New Patterns

[Xiaoven]

Eq: Covariant equals() method defined (EQ_SELF_NO_OBJECT)

This pattern may be partially implemented.

Description

This class defines a covariant version of equals(). To correctly override the equals() method in java.lang.Object, the parameter of equals() must have type java.lang.Object.

SP Implementation

spotbugs

• Condition 1: !hasEqualsObject && hasEqualsSelf
  • hasEqualsObject = true if method.isPublic() && "equals".equals(name) and the signature is (Ljava/lang/Object;)Z
  • hasEqualsSelf = true if method.isPublic() && "equals".equals(name) and sig.equals("(L" + getClassName() + ";)Z") (getClassName() should return current class name)
• Condition 2: !usesDefaultEquals
  • usesDefaultEquals = true if Values.DOTTED_JAVA_LANG_OBJECT.equals(whereEqual)
• Condition 3: "java.lang.Enum".equals(superclassName)
  • It should be another pattern EQ_DONT_DEFINE_EQUALS_FOR_ENUM

加上 online/local search 可进一步判断是不是 abstract class，进一步区分出 Eq: Abstract class defines covariant equals() method

[Xiaoven]

Co: Covariant compareTo() method defined (CO_SELF_NO_OBJECT)

Description

This class defines a covariant version of compareTo(). To correctly override the compareTo() method in the Comparable interface, the parameter of compareTo() must have type java.lang.Object.

SP Implementation

link

• Condition 1: !hasCompareToObject && !hasCompareToBridgeMethod && hasCompareToSelf
  • hasCompareToObject = true if "compareTo".equals(name) && sig.endsWith(")I") && !obj.isStatic() and "(Ljava/lang/Object;)I".equals(sig)
  • hasCompareToSelf = true if "compareTo".equals(name) && sig.endsWith(")I") && !obj.isStatic() and sig.equals("(L" + getClassName() + ";)I")
  • hasCompareToBridgeMethod = true if "compareTo".equals(name) && sig.endsWith(")I") && !obj.isStatic() and BCELUtil.isSynthetic(obj)
• Condition 2 : !extendsObject

Java synthetic methods

Any constructs introduced by the compiler that do not have a corresponding construct in the source code must be marked as synthetic, except for default constructors and the class initialization method.

Member.isSynthetic() returns true if and only if this member was introduced by the compiler.

The Java compiler must create synthetic methods on nested classes when their attributes specified with the private modifier are accessed by the enclosing class.

当存在内嵌class定义，而且需要在外包class和内嵌class之间访问对方的private修饰的属性的时候，java编译器必须创建synthetic method.
(请记住:对于java编译器而言，内部类也会被单独编译成一个class文件。那么原有代码中的相关属性可见性就难以维持，synthetic method也就是为了这个目的而生成的。生成的synthetic方法是包访问性的static方法.)

加上 online/local search 可进一步判断是不是 abstract class，进一步区分出 Co: Abstract class defines covariant compareTo() method

[Xiaoven]

RV: Negating the result of compareTo()/compare() (RV_NEGATING_RESULT_OF_COMPARETO)

This code negatives the return value of a compareTo or compare method. This is a questionable or bad programming practice, since if the return value is Integer.MIN_VALUE, negating the return value won't negate the sign of the result. You can achieve the same intended result by reversing the order of the operands rather than by negating the results.

检查没有中间变量那种

[Xiaoven]

ME: Enum field is public and mutable (ME_MUTABLE_ENUM_FIELD)

A mutable public field is defined inside a public enum, thus can be changed by malicious code or by accident from another package. Though mutable enum fields may be used for lazy initialization, it's a bad practice to expose them to the outer world. Consider declaring this field final and/or package-private.

SP Implementation

link

• classContext.getJavaClass().isEnum() && classContext.getJavaClass().isPublic()
• !field.isStatic() && !field.isFinal() && !field.isSynthetic() and field.isPublic()

Online/local search 判断 class 是否为 public enum，根据 public 关键词可以判断 是否为 field

例子

public enum Element {
    H("Hydrogen"),
    HE("Helium"),
    // ...
    NE("Neon");

    public String label;

    private Element(String label) {
        this.label = label;
    }
}

[Xiaoven]

Dm: Useless/vacuous call to EasyMock method (DMI_VACUOUS_CALL_TO_EASYMOCK_METHOD)

SP Implementation

https://github.com/spotbugs/spotbugs/blob/d9557689c2a752a833eedf4eb5f37ee712a9c84f/spotbugs/src/main/java/edu/umd/cs/findbugs/detect/DumbMethods.java#L850

Easymock API

检查的是特定的 static method invocation

EasyMock.verify();
EasyMock.replay();
EasyMock.reset();

[Xiaoven]

