blocks|key|1072695|text|对于较小的值，强制转换就足够了：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1072696|long+l+=+42;
int+i+=+(int)+l;|code-block|syntax|javascript|1072697|但是，与int相比，long可以容纳更多的信息，因此在一般情况下，不可能完美地从long转换为int。如果long包含的数字小于或等于Integer.MAX_VALUE，则可以通过强制转换进行转换，而不会丢失任何信息。|offset|length|style|CODE|1072698|例如，以下示例代码：|1072699|System.out.println(+"largest+long+is+"+%2B+Long.MAX_VALUE+);
System.out.println(+"largest+int+is+"+%2B+Integer.MAX_VALUE+);

long+x+=+(long)Integer.MAX_VALUE;
x%2B%2B;
System.out.println("long+x="+%2B+x);

int+y+=+(int)+x;
System.out.println("int+y="+%2B+y);|1072700|在我的机器上生成以下输出：|1072701|largest+long+is+9223372036854775807
largest+int+is+2147483647
long+x=2147483648
int+y=-2147483648|1072702|请注意y上的负号。因为x持有的值比Integer.MAX_VALUE大1，所以int+y无法持有它。在这种情况下，它绕到了负数。|1072703|如果你想自己处理这个案例，你可以这样做：|1072704|if+(+x+>+(long)Integer.MAX_VALUE+)+{
++++//+x+is+too+big+to+convert,+throw+an+exception+or+something+useful
}
else+{
++++y+=+(int)x;
}|1072705|所有这些都假设是正数。对于负数，请使用MIN_VALUE而不是MAX_VALUE。|1072706|entityMap^0|0|0|4|3|A|4|14|4|1B|3|1H|4|1V|H|0|0|0|0|0|3|1|B|1|H|H|13|5|0|0|0|J|9|V|9|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|16|8|@$I|17|J|18|K|L]|$I|19|J|1A|K|L]|$I|1B|J|1C|K|L]|$I|1D|J|1E|K|L]|$I|1F|J|1G|K|L]|$I|1H|J|1I|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|1J|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|1K|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|1L|8|@]|9|@]|A|$]]|$1|S|3|T|5|D|7|1M|8|@]|9|@]|A|$E|F]]|$1|U|3|V|5|6|7|1N|8|@$I|1O|J|1P|K|L]|$I|1Q|J|1R|K|L]|$I|1S|J|1T|K|L]|$I|1U|J|1V|K|L]]|9|@]|A|$]]|$1|W|3|X|5|6|7|1W|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|D|7|1X|8|@]|9|@]|A|$E|F]]|$1|10|3|11|5|6|7|1Y|8|@$I|1Z|J|20|K|L]|$I|21|J|22|K|L]]|9|@]|A|$]]|$1|12|3|-4|5|6|7|23|8|@]|9|@]|A|$]]]|13|$]]

For small values, casting is enough:
<pre><code>long l = 42;
int i = (int) l;
</code></pre>
However, a <code>long</code> can hold more information than an <code>int</code>, so it's not possible to perfectly convert from <code>long</code> to <code>int</code>, in the general case. If the <code>long</code> holds a number less than or equal to <code>Integer.MAX_VALUE</code> you can convert it by casting without losing any information.
For example, the following sample code:
<pre><code>System.out.println( &quot;largest long is &quot; + Long.MAX_VALUE );
System.out.println( &quot;largest int is &quot; + Integer.MAX_VALUE );

long x = (long)Integer.MAX_VALUE;
x++;
System.out.println(&quot;long x=&quot; + x);

int y = (int) x;
System.out.println(&quot;int y=&quot; + y);
</code></pre>
produces the following output on my machine:
<pre><code>largest long is 9223372036854775807
largest int is 2147483647
long x=2147483648
int y=-2147483648
</code></pre>
Notice the negative sign on <code>y</code>. Because <code>x</code> held a value one larger than <code>Integer.MAX_VALUE</code>, <code>int y</code> was unable to hold it. In this case, it wrapped around to the negative numbers.
If you wanted to handle this case yourself, you might do something like:
<pre><code>if ( x &gt; (long)Integer.MAX_VALUE ) {
 // x is too big to convert, throw an exception or something useful
}
else {
 y = (int)x;
}
</code></pre>
All of this assumes positive numbers. For negative numbers, use <code>MIN_VALUE</code> instead of <code>MAX_VALUE</code>.

