blocks|key|2909240|text|Double不是Integer，因此强制转换不起作用。请注意Double+类和double+原语之间的区别。还要注意，Double是一个Number，so+it+has+the+method+intValue，您可以使用它将值作为原语int获取。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|BOLD|entityRanges|data|2909241|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/6/docs/api/java/lang/Number.html#intValue%2528%2529^0|0|6|8|7|U|6|13|6|1N|6|1W|6|2O|8|39|3|11|1|1A|2|23|K|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]|$9|13|A|14|B|C]|$9|15|A|16|B|D]|$9|17|A|18|B|D]]|E|@$9|19|A|1A|1|1B]]|F|$]]|$1|G|3|-4|5|6|7|1C|8|@]|E|@]|F|$]]]|H|$I|$5|J|K|L|F|$M|N]]]]

A <code>Double</code> is not an <code>Integer</code>, so the cast won't work. Note the difference between the <code>Double</code> class and the <code>double</code> primitive. Also note that a <code>Double</code> is a <code>Number</code>, <a href="http://docs.oracle.com/javase/6/docs/api/java/lang/Number.html#intValue%28%29" rel="noreferrer">so it has the method</a> <code>intValue</code>, which you can use to get the value as a primitive <code>int</code>.

blocks|key|237749|text|您需要使用intValue()方法显式获取int值，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|237750|Double+d+=+5.25;
Integer+i+=+d.intValue();+//+i+becomes+5|code-block|syntax|javascript|237751|或|237752|double+d+=+5.25;
int+i+=+(int)+d;|237753|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You need to explicitly get the int value using method intValue() like this:

<pre><code>Double d = 5.25;
Integer i = d.intValue(); // i becomes 5
</code></pre>

Or 

<pre><code>double d = 5.25;
int i = (int) d;
</code></pre>

blocks|key|3123681|text|Double和Integer分别是double和int的Java原语的包装类。你可以在这两者之间进行转换，但是你会丢失浮点数。也就是说，5.4被强制转换为int将是5。如果你将它转换回，它将是5.0。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3123682|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|$]]

Double and Integer are wrapper classes for Java primitives for double and int respectively. You can cast between those, but you will lose the floating point. That is, 5.4 casted to an int will be 5. If you cast it back, it will be 5.0.

blocks|key|237764|text|如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|237765|Double+foo+=+123.456;
Integer+bar+=+foo.intValue();|code-block|syntax|javascript|237766|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|$]]

Like this: 

<pre><code>Double foo = 123.456;
Integer bar = foo.intValue();
</code></pre>

blocks|key|3123692|text|double+a+=+13.34;
int+b+=+(int)+a;

System.out.println(b);+//prints+13|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3123693|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>double a = 13.34;
int b = (int) a;

System.out.println(b); //prints 13
</code></pre>

blocks|key|241281|text|我认为有三种可能性。前两个截断了数字，最后一个舍入到最接近的整数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|241282|double+d+=+9.5;
int+i+=+(int)d;
//i+=+9

Double+D+=+9.5;
int+i+=+Integer.valueOf(D.intValue());
//i+=+9

double+d+=+9.5;
Long+L+=+Math.round(d);
int+i+=+Integer.valueOf(L.intValue());
//i+=+10|code-block|syntax|javascript|241283|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|$]]

I see three possibilities. The first two cut off the digits, the last one rounds to the nearest Integer.

<pre><code>double d = 9.5;
int i = (int)d;
//i = 9

Double D = 9.5;
int i = Integer.valueOf(D.intValue());
//i = 9

double d = 9.5;
Long L = Math.round(d);
int i = Integer.valueOf(L.intValue());
//i = 10
</code></pre>

blocks|key|2909312|text|Double+d+=+100.00;
Integer+i+=+d.intValue();|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2909313|还需要补充的是，它可以与自动装箱一起工作。|unstyled|2909314|否则，您将获得一个int+(原语)，然后可以从中获得一个Integer：|2909315|Integer+i+=+new+Integer(d.intValue());|2909316|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$B|C]]|$1|K|3|-4|5|F|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>Double d = 100.00;
Integer i = d.intValue();
</code></pre>

One should also add that it works with autoboxing.

