inotgo.com

Example 1 : What are the characteristics of object-oriented ?   
Example 2 : String Is it the most basic data type ?   
Example 3 : int and Integer What's the difference? ?   
Example 4 : String and StringBuffer The difference between ?   
Example 5 : What are the similarities and differences between runtime exceptions and general exceptions ?   
Example 6 : give voice ArrayList,Vector, LinkedList Storage performance and characteristics .   
Example 7 : Collection and Collections The difference between .   
Example 8 : & and && The difference between   
Example 9 : HashMap and Hashtable The difference between   
Example 10 : final, finally, finalize The difference between   
Example 11 : Overload and Override The difference between , That is, the difference between overloading and rewriting . Overloaded Whether the method of can change the type of return value ?   
Example 12 : Error and Exception What's the difference? ?   
Example 13 : abstract class and interface What's the difference? ?   
Example 14 : heap and stack What's the difference?   
Example 15 : GC What is it? ? Why should there be GC?   
Example 16 : short s1 = 1; s1 = s1 + 1; What's wrong ?   
Example 17 : Math.round(11.5) Equal to how much ? Math.round(-11.5) Equal to how much ?   
Example 18 : String s = new String("xyz"); Created several String Object?   
Example 19 : Java Is there any goto?   
Example 20 : Whether the interface can inherit the interface ? Whether the abstract class can be implemented (implements) Interface ? Whether the abstract class can inherit the entity class (concrete class)?   
Example 21 : List, Set, Map Whether inherited from Collection Interface ?   
Example 22 : abstract of method Whether it can be static, Whether it can be synchronized?   
Example 23 : Does the array have length() This method ? String Is there any length() This method ?   
Example 24 : Set The elements in the can't be repeated , So what is the method to distinguish repetition from non repetition ?   
Example 25 : Constructor Constructor Whether it can be override? Whether you can inherit String class ?   
Example 26 : switch Whether it can act on byte Go ahead , Whether it can act on long Go ahead , Whether it can act on String Go ahead ?   
Example 27 : try {} There is one in the return sentence , So follow this try After finally {} In the code Will it be executed , When will it be executed , stay return Before or after ?   
Example 28 : Two objects have the same value (x.equals(y) == true), But there are different hash code, Is this right ?   
Example 29 : Advantages and principles of garbage collection . And consider 2 A recycling mechanism .   
Example 30 : What are the collection classes you know ? The main method ?   
Example 31 : char Can a Chinese character be stored in type variable ? Why? ?   
Example 32 : analysis XML There are several ways to document ?   
Example 33 : keyword :throws,throw,try,catch,finally What do they mean ? stay try Can an exception be thrown in a block ?   
Example 34 : One ".java" Whether multiple classes can be included in the source file ( Not an inner class )? What are the limitations ?   
Example 35 : java There are several types of flows in ?   
Example 36 : java Will there be a memory leak in , Please briefly describe .   
Example 37 : java What is the mechanism for implementing polymorphism in ?   
Example 38 : The difference between static variables and instance variables ?   
Example 39 : What is? java Serialize , How java Serialize ?   
Example 40 : Can we start from a static Method to issue a non - static Method call ?   
Example 41 : stay JAVA In , How to jump out of the current multiple nested loop ?   
Example 42 : List、Map、Set Three interfaces , When accessing elements , What are the characteristics of each ?   
Example 43 : Anonymous Inner Class ( Anonymous inner class ) Whether it can be or not? extends( Inherit ) Other classes , Whether it can be or not? implements( realization )interface( Interface )?   
Example 44 : Can an inner class reference members of an outer class ? Are there any restrictions ?   
Example 45 : There are several ways to implement multithreading , What are they ?   
Example 46 : sleep() and wait() What's the difference? ?   
Example 47 : What is the working mechanism of data connection pool ?   
Example 48 : sketch synchronized and java.util.concurrent.locks.Lock The similarities and differences between ?   
Example 49 : Class.forName The role of ? Why use ?   
Example 50 : When a thread enters a of an object synchronized After the method , Whether other threads can enter other methods of this object   
Example 51 : Give me five of the most common things you see runtime exception.   

