Code quality management

1 Make pushDataList a static final constant or non-public and provide accessors if needed.

Class variable fields should not have public accessibility . So the public Access modifier , Change to other modifiers , It is best to private.

Public class variable fields don't respect encapsulation principles , There are three main drawbacks ：
Can't add other behavior , Such as verification .
The internal representation is public , You can't change it later .
Member values can change anywhere in the code , And it may not fit the programmer's assumptions .
By using private properties and accessor methods （set and get）, Can prevent unauthorized modification .

There's no good reason not to declare fields “final” In this case, declare the field “public” and “static”. Most of the time , This is an error sharing state between multiple objects . But in this way , Any object can do whatever it wants with the shared state , For example, set it to null .

2 Use Galois/Counter Mode (GCM/NoPadding) instead

3 Remove this call to “equals”; comparisons between unrelated types always return false.

Delete the "equals" Call to ; Comparisons between unrelated types always return false.

   if (transportTask.getTaskType().equals("1") || transportTask.getTaskType().equals("4")) {}
   
transportTask.getTaskType() by Short type , therefore if Forever false
short  The data type is  16  position 、 A signed integer represented by a binary complement 
 The minimum is  -32768（-2^15）;
 The maximum is  32767（2^15 - 1）;
Short  Data types can also be like  byte  That saves space . One short A variable is int One-half of the space occupied by the type variable ;
 The default value is  0;

 Example ：short s = 1000,short r = -20000.
short It will be promoted to int Type or higher . This is because Java Will automatically short Data is treated as a int The literal value of the type （literal） To deal with .byte The same is true when types do operations , Will be java Automatically upgrade the level .

short  yes  Java  The original type .short  Variables can be stored 16 A signed integer .
Short  Class is  short  Wrapper object class of original type . It defines the range of values that represent this type  MIN_VALUE  and  MAX_VALUE  Constant .
Java  All integer values in are  32  Bit  int  value , Except after the value  l  or  L（ Such as  235L）, This means that the value should be interpreted as  long.

4 Cast one of the operands of this integer division to a “double”

        Cast one of the operands of this division operation to a "double"

Convert one operand of this division operation to "double"

Very basic , In the coding process , Mistakes that are easy to be ignored , Divide two integers , The result must be an integer ,
If you use float、double Wait for data type reception , Grammar does not constitute a mistake , But it will lose precision .

/**

• @author css

• @date 2019/9/30 9:39
  */
  public class Test {
  public static void test(double d){
  System.out.println(d);
  }

  public static void main(String[] args) {
  int a = 1;
  int b = 2;
  test(a/2);
  float c = a/b;
  System.out.println;
  // here c The value of loses precision
  }
  }

//Idea Warning ： Integer division in floating-point context
integer division in floating-point context

5 Sonar Tips ： Use “BigDecimal.valueOf” instead.

 resolvent ： Use BigDecimal.valueOf() Instead of . Because this method internally converts parameters to String, Ensure the accuracy is not lost .

    public static BigDecimal valueOf(double val) {
        return new BigDecimal(Double.toString(val));
    }

6 Either re-interrupt this method or rethrow the “InterruptedException”.

It is amended as follows ：

7 Do something with the “boolean” value returned by “delete”.

Prompt when the operation status code is included , The return value... Should not be ignored . In other words, the result of file deletion should not be ignored .
Therefore, the following modifications are made , However, the following modifications fix the vulnerability , But there's a new smell .

Odor tips "java.nio.Files#delete" should be preferred (squid:S4042). You should use Files.delete() Method , Not between files delete. So it was finally revised to ：

8 Use a logger to log this exception.

It is amended as follows ：

9 Unusual IllegalAccessException

java.lang.IllegalAccessException: Class com.study.reflect.ref_test.Tool can not access a member of class com.study.reflect.ref_test.Student with modifiers “private”
IllegalAccessException Indicates an exception without access .
Class com.study.reflect.ref_test.Tool can not access a member of class com.study.reflect.ref_test.Student with modifiers “private”
tool Class not accessible student Members of the .
This permission access is abnormal , It's because I didn't remove permission when I used violent reflection to obtain bytecode objects , That is to say setAccessible(true)

