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this specification are many allusions , such as one of them, because programmers easy to == mistakenly written as =
If you put in front of the constant 5 = i, will compile errors , so you can find this typo bug
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first written more stringent to ensure xxx is not null
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no any difference !
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no difference
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beans flavored with aniseed fennel word has several written
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no difference
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but I was head of the latter scolded - - said to be like the first to write tangled as it ~ ~ ~ depressed
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your head may not be familiar , you should not criticize
But since the curse , and you do not get angry , because he was not familiar
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encounter an unfamiliar java head no way
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I 've seen this before , it should be like the first One way to write , but I also do not forget the reason, heroes come popularize it.
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XXX What is a variable ? Or something else ?
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not the same thing ......
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did not make any difference.
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no difference
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1. java library to see how the code is written. Such as the String class ,
public static String valueOf(Object obj) {
return (obj == null) ? "null" : obj.toString();
}
2.http :/ / www.google.com.hk / codesearch, search for null! = lang: java, see everyone is how to write .
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lacks distinction , do not be too harsh
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variables must be of ~ ~
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tomorrow Results posted ~
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agree
some people when his head, but his stomach no goods, we had to take this stuff to scare people want to use this tree Granville
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no difference.
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this thought ! good landlord ah
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may be the norm , constants in the former, the variable in the post.
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prevent programmers write omission equals cause errors. null! = XX so less ! Will be given. The XX! = null less ! Would not be a
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this thought ! good landlord ah
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are not equal this method. .
this method are different.
you such wording . There should be no distinction between the bar. .
look at the following answer
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crap , i = 5 into if there is not an error ? !
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java in writing no difference between these two
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constant in the former, the variable in the post.
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from meaning there will be no difference from the norm in terms of programming , the first one was written in order to prevent write : null = xxx
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on the landlord to raise this issue , it should be possible Both spellings .
A situation like this:
object A.equals ("") is usually best written as "". equals (A), because A If null, easy throws NullPointerException
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in some cases, the latter returns a null pointer , you try , and the first one that does not report a null pointer error
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generally the case, but is used to determine equal "==" , the use of null == xxx, to prevent the == mistakenly written as an assignment =
As ! = no need to be so entirely designed ! The effect is the same, you really ***** head .
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first written wording better than the second , most of the actual item inside the code is written with the first one , the first than the second rigorous
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String sss = null
sss == null and null == sss no difference
obj.someMethod () == null and null == obj.someMethod () there is a difference
because obj is null null pointer exception thrown when the former , the latter will not
landlord know ?
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seems no different
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think about it, is that right ?
Do not fraught
if obj is null, no matter what the wording will be free pointer ; if obj is not null, will perform two written someMethod method, so if the first way to write empty pointer exception , then certainly the second wording will empty pointer exception , two written simply no difference
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fact, no difference is the first one can prevent you ! Forget about because you have forgotten ! a compilation error will not logical errors. So easy correction
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This is the difference
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c / c + + , there are conditions to prevent the judge erroneously written assignment function , java there is no difference
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null! = xxx and xxx! = null does not difference
"abc". equals (xxx) and xxx.equals ("abc") differentiated
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no difference between right
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only to prevent a typo put it like 23 F . Constant = variable , because the variable = constant correction seems to be forever really that much trouble ,
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we habitually use the first to write side , such an approach is not easy to go wrong when a value is null , may be judged often being given , it should be placed in front of the null , so even if a variable is null behind not being given in the specific practice if there is such a mistake can think about is not for this reason
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no difference
------ For reference only --------------------------------------- < br> on your head over some of the java Refbacks Division, Jean Hall and there were discussed the issue because in order to avoid major mistakes xxx is the variable with the former, it is not easy to make mistakes ; the compiler will complain even if error this error is mainly down " ! " No. but the second , then you forget the compiler will not complain if I do not know , oh so tell whether you can understand
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well, yes, that rigor , the first one is better
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this is mainly compile time error, for example, to determine whether x is equal to 1, there are two kinds of writing : x == 1 , 1 == x, but sometimes we wrong wrote x = 1,1 = x, which is the former wording of x = 1 is not being given , so it is difficult to find such an error , if it is behind a species , then the compiler will complain . So this is a matter of habit , usually develop 1 == x This style of writing is good.
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Oh, did not know there is this problem , really gain it.
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so. Afraid == mistakenly written = , such as
written
if(val==null){/*...*/}
if(val=null)//不会报错
However, if the null EDITORIAL will error :
if(null=val)
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"if (val = null) / / will not complain ."
do not know is not terrible, terrible is opinionated
Will you go to try to see an error, Lv eggs
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haha. That is certainly differentiated learning PHP and C + +, JS 's
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If you are a java programmer, both the wording did not make any difference , of course, if you are a C / C + + is another matter , the former written in C / C + + is more robust !
