Question

该法典:

Integer ints[] = new Integer[]{ 1 ,  2 ,  3 };

只将胶卷中的罚款汇编成册,但javac(两种版本1.6.0_27和1.7.0)有以下错误:

BoxTest.java:4: incompatible types
found   : char
required: java.lang.Integer
               Integer ints[] = new Integer[]{ 1 ,  2 ,  3 };

BoxTest.java:4: incompatible types

为什么?

我假定它有某种编造旗,但挖掘出的粗金刚.并非直截了当。

Answer 1

javac不是这样做的,而是自动投放。在<代码>javac上,该编码汇编如下:

Integer ints[] = new Integer[] { (int)  1 , (int)  2 , (int)  3  };

只有一个<代码>Integer,另一个在javac上,I ve在进行以下明确编辑:

Integer a = (int)  1 ;

但这里我发现的情况。利用.Eclipse JDT batch codificationer ,从指挥线上运行,即使没有 cast:

$ java -jar org.eclipse.jdt.core_3.7.1.v_B76_R37x.jar -classpath rt.jar 
  -1.6 Appo.java

I ve look at the javac,我认为没有任何办法改变这种行为。

我现在想推断,差异是由这一事实造成的。内部没有使用<代码>javac,但联合执行监督委员会汇编者<>。

Answer 2

如stivlo所指出的,Eclipse JDT汇编者 silent默地对待这种守则:

Integer refI = Integer.valueOf((int) a );

但是,Java语言规格在(着重部分):

Assignment conversion occurs when the value of an expression is assigned (§15.26) to a variable: the type of the expression must be converted to the type of the variable. Assignment contexts allow the use of one of the following:
* an identity conversion (§5.1.1)
* a widening primitive conversion (§5.1.2)
* a widening reference conversion (§5.1.5)
* a boxing conversion (§5.1.7) optionally followed by a widening reference conversion
* an unboxing conversion (§5.1.8) optionally followed by a widening primitive conversion.

<代码>(int) a 的表示是第一次转换,Integer. ValueOf(int)是第二次转换。 <代码>javac汇编者仅允许一次转换即可执行规则。

So it seems, you have found a bug in the Eclipse JDT compiler.

Answer 3

I found a lot of confusion on this thread on how Eclipse compiles Java code. Here s the deal - Eclipse uses its "own" JDT compiler, which has nothing to do with either Sun or Sun s(now Oracle s) javac compiler. It is an independently developed compiler, licensed under EPL, and follows the JLS, just as javac does. So whatever does/does not compile with javac, does/does not compile with Eclipse JDT.

That said, the problem reported here looks like a bug in the Eclipse compiler. https://bugs.eclipse.org/bugs/show_bug.cgi?id=362279

Answer 4

Window -> Preference -> Compiler -> Errors/Warning -> Potential programming problems -> Boxing and unboxing conversions; set the value to Error

Answer 5

表面上看,来源的国旗被排在 Java的汽车前盒式上? 例如

javac - 来源1.4

Answer 6

实际上,Eclipse IDE利用Java @Suppress Warnings:

javac的道德等同选择是:xxx:

ADDENDUM:

Eclipse使用了标准JDK,其中javac是其中的一部分。

部分差异可通过内部使用Eclipse(有时称为“pragmas”)来说明,例如@sSuppress Warnings。

然而,MAIN的差异是,Eclipse使用JDT图书馆,这些图书馆是可起诉的。

在这里进行出色的讨论:

JDT More correct than Javac

希望。 PSM

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