blocks|key|1072851|text|如果使用Guava+library，可以使用Ints.checkedCast(long)和Ints.saturatedCast(long)方法将long转换为int。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1072852|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/google/guava|1|https://google.github.io/guava/releases/19.0/api/docs/com/google/common/primitives/Ints.html#checkedCast(long)|2|https://google.github.io/guava/releases/19.0/api/docs/com/google/common/primitives/Ints.html#saturatedCast(long)^0|M|M|19|O|20|4|27|3|4|D|0|M|M|1|19|O|2|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@$9|10|A|11|1|12]|$9|13|A|14|1|15]|$9|16|A|17|1|18]]|E|$]]|$1|F|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]|N|$5|I|J|K|E|$L|O]]|P|$5|I|J|K|E|$L|Q]]]]

If using <a href="https://github.com/google/guava" rel="noreferrer">Guava library</a>, there are methods <a href="https://google.github.io/guava/releases/19.0/api/docs/com/google/common/primitives/Ints.html#checkedCast(long)" rel="noreferrer"><code>Ints.checkedCast(long)</code></a> and <a href="https://google.github.io/guava/releases/19.0/api/docs/com/google/common/primitives/Ints.html#saturatedCast(long)" rel="noreferrer"><code>Ints.saturatedCast(long)</code></a> for converting <code>long</code> to <code>int</code>.

blocks|key|858067|text|long+x+=+3;
int+y+=+(int)+x;|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|858068|但是假设long可以表示为int，那么您知道这两者之间的区别吗？|unstyled|offset|length|style|CODE|858069|entityMap^0|0|4|4|D|3|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@$G|O|H|P|I|J]|$G|Q|H|R|I|J]]|9|@]|A|$]]|$1|K|3|-4|5|F|7|S|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>long x = 3;
int y = (int) x;
</code></pre>

but that assumes that the <code>long</code> can be represented as an <code>int</code>, you do know the difference between the two?

blocks|key|1072818|text|您可以使用Long包装器代替long原语并调用|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1072819|Long.intValue()|code-block|syntax|javascript|1072820|Java7+intValue()+docs|1072821|它相应地舍入/截断long值以适合int。|1072822|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/7/docs/api/java/lang/Long.html#intValue()^0|5|4|E|4|0|0|0|L|0|0|9|4|H|3|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|D|@$9|13|A|14|1|15]]|E|$]]|$1|M|3|N|5|6|7|16|8|@$9|17|A|18|B|C]|$9|19|A|1A|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

You can use the <code>Long</code> wrapper instead of <code>long</code> primitive and call 

<pre><code>Long.intValue()
</code></pre>

<a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Long.html#intValue()" rel="noreferrer">Java7 intValue() docs</a>

It rounds/truncate the <code>long</code> value accordingly to fit in an <code>int</code>.

blocks|key|1072968|text|如果直接转换显示错误，可以这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1072969|Long+id+=+100;
int+int_id+=+(int)+(id+%25+100000);|code-block|syntax|javascript|1072970|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|$]]

If direct casting shows error you can do it like this:

<pre><code>Long id = 100;
int int_id = (int) (id % 100000);
</code></pre>

blocks|key|1072780|text|在Java中，long是一个有符号的64位数字，这意味着您可以存储介于-9,223,372,036,854,775,808和9,223,372,036,854,775,807+(包括这两个数字)之间的数字。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1072781|另一方面，int是有符号的32位数字，这意味着您可以存储介于-2,147,483,648和2,147,483,647+(包括-2,147,483,647)之间的数字。|1072782|因此，如果您的long超出了int所允许的值，您将不会得到有价值的转换。|1072783|有关原始Java类型大小的详细信息，请参阅：|1072784|http://download.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html|offset|length|1072785|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|0|0|23|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|V|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|W|8|@]|9|@$J|X|K|Y|1|Z]]|A|$]]|$1|L|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|M|$N|$5|O|P|Q|A|$R|I]]]]

In Java, a long is a signed 64 bits number, which means you can store numbers between -9,223,372,036,854,775,808 and 9,223,372,036,854,775,807 (inclusive).

A int, on the other hand, is signed 32 bits number, which means you can store number between -2,147,483,648 and 2,147,483,647 (inclusive).

So if your long is outside of the values permitted for an int, you will not get a valuable conversion.