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use the first method if the wrong JDK can check it out. Better. Like sometimes if (x == 1) accidentally wrote if (x = 1) this is not an error. . Khan but also find their investigation . . . But written if (1 = x) the error because constants can not be directly assigned
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first one is the most formal wording
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roof 
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no difference , the head if you want to to how to how, head saying is not "wrong " drop
supplement , java is no difference , c / c + + is a difference drops
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this is the java will complain , but most other languages do not it, so encourage more rigorous way !
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both written in C # which is wrong it
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null! = xxx and xxx! = null differentiated it !
I have encountered such a problem
with xxx! = null runtime error
then replaced with null! = xxx is not being given .
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is to avoid null pointer chant ! Such a simple question . . Egg pain
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very responsible to tell you two ways for writing a null pointer exception will not
a null pointer exception was written by the equals method
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guess you were born leader is C + + , C + +, in order to avoid if being assigned to write null! = ; x, in java and c # can only exist if the Boolean type , there is no problem.
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sense ......
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prevent leakage write ! result in an error
Similarly xxx == null should be written as null == xxx
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top "if (val = null) / / will not complain " 51 F wrote java compiler used it
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Ah you put that contact to me, I can help you Masi Zhesi !
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wrong people reply Intuit more ......
do not do not play .....
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estimated that the brothers have not used eclipse ....
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in fact, it says if (val = null) does not complain is possible
Boolean b = null;
if (b = null);
so the future is not compiled in JDK1.5 error , but is a special case of the
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forehead , looks like I've also run into xxx! = null on the error , later changed to null! = xxx is not being given . Well , in order to rigorous proposals null! = Xxx it.
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71 F
you have not tried
Boolean b = null;
if (b = null);
this is right for you ?
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real time with the development of the first, second there may be a null pointer exception
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null! = XXX never come this way null pointer exception. Extreme Programming is also suggested wording
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this is a historical problem, now is not the problem
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+ +
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course is the first friends. . This can be very convenient error. .
can not be left as NULL values , so when you ! = Wrong when you can easily being given . . .
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do not use c or c + + to look upon java
if (a = 1) {
//这里是c/c++, 不会报错的, 而你的本意是想判断a是否等于1， 你应该写成a == 1。 为了让编译器提醒你,你写成1 == a 最好了, 如果你忘了写一个=号, 比如 1=a, 这时候是会报错的, 而a=1不会报错
}
if (a = 1) {
// 这里是java, 编译器直接报错了, 所以各位javaer, 在写"=="表达式的时候不要把变量写在前面了, OK? 要知道java是很强大的, 你写1 == a 和 a == 1没有任何区别, 这2个表达式哪一个少写等号直接报错了
}
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compile correct runtime exception (NPE)
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Most of the people like to write is parroting or c / c + + legacy wording
in java, xxx == null looked more comfortable , as well as " {" not a single new line
such wording in java, very alternative
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People are not saying java language . C, C + + Of course, you can write
if (i = 5)
it.
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constants can not be assigned , therefore null == xxx, if == mistakenly written = , then the compiler will pass ! Just a good habit to prevent obscure bug produces
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norms
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class A
{
public:
explicit A (int * a): m_a (NULL) {}
bool operator == (int * const a) const {
return (m_a == a);
}
private:
int * m_a;
};
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with the first good
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no difference
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order to prevent you from accidentally put "== " instead of " =" , such as:
If you write if (null = obj) it is certainly not pass compiled.
If you write if (obj = null) that can be compiled through . You can hardly find such errors .
But in the final analysis , just a habit.
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landlord is not to ask fennel beans have several written ?
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first wording is strictly prohibited ah good writing style
java inside if (p = null) ... is not being given
I decided to put on the left to avoid the constant low-level errors committed
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I only know a little bit of norms "". equals () try to make you their values on the back
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Ma Wan have to explain why you ?
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estimate is between JAVA and other language problems, but writing specifications or not, I have more vegetables, waiting for you.
if (val = null) in java is definitely wrong .
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js you say is right, I think you might be understood backwards - because if (i == 5) and if (i = 5) is not an error, it 's likely to occur typo bug, but if you use the first way to write , even if the programmer to 5 == i write 5 = i , and will generate an error , thus avoiding the occurrence of clerical errors .
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think Wan pressed the hand a little shiver is what results a =
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absolutely no difference
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order to prevent
xxx == null written in the wrong
xxx = null
! = what will be written in the wrong ?
Haha
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if (xx = null) will not complain ?
tested to answer , OK?
Here java
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no basic difference between friends do not worry about this
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