Example 1 :

What are the characteristics of object-oriented ?

edit top fracture
Encapsulate
The most common is to encapsulate property privatization in a class , Can only be accessed through methods
Inherit
The subclass inherits the parent class , Thus, it inherits the methods and properties of the parent class
Abstract
Like a hero , Abstract Something went wrong name,hp These properties , Make the development process easier to understand
Polymorphism
Polymorphism of operator and class . Class polymorphism means that the parent class reference points to the child class object , And there is inheritance , There are rewrites .
Example 2 :

String Is it the most basic data type ?

edit top fracture
String Is a class type , Not a basic type .
Basic types There are eight
The eight basic types are :
integer (4 species )
character (1 species )
float (2 species )
Boolean (1 species )
Example 3 :

int and Integer What's the difference? ?

edit top fracture
int It's the basic type 32 Bit length integer

Integer Is a class type , yes int of Encapsulation class

int and Integer Can pass through Automatic packing Automatic unpacking Mutual conversion
Example 4 :

String and StringBuffer The difference between ?

edit top fracture
String yes immutable of , Once the content is created , You can't change .
StringBuffer It can grow , The content can also change
The principle of change is StringBuffer The internal character array is used to store data , When the length needs to be increased , Create a new array , And copy the original data to a new array .
For more details, please refer to Imitate StringBuffer of MyStringBuffer How classes are implemented .
Example 5 :

What are the similarities and differences between runtime exceptions and general exceptions ?

edit top fracture
Runtime exception Also known as non verifiable exception , During compilation , Display capture is not required
General exception Also known as verifiable exception , During compilation , Must be handled , Or capture , Either through throws Throw it out .
Example 6 :

give voice ArrayList,Vector, LinkedList Storage performance and characteristics .

edit top fracture
Let's start with ArrayList and Vector
Both inherit abstract classes AbstractList, But Vector yes Thread safe , and ArrayList Is non thread safe

Besides ArrayList and LinkedList The difference between
ArrayList Is an array structure , So positioning is fast , But insertion and deletion are slow
LinkedList It is a two-way linked list structure , So insert and delete quickly , But positioning is slow
Example 7 :

Collection and Collections The difference between .

edit top fracture
first Don't say One is singular , One is plural ...
Collection It's the interface , yes List and Set Parent interface of
Collections It is a tool class , Provides sorting , Confusion and many other practical methods
Example 8 :

& and && The difference between

edit top fracture
& It has two functions , namely Bit and and Logic and
&& Is logic and
As logic and , & and && Respectively represent Long circuit and short circuit
Long road and both sides , Will be calculated
Short circuit and As long as the first one is false, The second one doesn't operate
Example 9 :

HashMap and Hashtable The difference between

edit top fracture
HashMap and Hashtable It's all done Map Interface , They are the way key value pairs save data
difference 1:
HashMap Can store null
Hashtable Cannot store null
difference 2:
HashMap no Thread safe classes
Hashtable Is a thread safe class
Example 10 :

final, finally, finalize The difference between

edit top fracture
final
final Modifier class , method , Basic type variables , When quoting, they have different meanings
Modifier class Indicates that this class cannot be inherited
Modification method Indicates that the method cannot be overridden
Modify basic type variables Indicates that the variable can only be assigned once
Modifier reference Indicates that the reference has only one chance to point to the object
finally
finally Is a scene for exception handling , Whether or not an exception is thrown , Will be implemented
finalize
finalize yes Object How to , All classes inherit this method . When an object satisfies the garbage collection condition , And when it's recycled , Its finalize() Method will be called
Example 11 :

Overload and Override The difference between , That is, the difference between overloading and rewriting . Overloaded Whether the method of can change the type of return value ?

edit top fracture
Overload It's the way Overload I mean , It means in the same class , The method name is the same , But the parameters are different
Override It's the way rewrite I mean , It refers to that after a subclass inherits a method of the parent class , Write it again
Overloaded Whether the method of can change the type of return value ?
sure , Overloading is essentially a completely different approach , Just just right Took the same name
Example 12 :

Error and Exception What's the difference? ?

edit top fracture
Error and Exception It's all done Throwable Interface

Error refer to JVM Level of error , For example, there is not enough memory OutOfMemoryError

Exception It refers to the exception of code logic , For example, the subscript is out of bounds OutOfIndexException
Example 13 :

abstract class and interface What's the difference? ?

edit top fracture
abstract class Abstract classes and interface Interface The difference between

Mode of use :
Abstract classes can only be used through inheritance
The interface must be used through implementation

Implementation method :
Abstract classes can not only provide abstract methods , You can also provide implementation methods
Interfaces can only provide abstract methods , Cannot provide an implementation method . But in JAVA8 Version start , Interface can provide implementation methods , The premise is to add a before the method default Modifier
Example 14 :

heap and stack What's the difference?

