ide sonar代码审查问题总结

素颜马尾好姑娘i 2022-11-25 05:22 312阅读 0赞

格式：问题名字+问题出现的次数

[Resources should be closed][]2

资源未关闭，打开发现有两处用到的IO流没有关闭

*[Conditions should not unconditionally evaluate to "TRUE" or to "FALSE"][Conditions should not unconditionally evaluate to _TRUE_ or to _FALSE]1*

if/else判断里出现了重复判断，比如在if(a>10)的执行体里面又判断if(a<0)，而后者肯定不会是true

*[Exception handlers should preserve the original exception][]13*

处理异常的时候应该保留原始的异常情况，不要直接来个catch(Exception e)了事

*[Throwable.printStackTrace(...) should not be called][Throwable.printStackTrace_..._ should not be called]7*

不应该直接调用e.printStackTrace()，而是用Loggers来处理（就是打Log）。

Loggers的优势是：Users are able to easily retrieve the logs.

The format of log messages is uniform and allow users to browse the logs easily.

*[Instance methods should not write to "static" fields][Instance methods should not write to _static_ fields]6*

不要用实例方法改变静态成员，理想情况下，静态变量只通过同步的静态方法来改变

*["public static" fields should be constant][public static_ fields should be constant]1*

公共静态成员应该加上final，也就是public static final 一般不分家

*[Thread.run() and Runnable.run() should not be called directly][Thread.run_ and Runnable.run_ should not be called directly]1*

不应该直接调用Thread和Runnaale对象的run方法，直接调用run会使得run方法执行在当前线程，失去了开启新线程的意义。但有时候可能会这样做，下面有个例子。

*[Generic exceptions should never be thrown][]1*

不太理解，大意是说不要直接抛Error,RuntimeException/Throwable/Exception这样的通用的异常。我的具体应用是：throw new Error("Error copying database")，给出的建议是：Define and throw a dedicated exception instead of using a generic one（定义并抛出一个专用的异常来代替一个通用的异常）

*[Class variable fields should not have public accessibility][]64*

类变量不要设置为public，而是设为private，再提供get和set方法。

*[Sections of code should not be "commented out"][Sections of code should not be _commented out]30*

不要再注释中出现大量的代码段，会使代码可读性变差

*[Package declaration should match source file directory][]19*

这个没理解，包的声明应该与源文件目录匹配。

*[Utility classes should not have public constructors][]16*

工具类不应该有公共的构造器，也就是说至少要有一个private的构造器，如果没有，默认的构造器是public的。

*[The diamond operator ("<>") should be used][The diamond operator _ should be used]12*

在定义集合的时候，等号右边的<>内不需要再写上元素类型，直接空着就行。

*[Lambdas and anonymous classes should not have too many lines][]9*

*[Lambdas][Lambdas and anonymous classes should not have too many lines]表达式和匿名内部类不要写太多行，一般最多写20行。*

*[Anonymous inner classes containing only one method should become lambdas][]8*

只包含一个方法的匿名内部类应该写成*[Lambdas][Lambdas and anonymous classes should not have too many lines]表达式的形式，增强代码可读性*

*[Try-with-resources should be used][]8*

用Try-with-resources的形式取代try/catch/finally的形式，这个有待于以后学习。

*[Methods should not be empty][]7*

*不要写空方法，除非这种情况：An abstract class may have empty methods, in order to provide default implementations for child classes.*

*[Source files should not have any duplicated blocks][]7*

源文件中不要出现任何重复的代码段或行或字符串等。没理解。

*["switch case" clauses should not have too many lines][switch case_ clauses should not have too many lines]6*

*["switch case" ][switch case_ clauses should not have too many lines]每个case里面的代码不要太长，太长的话可以考虑写个方法代替，主要是为了增强代码可读性*

*[Nested blocks of code should not be left empty][]6*

嵌套代码块不要是空的，比如 if( a > 0 ) \{  doSomething()  \} else \{ \}，这时候应该把后面的else\{\}去掉。

*[Methods should not be too complex][]6*

方法不要太复杂，否则难以理解和维护。

*[Unused private fields should be removed][]5*

没有使用的private的成员变量应该移除掉。

*[Dead stores should be removed][]5*

没有用到的本地变量或其他死存储应该移除掉，也就是写方法的时候，定义的变量如果后来发现根本用不到，要记得删掉那行代码。

*["switch" statements should end with a "default" clause][switch_ statements should end with a _default_ clause]4*

switch语句应该以default结束，这是一种defensive programming思想

*[Unused method parameters should be removed][]4*

没有用到的方法参数应该移除掉

*[Control flow statements "if", "for", "while", "switch" and "try" should not be nested too deeply][Control flow statements _if_ _for_ _while_ _switch_ and _try_ should not be nested too deeply]4*

*if /for/while/try这样的嵌套不要太复杂*

*[Useless parentheses around expressions should be removed to prevent any misunderstanding][]3*

