1, Please select the return type of this method （）
Return Type method(byte x,double y){ return (short)x/y*2; }
A,byte
B,short
C,int
D,double
2, set up x=1,y=2,z=3, Then expression y+=z–/++x The value of is （）
A,3
B,3.5
C,4
D,5
3, Define the following two-dimensional array b, The following statement is correct （）
int b[][] = {{1,2,3},{4,5},{6,7,8}};
A,b.length The value of is 3
B,b[1].length The value of is 3
C,b[1][1] The value of is 5
D, Two dimensional array b The first dimension of 3 Elements
4, Set the following two assignment statements ：
a = Integer.parseInt(“12”); b = Integer.valueOf(“12”).inValue();
The following statement is correct （）
A,a Is an integer type variable ,b Is an integer class object
B,a Is an integer class object ,b Is an integer type variable
C,a and b Are integer class objects with equal values
D,a and b Are integer type variables with equal values
5, Below about HashMap What is true is that （）
A,HashMap Is thread safe , Can be used in multi-threaded environment
B,HashMap Insufficient capacity （ Threshold exceeded ） Hour , Will grow automatically
C,HashMap Is based on hash table , Is orderly
D,HashMap Realized Serializable Interface , So it supports serialization , Realized Cloneable Interface , Can be cloned
6, The following statement about inheritance is correct （）
A, stay Java Middle class only allows single inheritance
B, stay Java A class in can only implement one interface
C, stay Java A class in cannot inherit a class and implement an interface at the same time
D, stay Java Only single inheritance is allowed for interfaces in
7, The following is about the process , The thread statement is correct （）
A, Process is a dynamic execution process of a program , A process in its execution , Multiple threads can be generated —— Multithreading , Form multiple execution clues
B, Threads are smaller units of execution than processes , Is an independent control flow in a process , Control flow inside the program , The thread itself cannot run automatically , Dwell in a process , Process startup and execution
C,Java Multithreading is platform dependent
D, For single processor systems , Multi thread time slice acquisition CPU Or other system resources , For multiprocessor systems , Threads can be allocated to multiple processors , So as to truly execute multiple tasks concurrently
8, About which interface is correct （）
A, To implement an interface, all methods of the interface must be implemented
B, A class can implement only one interface
C, Interfaces cannot have inheritance relationship
D, Interfaces and abstract classes are the same thing
9, For statements that have been defined that may throw exceptions , During programming （）
A, Must use try/catch Statement handling exception , Or use throws Throw it out
B, If the program is wrong , Must use try/catch Statement handling exception
C, Can be ignored
D, Use only try/catch Statement processing
10, Below about Java Exception handling in try The right thing about the block is （）
A,try There should normally be one after the block catch block , Used to process try Exception thrown in block
B,catch Block must be followed by finally
C, Method calls that may throw exceptions should be placed in try In block
D, The handling of thrown exceptions must be placed in the try In block
11, The difference between a character stream and a byte stream is that （）
A, The former is buffered , The latter does not
B, The former is block read / write , The latter is byte read / write
C, There is no difference between the two , Interchangeable
D, The number of bytes read and written each time is different
12, The following belong to SQL Constrained by （）
A,NOT NULL
B,UNIQUE
C,ALTERNATE
D,CHECK
13, Of sql Aggregate functions are （）
A,sum
B,avg
C,count
D,min
14,SQL The order in which statements are executed is （）
A,1.SELETE 2.JAIN ON 3.FROM 4.WHERE 5.GROUP BY 6.HAVING 7.ORDER BY
B,1.SELETE 2.FROM 3.JAIN ON 4.WHERE 5.GROUP BY 6.HAVING 7.ORDER BY
C,1.FROM 2.JAIN ON 3.WHERE 4.GROUP BY 5.HAVING 6.SELECT 7.ORDER BY
D,1.JOIN ON 2.WHERE 3.GROUP BY 4.HAVING 5.SELECT 6.FROM 7.ORDER BY
15, Related to Spring Dao, The description error is （）
A, Convenient things Management ：Spring The declarative management of is class level
B,Spring Provided DAO Yes JDBC,JDO and Hibernate
C, Abnormal packaging ：Spring Able to pack Hibernate abnormal , Take them from CheckdException Become RuntimeException; Developers can choose to handle unrecoverable exceptions in the data at the appropriate layer , To avoid tedious catch/throw And exception statement
D,Spring Provided DAO（ Data access object ） The main purpose of the support is to facilitate the use of different data access technologies in a standard manner
16, about Spring AOP Implementation mechanism of , The error in the following description is （）
A,JDK Dynamic proxy , yes Java Agent technology provided , A proxy instance of an interface can be created at load time
B,Spring AOP Default use JDK Dynamic proxy , Weaving code into a proxy instance of an interface
C,CGLIB Dynamic proxy , Using the underlying bytecode Technology , Create a subclass proxy instance at run time
D, When the target object does not have an interface ,Spring AOP Will adopt CGLIB Dynamic proxy mode , Weaving code into subclass instances
17, Which of the following comments is in spring As a matter of control （）
A,@Transaction
B,@Transactional
C,@Service
D,@Autowired
18, Which of the following can be used to retrieve session attribute userid Value of （）
A,session.getAttribute(“userid”);
B,session.setAttribute(“userid”);
C,request.getParameter(“userid”);
D,request.getAttribute(“userid”);
19, The following about Session In the description of , The wrong thing is （）
A,Session Stored on the server
B, By default ,Session Dependent on Cookie
C,Session Only strings can be stored in , Cannot store other types of data
D, In a distributed architecture , existence Session Shared issues
20, about HTTP Status code , The following statement is correct （）
A,200 representative OK
B,404 Delegate requested resource not found on server
C,403 The change request was rejected on behalf of the server
D,500 Invalid request received from upstream on behalf of server
21,Java Modes include many , among Spring Which two basic design patterns are implemented ?
22, Please brief Springboot and SpringMvc Differences between
23, Please list Spring among ioc Four injection methods
24, What is a thread ? What is the process ? What are the differences and connections between the two ?
25, Please tell us the difference between greedy algorithm and dynamic programming ?
26, Existing student form （t_student） as follows ：
idnonamecoursecourse_idgrade
12005001 Zhang San 0001 mathematics 69
22005002 Lisi 0001 mathematics 89
32005001 Zhang San 0001 mathematics 69
Please write one SQL sentence , Used to delete except id Different , Redundant information of other students with the same information
27, Please use Java Write a bubble sorting method from small to large
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