edit top fracture
heap: Pile
stack: Stack ( In some books , Will be translated into stack , In fact, it refers to the simple Stack )

The contents stored are different :
heap: Is the storage of objects
stack: Is the basic type of storage (int, float, boolean wait )、 quote ( Object address )、 Method call

Different access methods :
heap: It automatically increases the size , So you don't need to specify the size , But access is relatively slow
stack: It's a fixed size , And it's FILO First in then out , And the access speed is relatively fast
Example 15 :

GC What is it? ? Why should there be GC?

edit top fracture
GC yes Garbage Collection Abbreviation for , Garbage collection
The so-called garbage here , Refers to objects that are no longer used ,JVM The garbage collection mechanism makes developers from boredom 、 Error prone manual release of memory resources .
Developers can focus more on the development of business functions , The work of resource recovery is automatically completed by a more professional garbage collection mechanism .
Example 16 :

short s1 = 1; s1 = s1 + 1; What's wrong ?

edit top fracture
short s1 = 1; There is no mistake in this sentence , The compiler will automatically 1 This integer is treated as short.
s1 = s1 + 1; The expression on the right will return a Int Integer of type , Put this again int Assign an integer of type to short Type of s1 When I was , There will be a cast error
Example 17 :

Math.round(11.5) Equal to how much ? Math.round(-11.5) Equal to how much ?

edit top fracture
Math.round I mean +0.5 Take an integer
So Math.round(11.5) That is 11.5+0.5 = 12
Math.round(-11.5) That is -11.5+0.5 = -11
Example 18 :

String s = new String("xyz"); Created several String Object?

edit top fracture
String s = new String("xyz");
First, construct the method new String("xyz"); In "xyz" This itself is a string object
then new Keyword must create an object
So a total of two String Object
have ,goto Is a keyword , But it's a reserved word , Not functional
Example 20 :

Whether the interface can inherit the interface ? Whether the abstract class can be implemented (implements) Interface ? Whether the abstract class can inherit the entity class (concrete class)?

edit top fracture
Whether the interface can inherit the interface ?
sure , For example List It inherits the interface Collection
Whether the abstract class can be implemented (implements) Interface ?
sure , For example MouseAdapter Mouse monitor adapter Is an abstract class , And realized MouseListener Interface
Whether the abstract class can inherit the entity class (concrete class)?
sure , All abstract classes , All inherited Object
Example 21 :

List, Set, Map Whether inherited from Collection Interface ?

edit top fracture
List and Set Inherited Collection Interface

But Map and Collection There is no inheritance relationship between , Because one is a key value pair container , One is a single value container , Incompatible
List, Set, Map Whether inherited from Collection Interface ?
Example 22 :

abstract of method Whether it can be static, Whether it can be synchronized?

edit top fracture
abstract of method Whether it can be static, Whether it can be synchronized?

Not at all
Example 23 :

Does the array have length() This method ? String Is there any length() This method ?

edit top fracture
The way to get the length of an array is .length attribute
String The way to get the length is length() method
The way to get the length of a collection is size() method
The way to get the length of a file is length() method
Example 24 :

Set The elements in the can't be repeated , So what is the method to distinguish repetition from non repetition ?

edit top fracture
With HashSet take as an example , The logic of judging repetition is :
1. First look at hashcode Is it the same , If different , Just don't repeat
2. If hashcode equally , Compare equals, If different , Just don't repeat , Otherwise, it will be repeated .

More about hashcode The principle of , reference resources Java HashCode Detailed explanation of principle
Example 25 :

Constructor Constructor Whether it can be override? Whether you can inherit String class ?

edit top fracture
A subclass cannot inherit the constructor of the parent class , Therefore, there is no constructor that overrides the parent class .
notes : super() Indicates that the subclass calls the constructor of the parent class , This cannot be called a constructor that inherits the parent class

String yes final Decorated , So it can't be inherited
Example 26 :

switch Whether it can act on byte Go ahead , Whether it can act on long Go ahead , Whether it can act on String Go ahead ?

edit top fracture
switch Can act on byte,short,int String,Enum( Enumerate ) Go ahead , But it can't work on long above

notes : notes :switch Act on String From JDK1.7 Start support , The essence is to replace the string with its corresponding... At compile time hash value
Example 27 :

try {} There is one in the return sentence , So follow this try After finally {} In the code Will it be executed , When will it be executed , stay return Before or after ?

edit top fracture
try In the return and finally In the return Will be implemented , But the current approach will only adopt finally In return The value of
Example 28 :

Two objects have the same value (x.equals(y) == true), But there are different hash code, Is this right ?

edit top fracture
Because hashCode() Methods and equals() Methods can be overridden by custom classes , yes Can do equals Same , But hashCode different

But , stay Object Class equals() There is a passage in the method

* Note that it is generally necessary to override the {@code hashCode}
* method whenever this method is overridden, so as to maintain the
* general contract for the {@code hashCode} method, which states
* that equal objects must have equal hash codes.