10 Use an “instanceof” comparison instead.

It is amended as follows ：

11 Remove this throw statement from this finally block.

explain ： stay finally Block the use of return、break、throw Wait can inhibit try or catch Any unhandled thrown in the block Throwable Communication of , It is amended as follows ：

12 Remove this return statement from this finally block

explain ： because finally Write the inside return At the time of statement , It will be covered try In the code block return. because finally It will certainly be carried out . Examples are as follows ：

The above code is modified to ：

13 A “NullPointerException” could be thrown; “pkList” is nullable here.

Add null value judgment , As shown below ：

14 Use try-with-resources or close this “ResultSet” in a “finally” clause.

It is amended as follows ：

Or refer to the following ：


Prompt that the resource is not closed , Need to be in finally Closing resources in , But turn off resources and put them in finally It is not standardized and has peculiar smell . So the recommended way to write it is to put the code that creates the resource flow in try() in , In this way, the system will automatically close resources , We don't need to write .close() Method , Pictured

15 Use “Arrays.toString(array)” instead.

It is amended as follows ：

Refer to the following

16 Save and re-use this “Random”.

explain ： This hint is that random numbers should be reused , Then the reference he gave was like this

17 Either re-interrupt this method or rethrow the “InterruptedException”.

It is amended as follows

18 Synchronize on a new “Object” instead.

It is amended as follows

19 Replace the call to “Thread.sleep(…)” with a call to “wait(…)”

explain ： If called when the current thread holds the lock Thread.sleep（…）, This can lead to performance and scalability problems , Even worse , Because the execution of the thread holding the lock is frozen . The best of monitor Object call wait（…） To temporarily release the lock and allow other threads to run . It is amended as follows ：

20 Use “BigDecimal.valueOf” instead

explain ： Due to the imprecision of floating point , You are unlikely to come from BigDecimal(double) Get the expected value from the constructor . It is amended as follows ：

21 Call “Optional#isPresent()” before accessing the value.

explain ：Optional value You can save values , You can also not save . Values in optional methods can be used get() Method access , But it throws one
If there is no value , be NoSuchElementException. To avoid abnormality , Should always call get() Previous call isPresent() Method .
in addition , Please pay attention to other methods , Such as orElse(…)、orElseGet(…) or orElseThrow(…), Can be used to specify how to handle empty optional objects .

It is amended as follows ：

22 Use try-with-resources or close this “PreparedStatement” in a “finally” clause.

Change it as follows ： Use try-with-resources grammar

Loophole

23 Make this “public static producer” field final

It is amended as follows ：

24 Lower the visibility of this setter or remove it altogether.

resolvent ： Remove... From the enumeration set Method

25 Make this “public static redisTemplate” field final

It is amended as follows ：

26 A “NullPointerException” could be thrown; “command” is nullable here.

Null pointer , Solution ： Judge first or instantiate first , Then access the properties or members .

27 Cast one of the operands of this multiplication operation to a “long”

explain ：int The number operation finally turns the result into long It is possible to overflow
Solution ： Convert to long Type budget

give an example ：
long bigNum = Integer.MAX_VALUE + 2; // Noncompliant. Yields -2147483647

Replace with
long bigNum = Integer.MAX_VALUE + 2L;

28 Make this member “protected”.

terms of settlement

29 Not enough arguments

The one above bug Very common in projects , All parameters are used new Object[]{} encapsulated . Especially from class File decompiled java The file format is the same . But if we want to eliminate bug If so, just use parameters directly , Do not use new Object[]{} encapsulation .

30 This branch can not be reached because the condition duplicates a previous condition in the same sequence of “if/else if” statements

if Two branches cannot be the same .

Just delete the duplicate .

31 Make this “public static st_soTimeout” field final

There's no good reason not to declare fields “final” In this case, declare the field “public” and “static”. Most of the time , This is an error sharing state between multiple objects . But in this way , Any object can do whatever it wants with the shared state , For example, set it to null .
solve

32 Make st_sendPort a static final constant or non-public and provide accessors if needed.

33 ‘PassWord’ detected in this expression, review this potentially hard-coded credential.