Otherwise, you get an int (primitive) and then can get an Integer from there:

<pre><code>Integer i = new Integer(d.intValue());
</code></pre>

blocks|key|2909343|text|实际上，最简单的方法是使用intValue()。但是，这只返回整数部分；它不进行任何舍入。如果您希望Integer最接近双精度值，则需要执行以下操作：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2909344|Integer+integer+=+Integer.valueOf((int)+Math.round(myDouble)));|code-block|syntax|javascript|2909345|别忘了null大小写：|2909346|Integer+integer+=+myDouble+==+null+?+null+:+Integer.valueOf((int)+Math.round(myDouble)));|2909347|Math.round()相对优雅地处理了一些奇怪的情况，比如infinity和NaN。|2909348|entityMap^0|D|A|0|0|0|0|0|C|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|R|$]]

Indeed, the simplest way is to use <code>intValue()</code>. However, this merely returns the integer part; it does not do any rounding. If you want the Integer nearest to the Double value, you'll need to do this:

<pre><code>Integer integer = Integer.valueOf((int) Math.round(myDouble)));
</code></pre>

And don't forget the null case:

<pre><code>Integer integer = myDouble == null ? null : Integer.valueOf((int) Math.round(myDouble)));
</code></pre>

<code>Math.round()</code> handles odd duck cases, like infinity and NaN, with relative grace.

blocks|key|240261|text|我认为，如果不介绍陷阱并对其背后的进行推理，就不可能理解其他答案。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|240262|不能将Integer直接转换为Double对象。此外，Double和Integer是不可变的对象，因此您无法以任何方式修改它们。|CODE|240263|每个数值型类都有一个原语替代(Double+vs+double，Integer+vs+int，...)。请注意，这些原语以小写字符开头(例如int)。这告诉我们它们不是类/对象。这也意味着他们没有方法。相比之下，类(例如Integer)在这些原语周围的作用就像盒子/包装器，这使得像对象一样使用它们成为可能。|240264|策略：|240265|要将Double转换为Integer，您需要遵循以下策略：|240266|240267|将Double对象转换为基元double。(=将原始double转换为原始int。(=将基元int返回到Integer对象。(=+"boxing")|ordered-list-item|240268|240269|在代码中：|240270|//+starting+point
Double+myDouble+=+Double.valueOf(10.0);

//+step+1:+unboxing
double+dbl+=+myDouble.doubleValue();

//+step+2:+casting
int+intgr+=+(int)+dbl;

//+step+3:+boxing
Integer+val+=+Integer.valueOf(intgr);|code-block|syntax|javascript|240271|实际上，有一条捷径。您可以立即从Double直接取消装箱到原始int。这样，您就可以完全跳过步骤2。|240272|Double+myDouble+=+Double.valueOf(10.0);
Integer+val+=+Integer.valueOf(myDouble.intValue());+//+the+simple+way|240273|陷阱：|240274|然而，上面的代码中没有涵盖很多东西。上面的代码是not+null-safe。|240275|Double+myDouble+=+null;
Integer+val+=+Integer.valueOf(myDouble.intValue());+//+will+throw+a+NullPointerException