Translate as follows :

Generally speaking , When rewriting this method , You also need to be right hashCode Method ,
So as to ensure the consistency of the two methods ——
When equals return true When I was , These two objects must have the same hashcode.


Two objects have the same value (x.equals(y) == true), But there are different hash code, Is this right ?
So the answer to this question should be no , But we have to find out what's inside
 Two objects have the same value (x.equals(y) == true), But there are different hash code, Is this right ?
Example 29 :

Advantages and principles of garbage collection . And consider 2 A recycling mechanism .

edit top fracture
With C Language developers need to release memory resources manually ,Java Provide garbage collection mechanism , Automatic GC, Liberate developers from error prone memory resource management .

Principle : When an object , When there is no reference to it , Then it meets the conditions of garbage collection , In due course ,JVM The virtual machine is used for GC Recycle it , Free up space , For subsequent reuse .

Two common recycling mechanisms :
1. Timing recovery
Every 30 Recycle once a minute , The disadvantage of this mechanism is that if garbage is generated faster , be on the cards 30 Garbage has run out of memory in minutes , Resulting in slower performance

2. When garbage accounts for a certain percentage , Recycle
For example , When garbage takes up 70% When I was , Recycle . The disadvantage of this mechanism is , If the frequency of garbage generation is fast , So JVM We must carry out garbage collection with high frequency . And in the process of garbage collection , JVM Will pause , Just garbage collection , And affect the normal operation of business functions .

Generally speaking JVM Garbage collection will be carried out by combining the two mechanisms .
Example 30 :

What are the collection classes you know ? The main method ?

edit top fracture
Common collections
ArrayList,LinkedList,HashSet,HashMap,TreeSet wait
Common methods :
size()
add()
remove()
wait
Example 31 :

char Can a Chinese character be stored in type variable ? Why? ?

edit top fracture
char yes 16 Bit , Two bytes
Chinese characters usually use GBK Or UNICODE code , It also uses two bytes
So you can store Chinese characters
Example 32 :

analysis XML There are several ways to document ?

edit top fracture
There are mainly two ,SAX and DOM
SAX Is to read line by line , Until the target data is found

DOM Is to load the full document first , Then read
Example 33 :

keyword :throws,throw,try,catch,finally What do they mean ? stay try Can an exception be thrown in a block ?

edit top fracture
throws Used on method declarations , Indicates that the method may throw an exception
throw Throw a specified exception
try catch stay try It is possible to throw an exception , Once an exception is thrown , Will be in catch Snap in , They both Generally speaking They all appear in pairs .
finally: Indicates whether an exception is caught or not , Will be implemented
Example 34 :

One ".java" Whether multiple classes can be included in the source file ( Not an inner class )? What are the limitations ?

edit top fracture
Can include multiple classes , But only one public Modified class , However, there can be multiple non public Modified class .
Example 35 :

java There are several types of flows in ?

edit top fracture
Java All flows in are based on Byte stream , So the basic flow is
Input / output byte stream
InputStream
OutputStream
On the basis of byte stream , Encapsulates Character stream
Reader
Writer
Further , Encapsulated again Cache stream
BufferedReader
PrintWriter
as well as Data flow
DataInputStream
DataOutputStream
Object flow
ObjectInputStream
ObjectOutputStream

And some other weird streams ~~~
Example 36 :

java Will there be a memory leak in , Please briefly describe .

edit top fracture
Because Java It is used for automatic garbage collection management , So it doesn't exist C Memory leakage of equivalent concepts in language , But there is Java characteristic Memory leak

When some objects are not used , But there are times when indirect references point to , Then the conditions for garbage collection are not met , And form a memory leak .