没有意义的括号不要随便加，以免造成误解，比如"="两边对象类型是相同的，就不要强转。

*["for" loop stop conditions should be invariant][for_ loop stop conditions should be invariant]3*

for循环的结果条件不能是变量，而应该是常量

*["static" members should be accessed statically][static_ members should be accessed statically]2*

static成员是与类、静态方法相联系的。

*[Catches should be combined][]2*

具体参考下面的18，我还没理解

*[Primitives should not be boxed just for "String" conversion][Primitives should not be boxed just for _String_ conversion]2*

不要使用 4+" "这样的方式将int值转变为字符串，而是使用 Integer.toString(4)这样的方式。

就像Integer.parseInt("我是字符串")这样，不要偷懒。

*[Classes should not be empty][]2*

不要写空类

*[Unused local variables should be removed][]2*

没有用到的本地变量要删掉

*["entrySet()" should be iterated when both the key and value are needed][entrySet_ should be iterated when both the key and value are needed]2*

直接看英文更直接：When only the keys from a map are needed in a loop, iterating the keySet makes sense. But when both the key and the value are needed, it's more efficient to iterate theentrySet, which will give access to both the key and value, instead.

也就是说，如果只需要Map的Key，那么直接iterate这个Map的keySet就可以了，但是如果Key和value都需要，就iterate这个Map。具体看下面的19.

*[Method parameters, caught exceptions and foreach variables should not be reassigned][Method parameters_ caught exceptions and foreach variables should not be reassigned]2*

方法参数/捕获的异常/*foreach的变量不应该被重新赋值。*

*[Collection.isEmpty() should be used to test for emptiness][Collection.isEmpty_ should be used to test for emptiness]2*

当判断集合是否为空的时候，不要使用if (myCollection.size() == 0) 这样的方式，而是使用if (myCollection.isEmpty()这样的方式，后者性能更高。

*[Standard outputs should not be used directly to log anything][]2*

标准输出不直接打印任何东西，也就是打log的时候，不要使用System.out.println("My Message")这样的方式，而是使用logger.log("My Message")这种方式。

*[Generic wildcard types should not be used in return parameters][]1*

通配符不应该出现在返回声明中。比如这句：List <? extends Animal>getAnimals()\{...\}， 我们无法知道“是否可以把a Dog, a Cat 等加进去”，等之后用到这个方法的时候，我们没必要去考虑这种问题（前面引号里面的）。

*[Synchronized classes Vector, Hashtable, Stack and StringBuffer should not be used][Synchronized classes Vector_ Hashtable_ Stack and StringBuffer should not be used]1*

不要使用同步的Vector/*HashTable/Stack/StringBuffer等。在早期，出于线程安全问题考虑，java API 提供了这些类。但是同步会极大影响性能，即使是在同一个线程中使用他们。*

通常可以这样取代：

ArrayList  or  LinkedList   instead of  Vector

Deque  instead of  Stack

HashMap  instead of  Hashtable

StringBuilder  instead of  StringBuffer

[Exit methods should not be called][]

尽量不要调用system.exit()方法。

*[Local Variables should not be declared and then immediately returned or thrown][]7*

本地变量如果赋值之后直接return了，那就直接return本地变量的赋值语句。

*[Field names should comply with a naming convention][]6*

命名要规范

*[Local variable and method parameter names should comply with a naming convention][]6*

命名要规范

*[String literals should not be duplicated][]5*

字符串不应该重复，如果多次用到同一字符串，建议将该字符串定义为字符串常量，再引用。

*[Return of boolean expressions should not be wrapped into an "if-then-else" statement][Return of boolean expressions should not be wrapped into an _if-then-else_ statement]3*

不要写if (  a > 4  ) \{  return false  \} else \{ return true \}这样的代码，直接写return a > 4。

*[Static non-final field names should comply with a naming convention][]2*

命名要规范

*[Modifiers should be declared in the correct order][]2*

修饰符等要按约定俗成的顺序书写 ，例如，写成public static 而不是static public

*[The members of an interface declaration or class should appear in a pre-defined order][]2*

与前面的一个问题类似，根据Oracle定义的Java代码规范中，不同代码的出现位置应该如下所示：

class and instance variables--Constructors--Methods

*[Array designators "\[\]" should be on the type, not the variable][Array designators _ should be on the type_ not the variable]2*

数组的括号要写在类型后面，而不是变量后面，例如 int\[\] a 而不是int a\[\]

*[Multiple variables should not be declared on the same line][]1*

不要在同一行定义多个变量

*["switch" statements should have at least 3 "case" clauses][switch_ statements should have at least 3 _case_ clauses]1*

当至少有3种或者3种以上的情况时，才考虑用switch，否则用if/else的形式。

*[Overriding methods should do more than simply call the same method in the super class][]1*

既然在子类中重写了父类的某个方法，那就再这个方法中做些与父类方法不同的事情，否则没必要重写。

*[Statements should be on separate lines][]1*

不要把这样的代码写在同一行：if(someCondition)    doSomething()；而是应该写成下面的形式

if(someCondition) \{

doSomething()