Details about sizes of primitive Java types here:

<a href="http://download.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html" rel="nofollow">http://download.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html</a>

blocks|key|1073100|text|最短、最安全、最简单的解决方案是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1073101|long+myValue=...;
int+asInt+=+Long.valueOf(myValue).intValue();|code-block|syntax|javascript|1073102|请注意，Long.valueOf的行为如下：|offset|length|style|CODE|1073103|使用以下代码：|1073104|System.out.println("Long+max:+"+%2B+Long.MAX_VALUE);
System.out.println("Int+max:+"+%2B+Integer.MAX_VALUE);++++++++
long+maxIntValue+=+Integer.MAX_VALUE;
System.out.println("Long+maxIntValue+to+int:+"+%2B+Long.valueOf(maxIntValue).intValue());
long+maxIntValuePlusOne+=+Integer.MAX_VALUE+%2B+1;
System.out.println("Long+maxIntValuePlusOne+to+int:+"+%2B+Long.valueOf(maxIntValuePlusOne).intValue());
System.out.println("Long+max+to+int:+"+%2B+Long.valueOf(Long.MAX_VALUE).intValue());|1073105|结果为：|1073106|Long+max:+9223372036854775807
Int+max:+2147483647
Long+max+to+int:+-1
Long+maxIntValue+to+int:+2147483647
Long+maxIntValuePlusOne+to+int:+-2147483648|1073107|entityMap^0|0|0|4|C|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@$I|Z|J|10|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|11|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|12|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|13|8|@]|9|@]|A|$]]|$1|S|3|T|5|D|7|14|8|@]|9|@]|A|$E|F]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

Shortest, most safe and easiest solution is:
<pre><code>long myValue=...;
int asInt = Long.valueOf(myValue).intValue();
</code></pre>
Do note, the behavior of <code>Long.valueOf</code> is as such:
Using this code:
<pre><code>System.out.println(&quot;Long max: &quot; + Long.MAX_VALUE);
System.out.println(&quot;Int max: &quot; + Integer.MAX_VALUE); 
long maxIntValue = Integer.MAX_VALUE;
System.out.println(&quot;Long maxIntValue to int: &quot; + Long.valueOf(maxIntValue).intValue());
long maxIntValuePlusOne = Integer.MAX_VALUE + 1;
System.out.println(&quot;Long maxIntValuePlusOne to int: &quot; + Long.valueOf(maxIntValuePlusOne).intValue());
System.out.println(&quot;Long max to int: &quot; + Long.valueOf(Long.MAX_VALUE).intValue());
</code></pre>
Results into:
<pre><code>Long max: 9223372036854775807
Int max: 2147483647
Long max to int: -1
Long maxIntValue to int: 2147483647
Long maxIntValuePlusOne to int: -2147483648
</code></pre>

blocks|key|858532|text|可以在此处进行手动类型转换：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|858533|long+x1+=+1234567891;
int+y1+=+(int)+x1;
System.out.println("in+value+is+"+%2B+y1);|code-block|syntax|javascript|858534|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|$]]

Manual typecasting can be done here:
<pre><code>long x1 = 1234567891;
int y1 = (int) x1;
System.out.println(&quot;in value is &quot; + y1);
</code></pre>

blocks|key|1073058|text|如果你想做一个安全的转换并享受Java8和Lambda表达式的使用，你可以像这样使用它：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1073059|val+->+Optional.ofNullable(val).map(Long::intValue).orElse(null)|code-block|syntax|javascript|1073060|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|$]]

If you want to make a safe conversion and enjoy the use of Java8 with Lambda expression
You can use it like:

<pre><code>val -&gt; Optional.ofNullable(val).map(Long::intValue).orElse(null)
</code></pre>

blocks|key|1073193|text|long+x;
int+y;
y+=+(int)+x|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1073194|只要数值小于2147483647且没有错误，就可以将long转换为int。|unstyled|1073195|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>long x;
int y;
y = (int) x
</code></pre>
You can cast a long to int so long as the number is less than 2147483647 without an error.