//+a+null-safe+solution:
Integer+val+=+(myDouble+==+null)?+null+:+Integer.valueOf(myDouble.intValue());|240276|现在，它可以很好地处理大多数值。但是，与Double相比，整数的范围(最小/最大值)非常小。最重要的是，doubles还可以保存整数不能保存的“特殊值”：|240277|未定义1/0=+%2Binfinity+|240278|-1/0+=+-infinity|unordered-list-item|240279|
|240280|0/0+=未定义(NaN)|240281|240282|因此，根据应用程序的不同，您可能希望添加一些筛选以避免令人讨厌的异常。|240283|然后，下一个缺点是舍入策略。默认情况下，Java将始终向下舍入。向下舍入在所有编程语言中都很有意义。基本上，Java只是丢弃了一些字节。在金融应用中，你肯定会想要使用半舍五入(例如：round(0.5)+=+1和round(0.4)+=+0)。|240284|//+null-safe+and+with+better+rounding
long+rounded+=+(myDouble+==+null)?+0L:+Math.round(myDouble.doubleValue());
Integer+val+=+Integer.valueOf(rounded);|240285|自动(取消)装箱|240286|你可能很想在本文中使用auto-(un)boxing，但我不会，如果你现在已经被卡住了，那么下面的例子也不会那么明显。如果您不了解自动(取消)装箱的内部工作原理，请不要使用它。|240287|Integer+val1+=+10;+//+works
Integer+val2+=+10.0;+//+doesn't+work

Double+val3+=+10;+//+doesn't+work
Double+val4+=+10.0;+//+works

Double+val5+=+null;+
double+val6+=+val5;+//+doesn't+work+(throws+a+NullPointerException)|240288|我想下面的内容应该不会让人感到惊讶。但是如果是这样的话，您可能需要阅读一些关于Java中的强制转换的文章。|240289|double+val7+=+(double)+10;+//+works
Double+val8+=+(Double)+Integer.valueOf(10);+//+doesn't+work
Integer+val9+=+(Integer)+9;+//+pure+nonsense|240290|首选valueOf：|240291|此外，不要尝试使用new+Integer()构造函数(正如其他一些答案所建议的那样)。valueOf()方法更好，因为它们使用缓存。使用这些方法是一个好习惯，因为它们会不时地为您节省一些内存。|240292|long+rounded+=+(myDouble+==+null)?+0L:+Math.round(myDouble.doubleValue());
Integer+val+=+new+Integer(rounded);+//+waste+of+memory|240293|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.oracle.com/javase/tutorial/java/data/autoboxing.html^0|9|8|0|3|7|F|6|R|6|Y|7|0|5|1|A|2|F|6|P|6|W|7|17|3|1Y|3|32|7|0|0|2|6|B|7|0|0|1|6|E|6|Q|6|11|3|1A|3|1G|7|0|0|0|0|G|6|V|3|0|0|0|O|E|0|0|K|6|0|0|0|0|0|0|0|2J|E|2Y|E|0|0|0|B|F|0|0|0|0|0|0|9|D|17|9|0|0^^$0|@$1|2|3|4|5|6|7|2G|8|@$9|2H|A|2I|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|2J|8|@$9|2K|A|2L|B|H]|$9|2M|A|2N|B|H]|$9|2O|A|2P|B|H]|$9|2Q|A|2R|B|H]]|D|@]|E|$]]|$1|I|3|J|5|6|7|2S|8|@$9|2T|A|2U|B|C]|$9|2V|A|2W|B|C]|$9|2X|A|2Y|B|H]|$9|2Z|A|30|B|H]|$9|31|A|32|B|H]|$9|33|A|34|B|H]|$9|35|A|36|B|H]|$9|37|A|38|B|H]]|D|@]|E|$]]|$1|K|3|L|5|6|7|39|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|3A|8|@$9|3B|A|3C|B|H]|$9|3D|A|3E|B|H]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|3F|8|@]|D|@]|E|$]]|$1|P|3|Q|5|R|7|3G|8|@$9|3H|A|3I|B|H]|$9|3J|A|3K|B|H]|$9|3L|A|3M|B|H]|$9|3N|A|3O|B|H]|$9|3P|A|3Q|B|H]|$9|3R|A|3S|B|H]]|D|@]|E|$]]|$1|S|3|-4|5|6|7|3T|8|@]|D|@]|E|$]]|$1|T|3|U|5|6|7|3U|8|@]|D|@]|E|$]]|$1|V|3|W|5|X|7|3V|8|@]|D|@]|E|$Y|Z]]|$1|10|3|11|5|6|7|3W|8|@$9|3X|A|3Y|B|H]|$9|3Z|A|40|B|H]]|D|@]|E|$]]|$1|12|3|13|5|X|7|41|8|@]|D|@]|E|$Y|Z]]|$1|14|3|15|5|6|7|42|8|@]|D|@]|E|$]]|$1|16|3|17|5|6|7|43|8|@$9|44|A|45|B|C]]|D|@]|E|$]]|$1|18|3|19|5|X|7|46|8|@]|D|@]|E|$Y|Z]]|$1|1A|3|1B|5|6|7|47|8|@$9|48|A|49|B|H]]|D|@]|E|$]]|$1|1C|3|1D|5|6|7|4A|8|@]|D|@]|E|$]]|$1|1E|3|1F|5|1G|7|4B|8|@]|D|@]|E|$]]|$1|1H|3|1I|5|6|7|4C|8|@]|D|@]|E|$]]|$1|1J|3|1K|5|1G|7|4D|8|@]|D|@]|E|$]]|$1|1L|3|-4|5|6|7|4E|8|@]|D|@]|E|$]]|$1|1M|3|1N|5|6|7|4F|8|@]|D|@]|E|$]]|$1|1O|3|1P|5|6|7|4G|8|@$9|4H|A|4I|B|H]|$9|4J|A|4K|B|H]]|D|@]|E|$]]|$1|1Q|3|1R|5|X|7|4L|8|@]|D|@]|E|$Y|Z]]|$1|1S|3|1T|5|6|7|4M|8|@]|D|@]|E|$]]|$1|1U|3|1V|5|6|7|4N|8|@]|D|@$9|4O|A|4P|1|4Q]]|E|$]]|$1|1W|3|1X|5|X|7|4R|8|@]|D|@]|E|$Y|Z]]|$1|1Y|3|1Z|5|6|7|4S|8|@]|D|@]|E|$]]|$1|20|3|21|5|X|7|4T|8|@]|D|@]|E|$Y|Z]]|$1|22|3|23|5|6|7|4U|8|@]|D|@]|E|$]]|$1|24|3|25|5|6|7|4V|8|@$9|4W|A|4X|B|H]|$9|4Y|A|4Z|B|H]]|D|@]|E|$]]|$1|26|3|27|5|X|7|50|8|@]|D|@]|E|$Y|Z]]|$1|28|3|-4|5|6|7|51|8|@]|D|@]|E|$]]]|29|$2A|$5|2B|2C|2D|E|$2E|2F]]]]