For example, the example in the code , Everyone Object When it was created , There is a reference o Point to , Then it was put into the collection al In . next Object When it was created , the previous Object There is no reference to .

these Object There is no reference to , But it's on ArrayList In , And this Arraylist Forgot to recycle , So all the objects inside , Will survive forever , Although it is no longer used .
package j2se; import java.util.ArrayList; public class MemoryLeak { static ArrayList<Object> al = new ArrayList<Object>(); public static void main(String[] args) { for (int i = 0; i < 100; i++) { Object o = new Object(); al.add(o); } } }
package j2se;

import java.util.ArrayList;

public class MemoryLeak {
	static ArrayList<Object> al = new ArrayList<Object>();

	public static void main(String[] args) {

		for (int i = 0; i < 100; i++) {
			Object o = new Object();
			al.add(o);
		}

	}
}
Example 37 :

java What is the mechanism for implementing polymorphism in ?

edit top fracture
Conditions for polymorphism of classes :
1. Parent class ( Interface ) The reference points to a subclass object
2. Methods have overrides
Example 38 :

The difference between static variables and instance variables ?

edit top fracture
Static variables You can access... Directly through classes , No instance required

Instance variable For example, through a specific instance of a class , To access
Example 39 :

What is? java Serialize , How java Serialize ?

edit top fracture
Serialization refers to putting a Java Object , Transmission through a medium , For example Socket Input / output stream , Or save it in a file

realization java Serialization means that the class implements the interface Serializable, This interface is an identifying interface , There is no way , Only used to indicate that the class can be serialized .
Example 40 :

Can we start from a static Method to issue a non - static Method call ?

edit top fracture
no way , Because it's not static Method needs a concrete instance to call , And call static When the method , There may not be an instance
Example 41 :

stay JAVA In , How to jump out of the current multiple nested loop ?

edit top fracture
On the first line of the external loop , Label
stay break Use this label when
That is, it can end multiple nested loops
public class HelloWorld { public static void main(String[] args) { // Print odd number outloop: //outloop This sign can be customized, such as outloop1,ol2,out5 for (int i = 0; i < 10; i++) { for (int j = 0; j < 10; j++) { System.out.println(i+":"+j); if(0==j%2) break outloop; // If it's an even number , End the external loop } } } }
public class HelloWorld {
    public static void main(String[] args) {
          
        // Print odd number      
        outloop: //outloop This sign can be customized, such as outloop1,ol2,out5
        for (int i = 0; i < 10; i++) {
             
            for (int j = 0; j < 10; j++) {
                System.out.println(i+":"+j);
                if(0==j%2)  
                    break outloop; // If it's an even number , End the external loop 
            }
             
        }
         
    }
}
Example 42 :

List、Map、Set Three interfaces , When accessing elements , What are the characteristics of each ?

edit top fracture
List It's sequential , And can repeat
Set Is disordered , Do not repeat ( reference resources How to judge Set Whether the objects in the are duplicated )
Map The way to save data is key value pairs
Example 43 :

Anonymous Inner Class ( Anonymous inner class ) Whether it can be or not? extends( Inherit ) Other classes , Whether it can be or not? implements( realization )interface( Interface )?

edit top fracture
Anonymous inner classes are essentially inheriting other classes , Implement other interfaces

For example :
Anonymous class 1, Is to inherit Thread
Anonymous class 2 , Is to achieve Runnable Interface
package j2se; public class HelloWorld { public static void main(String[] args) { // Anonymous class 1 new Thread() { public void run() { } }; // Anonymous class 2 new Runnable() { public void run() { } }; } }
Example 44 :

Can an inner class reference members of an outer class ? Are there any restrictions ?

edit top fracture
have access to
If it is a non static inner class , You can use all members of an external class
If it is a static inner class , Only static members of external classes can be used
Example 45 :

There are several ways to implement multithreading , What are they ?

edit top fracture
Generally speaking ,Java There are three ways to create a thread
1. Inherit one Thread class
2. realization Runnable Interface
3. Anonymous inner class
For details, please refer to Java There are three ways to create a thread
Example 46 :

sleep() and wait() What's the difference? ?

edit top fracture
first sleep and wait There is no relationship between

sleep yes Thread Class method , It refers to the current thread pause .

wait yes Object Class method , The thread occupying the current object temporarily releases the occupation of the current object , So that other threads have the opportunity to occupy the current object . So call wait The method must be in synchronized In
Example 47 :

What is the working mechanism of data connection pool ?

edit top fracture
Principle of database connection pool :
Because the behavior of creating and closing connections is very time-consuming , It will significantly reduce the performance of the software . The solution is to create n Database connections Connection, Recycling , But do not close , Then execute SQL sentence , There is no need to create additional connections , Just use an existing connection , This saves the time overhead of creating and closing connections .

reference resources Design a database connection pool class :ConnectionPool
Example 48 :

sketch synchronized and java.util.concurrent.locks.Lock The similarities and differences between ?

edit top fracture
1. Lock Is an interface , and synchronized yes Java Keywords in ,synchronized Is a built-in language implementation ,Lock It's a code level implementation .