blocks|key|1073235|text|我添加了几个关键细节。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1073236|基本上，Java所做的是在32位后截断long，所以简单的类型转换就可以做到这一点：|offset|length|style|CODE|1073237|++++long+l=100000000000000000l;
++++System.out.println(Long.toString(l,2));
++++int+t=(int)l;
++++System.out.println(Integer.toString(t,2));|code-block|syntax|javascript|1073238|以下哪项输出：|1073239|101100011010001010111100001011101100010100000000000000000
++++++++++++++++++++++++++1011101100010100000000000000000|1073240|对于l=1000000043634760000l，它输出：|1073241|110111100000101101101011110111010000001110011001100101000000
+++++++++++++++++++++++++++++-101111110001100110011011000000|1073242|如果我们以适当的二进制数转换这个-101111110001100110011011000000，我们将得到从long截断的确切的32位有符号。|1073243|entityMap^0|0|J|4|0|0|0|0|2|M|0|0|G|V|1I|4|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@$D|10|E|11|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|12|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|13|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|14|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|15|8|@$D|16|E|17|F|G]]|9|@]|A|$]]|$1|S|3|T|5|J|7|18|8|@]|9|@]|A|$K|L]]|$1|U|3|V|5|6|7|19|8|@$D|1A|E|1B|F|G]|$D|1C|E|1D|F|G]]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]]|X|$]]

I'm adding few key details.
Basically what Java does is truncate <code>long</code> after 32 bits, so simple typecasting will do the trick:
<pre><code> long l=100000000000000000l;
 System.out.println(Long.toString(l,2));
 int t=(int)l;
 System.out.println(Integer.toString(t,2));
</code></pre>
Which outputs:
<pre><code>101100011010001010111100001011101100010100000000000000000
 1011101100010100000000000000000
</code></pre>
for <code>l=1000000043634760000l</code> it outputs:
<pre><code>110111100000101101101011110111010000001110011001100101000000
 -101111110001100110011011000000
</code></pre>
If we convert this <code>-101111110001100110011011000000</code> in proper two's compliment we will get the exact 32-bit signed truncated from the <code>long</code>.

blocks|key|858604|text|我也面临着这个问题。为了解决这个问题，我首先将long转换为String，然后将其转换为int。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|858605|int+i+=+Integer.parseInt(String.valueOf(long));|code-block|syntax|javascript|858606|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 Also Faced This Problem.
To Solve This I have first converted my long to String then to int.
<pre><code>int i = Integer.parseInt(String.valueOf(long));
</code></pre>

blocks|key|1073014|text|long+x=+3120L；//取任意长值int+z=+x.intValue()；//也可以用同样的方法将double转换为int|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1073015|如果你需要直接隐蔽|1073016|longvalue.intvalue()；|1073017|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|$]]

long x = 3120L; //take any long value
int z = x.intValue(); //you can convert double to int also in the same way

if you needto covert directly then

longvalue.intvalue();

blocks|key|1072941|text|Long+l+=+100;
int+i+=+Math.round(l);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1072942|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>Long l = 100;
int i = Math.round(l);
</code></pre>

blocks|key|858401|text|在Spring中，有一种严格的方法可以将long类型转换为int类型|type|unstyled|depth|inlineStyleRanges|entityRanges|data|858402|不仅lnog可以转换为int，任何类型的类扩展Number都可以转换为其他Number类型，这里我将向您展示如何将long类型转换为int类型，其他类型反之亦然。|858403|Long+l+=+1234567L;
int+i+=+org.springframework.util.NumberUtils.convertNumberToTargetClass(l,+Integer.class);|code-block|syntax|javascript|858404|​|858405|📷|atomic|offset|length|858406|858407|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/7d23ac8856bd0c1dacf6a425e9b87c38.jpeg|imageAlt^0|0|0|0|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|10|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|11|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|12|8|@]|9|@]|A|$]]|$1|K|3|L|5|M|7|13|8|@]|9|@$N|14|O|15|1|16]]|A|$]]|$1|P|3|J|5|6|7|17|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X|Y|-4]]]]

In Spring, there is a rigorous way to convert a long to int

not only lnog can convert into int,any type of class extends Number can convert to other Number type in general,here I will show you how to convert a long to int,other type vice versa.

<pre><code>Long l = 1234567L;
int i = org.springframework.util.NumberUtils.convertNumberToTargetClass(l, Integer.class);
</code></pre>

<img src="https://i.stack.imgur.com/BElEq.jpg" alt="convert long to int">

How can I convert a long to int in Java?

How can I convert a long to int in Java?

如何在Java中将long类型转换为int类型？

问如何在Java中将long类型转换为int类型？
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