*[Method names should comply with a naming convention][]1*

命名要规范

[Resources should be closed]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS2095&rule_sev=BLOCKER
[Conditions should not unconditionally evaluate to _TRUE_ or to _FALSE]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS2583&rule_sev=BLOCKER
[Exception handlers should preserve the original exception]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1166&rule_sev=CRITICAL
[Throwable.printStackTrace_..._ should not be called]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1148&rule_sev=CRITICAL
[Instance methods should not write to _static_ fields]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS2696&rule_sev=CRITICAL
[public static_ fields should be constant]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1444&rule_sev=CRITICAL
[Thread.run_ and Runnable.run_ should not be called directly]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1217&rule_sev=CRITICAL
[Generic exceptions should never be thrown]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS00112&rule_sev=CRITICAL
[Class variable fields should not have public accessibility]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AClassVariableVisibilityCheck&rule_sev=MAJOR
[Sections of code should not be _commented out]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3ACommentedOutCodeLine&rule_sev=MAJOR
[Package declaration should match source file directory]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1598&rule_sev=MAJOR
[Utility classes should not have public constructors]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1118&rule_sev=MAJOR
[The diamond operator _ should be used]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS2293&rule_sev=MAJOR
[Lambdas and anonymous classes should not have too many lines]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1188&rule_sev=MAJOR
[Anonymous inner classes containing only one method should become lambdas]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1604&rule_sev=MAJOR
[Try-with-resources should be used]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS2093&rule_sev=MAJOR
[Methods should not be empty]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1186&rule_sev=MAJOR
[Source files should not have any duplicated blocks]: http://sonar.oschina.net/drilldown/issues/59054?&rule=common-java%3ADuplicatedBlocks&rule_sev=MAJOR
[switch case_ clauses should not have too many lines]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1151&rule_sev=MAJOR
[Nested blocks of code should not be left empty]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS00108&rule_sev=MAJOR
[Methods should not be too complex]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AMethodCyclomaticComplexity&rule_sev=MAJOR
[Unused private fields should be removed]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1068&rule_sev=MAJOR
[Dead stores should be removed]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1854&rule_sev=MAJOR
[switch_ statements should end with a _default_ clause]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3ASwitchLastCaseIsDefaultCheck&rule_sev=MAJOR
[Unused method parameters should be removed]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1172&rule_sev=MAJOR
[Control flow statements _if_ _for_ _while_ _switch_ and _try_ should not be nested too deeply]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS134&rule_sev=MAJOR
[Useless parentheses around expressions should be removed to prevent any misunderstanding]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AUselessParenthesesCheck&rule_sev=MAJOR
[for_ loop stop conditions should be invariant]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AForLoopCounterChangedCheck&rule_sev=MAJOR
[static_ members should be accessed statically]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS2209&rule_sev=MAJOR
[Catches should be combined]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS2147&rule_sev=MAJOR
[Primitives should not be boxed just for _String_ conversion]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS2131&rule_sev=MAJOR
[Classes should not be empty]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS2094&rule_sev=MAJOR
[Unused local variables should be removed]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1481&rule_sev=MAJOR
[entrySet_ should be iterated when both the key and value are needed]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS2864&rule_sev=MAJOR
[Method parameters_ caught exceptions and foreach variables should not be reassigned]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1226&rule_sev=MAJOR
[Collection.isEmpty_ should be used to test for emptiness]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1155&rule_sev=MAJOR
[Standard outputs should not be used directly to log anything]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS106&rule_sev=MAJOR
[Generic wildcard types should not be used in return parameters]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1452&rule_sev=MAJOR
[Synchronized classes Vector_ Hashtable_ Stack and StringBuffer should not be used]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1149&rule_sev=MAJOR
[Exit methods should not be called]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1147&rule_sev=MAJOR
[Local Variables should not be declared and then immediately returned or thrown]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1488&rule_sev=MINOR
[Field names should comply with a naming convention]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS00116&rule_sev=MINOR
[Local variable and method parameter names should comply with a naming convention]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS00117&rule_sev=MINOR
[String literals should not be duplicated]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1192&rule_sev=MINOR
[Return of boolean expressions should not be wrapped into an _if-then-else_ statement]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1126&rule_sev=MINOR
[Static non-final field names should comply with a naming convention]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS3008&rule_sev=MINOR
[Modifiers should be declared in the correct order]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AModifiersOrderCheck&rule_sev=MINOR
[The members of an interface declaration or class should appear in a pre-defined order]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1213&rule_sev=MINOR
[Array designators _ should be on the type_ not the variable]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1197&rule_sev=MINOR
[Multiple variables should not be declared on the same line]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1659&rule_sev=MINOR
[switch_ statements should have at least 3 _case_ clauses]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1301&rule_sev=MINOR
[Overriding methods should do more than simply call the same method in the super class]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS1185&rule_sev=MINOR
[Statements should be on separate lines]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS00122&rule_sev=MINOR
[Method names should comply with a naming convention]: http://sonar.oschina.net/drilldown/issues/59054?&rule=squid%3AS00100&rule_sev=MINOR