I think it's impossible to understand the other answers without covering the pitfalls and reasoning behind it.

You cannot directly cast an <code>Integer</code> to a <code>Double</code> object. Also <code>Double</code> and <code>Integer</code> are immutable objects, so you cannot modify them in any way. 

Each numeric class has a primitive alternative (<code>Double</code> vs <code>double</code>, <code>Integer</code> vs <code>int</code>, ...). Note that these primitives start with a lowercase character (e.g. <code>int</code>). That tells us that they aren't classes/objects. Which also means that they don't have methods. By contrast, the classes (e.g. <code>Integer</code>) act like boxes/wrappers around these primitives, which makes it possible to use them like objects.

<h1>Strategy:</h1>

To convert a <code>Double</code> to an <code>Integer</code> you would need to follow this strategy:

<ol>
<li>Convert the <code>Double</code> object to a primitive <code>double</code>. (= "unboxing")</li>
<li>Convert the primitive <code>double</code> to a primitive <code>int</code>. (= "casting")</li>
<li>Convert the primitive <code>int</code> back to an <code>Integer</code> object. (= "boxing")</li>
</ol>

<h1>In code:</h1>

<pre><code>// starting point
Double myDouble = Double.valueOf(10.0);

// step 1: unboxing
double dbl = myDouble.doubleValue();

// step 2: casting
int intgr = (int) dbl;

// step 3: boxing
Integer val = Integer.valueOf(intgr);
</code></pre>

Actually there is a shortcut. You can unbox immediately from a <code>Double</code> straight to a primitive <code>int</code>. That way, you can skip step 2 entirely.

