content: Employees (employee_id number (6) Not null, first_name varchar2 (20), last_name varchar2 (25) not null, email varchar2 (25) not null, phone_number varchar2 (20 ), hire_date date not null, job_id varchar2 (10) Not null, salary number (8, 2), commission_pct number (2, 2), manager_id number (6), department_id number (4 ))

. After the sleep interval expires, the thread may not resume execution immediately. This is because at that time, other threads may be running and not scheduled to give up execution, unless (a) the thread "wakes up" has a higher priority (B) the running thread is blocked for other reasons.When wait () is a thread interaction, if the thread sends a wait () call to a synchronization object X, the thread will pause the execution and the called object will enter the waiting state, wait until the wa

difference between the 5.sendRedirect () and Forward () methods?The Sendredirect () method creates a new request, and the forward () method simply forwards the request to a new target. After redirection (redirect), objects that were within the scope of the previous request are invalidated because a new request is generated, and after forwarding (forwarding), objects within the scope range of the previous request can be accessed. Sendredirect () is generally considered to be slower than forward

This is the topic discussed during the last interview and is recorded. Spring Why use spring? What are the benefits of IOC? What are the benefits of scalability? How to instantiate a bean? What is the difference between applicationcontext and beanfactory? How can I read external files through spring? Can bean IDS be repeated in the spring configuration file? What is automatic assembly and type check in spring? Can applicationco

the final method, instead of making routine method calls, such as saving breakpoints and pushing stacks, this may improve the efficiency of your program. However, when your method subject is very large, or if you call this method in multiple places, your caller Code It will expand rapidly, but may affect efficiency. Therefore, use final for method definition with caution.Final classWhen using final on a class, you need to consider it carefully. Becau

1. What is Java ee?A: Java EE is a multi-layer (Multi-diered), distributed (distributed), and component-based enterprise-level application model (enterpriese application model) proposed by Sun ). In such an application system, different components can be divided by function. These components can be located on different computers and at the corresponding level (Tier. The hierarchy includes the Client layer (

The dashed box represents the interface, the solid wireframe represents the entity class, The thick wireframe represents the most commonly used entity classes, the dashed arrows indicate the implementation of the interface, and the implementation arrows indicate that the class can make objects of the class that the arrows refer to. Collection: Allows only one object to be placed in each location. It includes a list of "holding a set of objects in a certain order", and a set that "only allo

Requirements: Compile a function to intercept a string. The input is a string and number of characters, and the output is a string truncated by bytes. However, make sure that no half of Chinese characters are cut, for example, "my ABC" 4, it should be cut to "my AB", input "my ABC Han DEF", 6, the output should be "I abc" instead of "I ABC + Han ". Basic knowledge: First, let's take a look at the basic units:1. bit is a binary bit. For example, 100011 is 6 bits.2. bytes (byte), which is the most

. Statement A: Within the connection, only those rows whose values satisfy the join conditions in the public column are displayed. Statement B: For outer joins, the result set contains all rows from one table and a matching row from another table, and if a matching record is not found in the related table, the column appears null. Statement C: In a cross connection between two tables, each row of the first table is connected to each row of the second table. Statement d: A self-connection is a ro

piece of data, which applies to data that is often read but rarely updated* Transactional: This strategy is a fully transactional cache strategy, can be used in JTA environment 7, hibernate inside the sorted collection and ordered collection what is the difference Sorted collection is sorted in memory through the Java comparerThe ordered collection is the 8, hibernate, and why they are sorted in the database by ordering by. 1. Read and resolve confi

. When a thread is running, it is paused, usually to wait for a certain time to occur (for example, a resource is ready) before continuing. Methods such as sleep,suspend,wait can cause threads to block. The five is the state of death. If a thread's Run method finishes or calls the Stop method, the thread dies. For a dead thread, you cannot use the Start method to get it ready (7) Multithreading security issues: In summary, multiple threads in the execution of the same piece of