findBugs的一些功能说明

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我是靠谱客的博主开朗口红，最近开发中收集的这篇文章主要介绍findBugs的一些功能说明，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

1. equals比较不同的对象类型
Call to equals() comparing different types
This method calls equals(Object) on two references of different class types with no common subclasses. Therefore, the objects being compared are unlikely to be members of the same class at runtime (unless some application classes were not analyzed, or dynamic class loading can occur at runtime). According to the contract of equals(), objects of different classes should always compare as unequal; therefore, according to the contract defined by java.lang.Object.equals(Object), the result of this comparison will always be false at runtime.
说的是equals要比较相同的对象类型

2,可能产生空指针异常
Possible null pointer dereference
A reference value dereferenced here might be null at runtime. This may lead to a NullPointerException when the code is executed.

3.从未使用的本地变量
Dead store to local variable
This instruction assigns a value to a local variable, but the value is not read by any subsequent instruction. Often, this indicates an error, because the value computed is never used.
Note that Sun's javac compiler often generates dead stores for final local variables. Because FindBugs is a bytecode-based tool, there is no easy way to eliminate these false positives.

4.应该是一个静态内部类
Should be a static inner class

This class is an inner class, but does not use its embedded reference to the object which created it. This reference makes the instances of the class larger, and may keep the reference to the creator object alive longer than necessary. If possible, the class should be made static.

5.方法名称第一个字母小写
Method names should start with an lower case letter

Methods should be verbs, in mixed case with the first letter lowercase, with the first letter of each internal word capitalized.

6.用包装类的valueOf代替NEW
解释：因为用new Integer(int) 这样的方式会产生一个新的对象
而当编译时用valueOf则会被缓存，并且速度更快。
Method invokes inefficient Number constructor; use static valueOf instead

Using new Integer(int) is guaranteed to always result in a new object whereas Integer.valueOf(int) allows caching of values to be done by the compiler, class library, or JVM. Using of cached values avoids object allocation and the code will be faster.

7.Dead store to local variable 本地变量存储了闲置不用的对象
举例：
List accountCoList = new ArrayList();
我们为accountCoList新建了一个对象，但是程序的后面并没有使用这个这个新建对象。
建议改为：
List accountCoList = null;

8.Write to static field from instance method 向static字段中写入值
举例：
private static DBRBO dbrBO;
public final void refresh() {
        danskeBankBO = null;
        dbrBO = null;
        fileAndPathBO = null;
    }
建议改为：
去掉static。
9. Load of known null value 大体意思是加载了null的对象。
举例
        if (null == boList) {

            for (int i = 0; i < boList.size(); i++) {
                entityList.add(productBOToEntity(boList.get(i)));
            }
        }
10. Exception is caught when Exception is not thrown 这个意思比较好理解：就是catch了异常但是try里并没有抛出异常
11. Method ignores exceptional return value 没有对方法的异常返回值进行检查
12. Comparison of String objects using == or !=
This code compares java.lang.String objects for reference equality using the == or != operators.
Unless both strings are either constants in a source file, or have been interned using the String.intern() method,
the same string value may be represented by two different String objects. Consider using the equals(Object) method
instead.
从字面意思可以理解String对象进行比较的时候：只有两种情况可以使用== or !=的，这两种情况是；在源文件中是个常数或者是调用
String.intern()方法，使用String的规范化表示形式来进行比较,如果不是这两中情况的话推荐使用.equals(object)方式
13. Method names should start with a lower case letter 这个好理解方法名的第一个字母不能是大写
14. Non-transient non-serializable instance field in serializable class
This Serializable class defines a non-primitive instance field which is neither transient, Serializable,
or java.lang.Object, and does not appear to implement the Externalizable interface or the readObject()
and writeObject() methods.? Objects of this class will not be deserialized correctly if a non-Serializable object
   is stored in this field.
这个错误的意思是：在可序列化的类中存在不能序列化或者不能暂存的数据