blocks|key|5094456|text|如果对整数值使用运算符/，则结果将被类型化为整数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|5094457|您必须将1或3强制为浮点值-尝试编写1.0/3而不是1/3。|5094458|entityMap^0|B|1|0|I|5|Q|3|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|R|8|@]|D|@]|E|$]]]|I|$]]

If you use the operator <code>/</code> on integer values, the result will be typed as an integer.

You will have to force either 1 or 3 to a floating point value - try writing <code>1.0/3</code> instead of <code>1/3</code>.

blocks|key|5094463|text|在后两种情况下，首先计算1/3，即0。然后将其转换为浮点数/双精度数。使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5094464|((float)1)/3|code-block|syntax|javascript|5094465|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In the last 2 cases you first compute 1/3, which is 0. Then you cast it to a float/double.
Use:

<pre><code>((float)1)/3
</code></pre>

blocks|key|5094478|text|首先，执行表达式1/3。这个表达式的意思是“1除以3的整数”。它的结果是整数0。然后将此结果(0)转换为双精度型(或浮点型)。当然，这也导致了0.0。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|5094479|必须将除法的一个操作数转换为双精度(或浮点数)，才能将其转换为双精度除法：|5094480|double+d+=+((double)+1)+/+3;|code-block|syntax|javascript|5094481|或者干脆写成|5094482|1.0+/+3|5094483|entityMap^0|8|3|12|1|1B|1|1Z|3|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|12|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|13|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|14|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|R|$]]

First, the expression <code>1/3</code> is executed. This expression means "integer division of 1 by 3". And its result is the integer <code>0</code>. Then this result (<code>0</code>) is cast to a double (or float). And of course it leads to <code>0.0</code>.

You must cast one of the operands of the division to a double (or float) to transform it into a double division:

<pre><code>double d = ((double) 1) / 3;
</code></pre>

or simply write

<pre><code>1.0 / 3
</code></pre>

blocks|key|5094510|text|整型转换为双精度型。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5094511|(1/3)的类型为int，因此答案将为0。|5094512|现在0被强制转换为双精度或浮点数，因此它变成了0.0|5094513|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

int is coverted into double.

(1/3) is of type int so answer will be 0.

Now 0 is casted to double or float so it has become 0.0

blocks|key|3310372|text|你需要转换操作数，而不是结果。这将产生您预期的输出：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3310373|System.out.println(((short)+1+/+(short)+3));
System.out.println((1+/+3));
System.out.println(((float)+1+/+(float)+3));
System.out.println(((double)+1+/+(double)+3));|code-block|syntax|javascript|3310374|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You need to cast the operands, not the result. This will yield the output you expected:

<pre><code>System.out.println(((short) 1 / (short) 3));
System.out.println((1 / 3));
System.out.println(((float) 1 / (float) 3));
System.out.println(((double) 1 / (double) 3));
</code></pre>

blocks|key|5094583|text|因为1/3放在括号中，所以它使用整数除法，然后强制转换为指定的类型。如果你使用1.0/3.0或(浮点数)1/3，它的计算结果将是.3333333。1和3是整型文字，因此除法的结果将被截断。要使用浮点数和双精度字面量，请在数字末尾添加一个f或d+(1.0f，1.0d)。强制转换会影响后面的值，因此如果您的值在括号中，它将对其求值，然后进行强制转换。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5094584|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Because you have the 1/3 in parentheses, it uses integer division then casts to the type specified. It would evaluate to .3333333 if you used 1.0/3.0 or (float)1/3. 1 and 3 are integer literals, so results from division will be truncated. To use float and double literals put an f or d at the end of the number (1.0f, 1.0d). Casting affects the value after it, so if your value is in parentheses, it will evaluate that, then make the cast.

this is my first post here and i like to thank all the people that can help me with this simple question: how the casting works in java?

I made this very simple class:

<pre><code>public class test {
 public static void main ( String[] args )
 {
 System.out.println((short)(1/3));
 System.out.println((int)(1/3));
 System.out.println((float)(1/3));
 System.out.println((double)(1/3));
 }
}
</code></pre>

and this piece of software gives me this output when executed ( official JDK 6 u26 on a 32 bit machine under linux )

<pre><code>0
0
0.0
0.0
</code></pre>

the problem, or the thing that i don't understand if you would, is that the last 2 results are 0.0, i was expecting something like 0.3333333, but apparently the cast works in another way: how?

thanks

PS
I'm not so familiar with the english language, if i made some errors i apologize for this

Understanding Casting in Java

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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这是我在这里的第一篇文章，我想感谢所有能帮助我回答这个简单问题的人: java中的造型是如何工作的？我做了一个非常简单的类：public class test {    public static void main ( String[] args )    {        System.out.println((s...

问了解Java中的类型转换
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问了解Java中的类型转换EN