<pre><code>Double myDouble = Double.valueOf(10.0);
Integer val = Integer.valueOf(myDouble.intValue()); // the simple way
</code></pre>

<h1>Pitfalls:</h1>

However, there are a lot of things that are not covered in the code above.
The code-above is not null-safe.

<pre><code>Double myDouble = null;
Integer val = Integer.valueOf(myDouble.intValue()); // will throw a NullPointerException

// a null-safe solution:
Integer val = (myDouble == null)? null : Integer.valueOf(myDouble.intValue());
</code></pre>

Now it works fine for most values. However integers have a very small range (min/max value) compared to a <code>Double</code>. On top of that, doubles can also hold "special values", that integers cannot:

<ul>
<li>1/0 = +infinity </li>
<li>-1/0 = -infinity</li>
<li>0/0 = undefined (NaN)</li>
</ul>

So, depending on the application, you may want to add some filtering to avoid nasty Exceptions.

Then, the next shortcoming is the rounding strategy. By default Java will always round down. Rounding down makes perfect sense in all programming languages. Basically Java is just throwing away some of the bytes. In financial applications you will surely want to use half-up rounding (e.g.: <code>round(0.5) = 1</code> and <code>round(0.4) = 0</code>).

<pre><code>// null-safe and with better rounding
long rounded = (myDouble == null)? 0L: Math.round(myDouble.doubleValue());
Integer val = Integer.valueOf(rounded);
</code></pre>

<h1>Auto-(un)boxing</h1>

You could be tempted to use <a href="https://docs.oracle.com/javase/tutorial/java/data/autoboxing.html" rel="noreferrer">auto-(un)boxing</a> in this, but I wouldn't. If you're already stuck now, then the next examples will not be that obvious neither. If you don't understand the inner workings of auto-(un)boxing then please don't use it.

<pre><code>Integer val1 = 10; // works
Integer val2 = 10.0; // doesn't work

Double val3 = 10; // doesn't work
Double val4 = 10.0; // works

Double val5 = null; 
double val6 = val5; // doesn't work (throws a NullPointerException)
</code></pre>

I guess the following shouldn't be a surprise. But if it is, then you may want to read some article about casting in Java.

<pre><code>double val7 = (double) 10; // works
Double val8 = (Double) Integer.valueOf(10); // doesn't work
Integer val9 = (Integer) 9; // pure nonsense
</code></pre>

<h1>Prefer valueOf:</h1>

Also, don't be tempted to use <code>new Integer()</code> constructor (as some other answers propose). The <code>valueOf()</code> methods are better because they use caching. It's a good habit to use these methods, because from time to time they will save you some memory.

<pre><code>long rounded = (myDouble == null)? 0L: Math.round(myDouble.doubleValue());
Integer val = new Integer(rounded); // waste of memory
</code></pre>

blocks|key|242929|text|简单地这样做……|type|unstyled|depth|inlineStyleRanges|entityRanges|data|242930|Double+d+=+13.5578;
int+i+=+d.intValue();
System.out.println(i);|code-block|syntax|javascript|242931|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|$]]

Simply do it this way...

<pre><code>Double d = 13.5578;
int i = d.intValue();
System.out.println(i);
</code></pre>

blocks|key|3123794|text|使用doubleNumber.intValue();方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3123795|entityMap^0|2|O|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

Use the <code>doubleNumber.intValue();</code> method.

blocks|key|240308|text|只需使用Double的intValue方法|type|unstyled|depth|inlineStyleRanges|entityRanges|data|240309|Double+initialValue+=+7.12;
int+finalValue+=+initialValue.intValue();|code-block|syntax|javascript|240310|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|$]]