Dm: Futile attempt to change max pool size of ScheduledThreadPoolExecutor

https://github.com/spotbugs/spotbugs/blob/d9557689c2a752a833eedf4eb5f37ee712a9c84f/spotbugs/src/main/java/edu/umd/cs/findbugs/detect/DumbMethods.java#L209

检查是否调用 java/util/concurrent/ScheduledThreadPoolExecutor 对象的 setMaximumPoolSize 方法。方法名比较具体，是否可以实现一下？

[Xiaoven]

DMI: BigDecimal constructed from double that isn’t represented precisely (DMI_BIGDECIMAL_CONSTRUCTED_FROM_DOUBLE)

https://github.com/spotbugs/spotbugs/blob/d9557689c2a752a833eedf4eb5f37ee712a9c84f/spotbugs/src/main/java/edu/umd/cs/findbugs/detect/DumbMethods.java#L1399

检查像 new BigDecimal(0.1) 这样的

[Xiaoven]

RV: Bad attempt to compute absolute value of signed random integer (RV_ABSOLUTE_VALUE_OF_RANDOM_INT)

This code generates a random signed integer and then computes the absolute value of that random integer. If the number returned by the random number generator is Integer.MIN_VALUE, then the result will be negative as well (since Math.abs(Integer.MIN_VALUE) == Integer.MIN_VALUE). (Same problem arises for long values as well).

Spotbugs Implementation

https://github.com/spotbugs/spotbugs/blob/d9557689c2a752a833eedf4eb5f37ee712a9c84f/spotbugs/src/main/java/edu/umd/cs/findbugs/detect/DumbMethods.java#L904

Examples

int x = Math.abs(r.nextInt());

FP, spotbugs 有小小的data flow analysis. 我们可以用 local search 和 global search 看看有没有出现 "Integer.MIN_VALUE", 出现就不报了

    @DesireNoWarning("RV_ABSOLUTE_VALUE_OF_RANDOM_INT")
    public int testRandomInt() {
        int x = Math.abs(r.nextInt());
        if (x == Integer.MIN_VALUE)
            return 0;
        return x;
    }

RV: Bad attempt to compute absolute value of signed 32-bit hashcode (RV_ABSOLUTE_VALUE_OF_HASHCODE)

类似上一个

return Math.abs(key.hashCode());

[Xiaoven]

Nm: Apparent method/constructor confusion (NM_METHOD_CONSTRUCTOR_CONFUSION)

Spotbugs Implementation

https://github.com/spotbugs/spotbugs/blob/a6f9acb2932b54f5b70ea8bc206afb552321a222/spotbugs/src/main/java/edu/umd/cs/findbugs/detect/Naming.java#L181

检查 method name 是否和 file name 相同

[Xiaoven]

RV: Method ignores return value (RV_RETURN_VALUE_IGNORED)

The return value of this method should be checked. One common cause of this warning is to invoke a method on an immutable object, thinking that it updates the object. For example, in the following code fragment

Spotbugs Implementation

• CheckReturnValueAnnotation 定义的 CHECK_RETURN_VALUE_UNKNOWN, CHECK_RETURN_VALUE_HIGH, CHECK_RETURN_VALUE_MEDIUM, CHECK_RETURN_VALUE_LOW, CHECK_RETURN_VALUE_IGNORE 都跟这个 pattern 有关

• CheckReturnAnnotationDatabase 中，根据前面的 annotation 可以找到一堆要检查的 methods， 可以选取一些通过名字不容易认错的方法实现

• MethodReturnCheck 报warning的条件, 不太明白为什么前面为什么要出现 Const.NEW。建议多试试前面的 method lists，看看什么情况下会报。

[Xiaoven]

RV: Code checks for specific values returned by compareTo (RV_CHECK_COMPARETO_FOR_SPECIFIC_RETURN_VALUE)

This code invoked a compareTo or compare method, and checks to see if the return value is a specific value, such as 1 or -1. When invoking these methods, you should only check the sign of the result, not for any specific non-zero value. While many or most compareTo and compare methods only return -1, 0 or 1, some of them will return other values.

[Xiaoven]

DMI: Reversed method arguments (DMI_ARGUMENTS_WRONG_ORDER)

The arguments to this method call seem to be in the wrong order. For example, a call Preconditions.checkNotNull("message", message) has reserved arguments: the value to be checked is the first argument.

Spotbugs Implementation

link 只检查特定的 methods，看第二个参数是否是 string constant ？

[Xiaoven]

IJU: TestCase declares a bad suite method (IJU_BAD_SUITE_METHOD)

检查方法定义是否是以下之一

public static junit.framework.Test suite()

public static junit.framework.TestSuite suite()

如果用 online search 是否可以看 import junit.framework.Test和 import junit.framework.TestCase 信息？

IJU: TestCase implements a non-static suite method (IJU_SUITE_NOT_STATIC)

spotbugs
spotbugs 只看了是否是 TestCase 的子类，方法名和static