2. Lock You can selectively obtain locks , If you can't get it for a while , Can give up .synchronized no way , Will keep getting it all the time . With the help of Lock This feature of , Can avoid deadlock ,synchronized It must be through careful and good design , In order to reduce the occurrence of deadlock .

3. synchronized When an exception occurs and the synchronization block ends , Will automatically release the lock . and Lock Must be released manually , So if you forget to release the lock , It will also cause deadlock .

complete Lock See the tutorial : Lock Object
Example 49 :

Class.forName The role of ? Why use ?

edit top fracture
Class.forName A common scenario is to call... During database driver initialization .

Class.forName Its meaning is to load the class into JVM In . Once a class is loaded into JVM In , Its static properties will be initialized , During initialization, the relevant code will be executed , So as to achieve " Effect of loading driver "
Example 50 :

When a thread enters a of an object synchronized After the method , Whether other threads can enter other methods of this object

edit top fracture
It depends , If other methods of the object also have synchronized Decorated , Then other threads will be blocked out . Otherwise, other threads can enter other methods .
Example 51 :

Give me five of the most common things you see runtime exception.

edit top fracture
NullPointerException Null pointer exception
ArithmeticException Arithmetic anomaly , For example, the divisor is zero
ClassCastException Type conversion exception
ConcurrentModificationException Synchronous modification exception , When traversing a collection , Delete the elements of the collection , Will throw the exception
IndexOutOfBoundsException Array subscript out of bounds exception
NegativeArraySizeException The space allocated for the array is negative, exception


The official account of programming , Follow and get the latest tutorials and promotions in real time , thank you .


Q & A area    
2020-10-20 Is a class type a reference data type ??
Xiao Zhu 666

Is a class type a reference data type ??




1 One answer

Blink_tangjinxin
Answer time :2020-10-24
yes



The answer has been submitted successfully , Auditing . Please My answer Check the answer record at , thank you
answer Or code please Fill in at least one , If you have a problem , Please ask again , Otherwise, the webmaster may not see




2020-05-19 math.floor and math.round The difference is
WANGMING123

How to distinguish math,floor and math.round? It's simple , Directly math.floor Look at it as a floor , You can know to take the minimum value , To know math.round Used to get the maximum , So there won't be any mistakes




1 One answer

The general died in a hundred battles
Answer time :2020-07-10
Math.floor(): floor It means floor . That is, round down ( Integers erase decimals directly , Negative numbers -11.5 Rounding is -12) Math.round(); It's rounding ( rounding ). Equivalent to... First +0.5 Round down again .(1.1+0.5 Round down or 1 1.5+0.5 Rounding down is 2, Add 0.5 To achieve 5 enter ,)



The answer has been submitted successfully , Auditing . Please My answer Check the answer record at , thank you
answer Or code please Fill in at least one , If you have a problem , Please ask again , Otherwise, the webmaster may not see




2020-05-04 Example 17, about Math.round
2019-11-12 Hello, stationmaster ! Would you like to ask if the following questions will be updated regularly ?
2019-11-10 There is no multithreading , Will this be asked in the interview


Too many questions , Page rendering is too slow , To speed up rendering , Only a few questions are displayed on this page at most . also 12 Previous questions , please Click to view

Please... Before asking questions land
The question has been submitted successfully , Auditing . Please My question Check the question record at , thank you
about Interview questions -J2SE-JAVA Interview questions Your questions

Try to provide Screenshot code and Abnormal information , Help to analyze and solve problems . You can also enter this station QQ Group communication : 496725845
Ask questions and try to provide complete code , Environment description , The more conducive to the recurrence of the problem , The faster your question can be answered .
Have questions about the code in the tutorial , Please provide which step , Which line is in doubt , This makes it easy to quickly locate the problem , Improve the speed at which questions are answered
In the thousands of questions that already exist , A considerable proportion , Because of the use of and webmaster Different versions of the development environment Resulting in , For example jdk, eclpise, idea, mysql,tomcat Wait, the version of the software is inconsistent .
Please use the same version as the webmaster , You can save yourself a lot of learning time . The webmaster sorted out the software versions used in teaching , It's all here , Convenient for everyone to download : /k/helloworld/helloworld-version/1718.html

Upload screenshot