Simply use the intValue method of Double

<pre><code>Double initialValue = 7.12;
int finalValue = initialValue.intValue();
</code></pre>

blocks|key|2909438|text|你可以通过使用“缩小或显式类型转换”，double→long→int来做到这一点。我希望它能起作用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2909439|double+d+=+100.04;
long+l+=+(long)d;+//+Explicit+type+casting+required
int+i+=+(int)l;++++//+Explicit+type+casting+required|code-block|syntax|javascript|2909440|PS:它会给出0，因为double有所有的十进制值，而左边没有任何值。在0.58的情况下，它会将其缩小到0。但对另一些人来说，它会产生魔力。|2909441|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You can do that by using "Narrowing or Explicit type conversion",
double → long → int. I hope it will work.

<pre><code>double d = 100.04;
long l = (long)d; // Explicit type casting required
int i = (int)l; // Explicit type casting required
</code></pre>

PS: It will give 0 as double has all the decimal values and nothing on the left side. In case of 0.58, it will narrow it down to 0. But for others it will do the magic.

blocks|key|2909454|text|在Double对象上调用intValue()。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2909455|entityMap^0|1|6|C|A|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

Call <code>intValue()</code> on your <code>Double</code> object.

blocks|key|240344|text|试试这个|type|unstyled|depth|inlineStyleRanges|entityRanges|data|240345|double+doubleValue+=+6.5;Double+doubleObj+=+new+Double(doubleValue);int+intResult+=+doubleObj.intValue();|code-block|syntax|javascript|240346|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|$]]

Try this one

<pre><code>double doubleValue = 6.5;Double doubleObj = new Double(doubleValue);int intResult = doubleObj.intValue();
</code></pre>

blocks|key|240348|text|这对我很有效。试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|240349|double+od+=+Double.parseDouble("1.15");
int+oi+=+(int)+od;|code-block|syntax|javascript|240350|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|$]]

It's worked for me. Try this:

<pre><code>double od = Double.parseDouble("1.15");
int oi = (int) od;
</code></pre>

blocks|key|241358|text|内存效率，因为它将共享已经创建的Double实例。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|241359|Double.valueOf(Math.floor(54644546464/60*60*24*365)).intValue()|code-block|syntax|javascript|241360|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|$]]

Memory efficient, as it will share the already created instance of Double.

<pre><code>Double.valueOf(Math.floor(54644546464/60*60*24*365)).intValue()
</code></pre>

blocks|key|242982|text|或者，可以先转换为原语double，然后转换为int，让它自动装箱为Integer。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|242983|Double+d+=+20.3;
Integer+i+=+(int)+(double)+d;+//20
//To+obtain+primitive:
int+i2+=+(int)+(double)+d;|code-block|syntax|javascript|242984|entityMap^0|B|6|N|3|Y|7|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|L|$]]

Alternatively, one can first cast to primitive <code>double</code>, then cast to <code>int</code>, letting it be autoboxed to <code>Integer</code>.
<pre><code>Double d = 20.3;
Integer i = (int) (double) d; //20
//To obtain primitive:
int i2 = (int) (double) d;
</code></pre>

blocks|key|240358|text|首先，你应该使用Double，而不是double。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|240359|示例|240360|int+intResult+=+newDoubleObj.intValue();|240361|entityMap^0|8|6|I|6|0|0|0|14|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|K|$]]

First thing you should use <code>Double</code> not <code>double</code>.
Example
<code>int intResult = newDoubleObj.intValue();</code>

Any way to cast <code>java.lang.Double</code> to <code>java.lang.Integer</code>? 

It throws an exception 

<blockquote>
 "java.lang.ClassCastException: java.lang.Double incompatible with java.lang.Integer"
</blockquote>

Cast Double to Integer in Java

Java

有没有办法将java.lang.Double转换为java.lang.Integer？它抛出一个异常 "java.lang.ClassCastException: java.lang.Double与java.lang.Integer不兼容“

问在Java中将Double转换为Integer
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