blocks|key|1064011|text|int+theArray[]+=+new+int[20];
System.out.println(theArray.length);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1064012|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>int theArray[] = new int[20];
System.out.println(theArray.length);
</code></pre>

blocks|key|1064041|text|这方面没有内置的功能。此计数是其特定于整个用户的计数。维护一个计数器或者别的什么。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1064042|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|$]]

There is no built-in functionality for this. This count is in its whole user-specific. Maintain a counter or whatever.

blocks|key|849753|text|在定义数组时，您需要留出一块内存来存放数组中要包含的所有项。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|849754|这将有一个默认值，这取决于数组成员类型的类型。|849755|你不能做的是找出你已经填充的项目的数量，除了在你自己的代码中跟踪它。|849756|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|$]]

When defining an array, you are setting aside a block of memory to hold all the items you want to have in the array.

This will have a default value, depending on the type of the array member types.

What you can't do is find out the number of items that you have populated, except for tracking it in your own code.

blocks|key|1064094|text|我认为您可能需要的是一个ArrayList而不是一个数组。这将允许您执行以下操作：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1064095|ArrayList<Integer>+arr+=+new+ArrayList<Integer>(20);
System.out.println(arr.size());|code-block|syntax|javascript|1064096|输出将是0。|1064097|然后，您可以向列表中添加内容，它将为您跟踪计数。(它还会根据需要增加后备存储的大小。)|1064098|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/6/docs/api/java/util/ArrayList.html^0|C|9|C|9|0|0|0|4|1|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|16|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

What I think you may want is an <a href="http://download.oracle.com/javase/6/docs/api/java/util/ArrayList.html" rel="noreferrer"><code>ArrayList&lt;Integer&gt;</code></a> instead of an array. This will allow you do to:

<pre><code>ArrayList&lt;Integer&gt; arr = new ArrayList&lt;Integer&gt;(20);
System.out.println(arr.size());
</code></pre>

The output will be <code>0</code>.

Then, you can add things to the list, and it will keep track of the count for you. (It will also grow the size of the backing storage as you need as well.)

blocks|key|849847|text|遍历它并计算非空的元素：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|849848|int+counter+=+0;
for+(int+i+=+0;+i+<+theArray.length;+i+%2B%2B)
++++if+(theArray[i]+!=+null)
++++++++counter+%2B%2B;|code-block|syntax|javascript|849849|这可以通过使用for:each循环和诸如此类的命令来整理，但这是摘要。|849850|或者保留一个计数器，当你添加一个元素时，递增它。|849851|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]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Iterate through it and count the elements which aren't null:

<pre><code>int counter = 0;
for (int i = 0; i &lt; theArray.length; i ++)
 if (theArray[i] != null)
 counter ++;
</code></pre>

This can be neatened up by using for:each loops and suchlike, but this is the jist.

Either that, or keep a counter and whenever you add an element, increment it.

blocks|key|849933|text|Java没有数组中所用元素的“计数”的概念。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|849934|为了实现这一点，Java使用了ArrayList。List是在一个数组之上实现的，当它确定它不够大时(有时当它太大时)，该数组就会调整大小。|offset|length|style|CODE|849935|要获得计数，可以使用mylist.size()来确保使用mylist.ensureCapacity(20)的容量(底层数组支持)。为了消除额外的容量，您可以使用mylist.trimToSize()。|849936|entityMap^0|0|F|9|P|4|0|A|D|S|P|28|J|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@$D|N|E|O|F|G]|$D|P|E|Q|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|R|8|@$D|S|E|T|F|G]|$D|U|E|V|F|G]|$D|W|E|X|F|G]]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|K|$]]

Java doesn't have the concept of a "count" of the used elements in an array.

To get this, Java uses an <code>ArrayList</code>. The <code>List</code> is implemented on top of an array which gets resized whenever the JVM decides it's not big enough (or sometimes when it is too big). 

To get the count, you use <code>mylist.size()</code> to ensure a capacity (the underlying array backing) you use <code>mylist.ensureCapacity(20)</code>. To get rid of the extra capacity, you use <code>mylist.trimToSize()</code>.

blocks|key|1064314|text|您可以使用for+each循环并计算有意义的整数值的数量。您也可以使用ArrayList，它将为您跟踪国家。每次在列表中添加或删除对象时，它都会自动更新计数。调用size()方法将给出当前元素的数量。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1064315|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|$]]

You can use a for each loop and count the number of integer values that are significant. You could also use an ArrayList which will keep track of the couny for you. Everytime you add or remove objects from the list it will automatically update the count. Calling the size() method will give you the current number of elements.

blocks|key|850009|text|如果您假设0不是数组中的有效项，则以下代码应该可以工作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|850010|+++public+static+void+main(+String[]+args+)
+++{
++++++int[]+theArray+=+new+int[20];
++++++theArray[0]+=+1;
++++++theArray[1]+=+2;

++++++System.out.println(count(theArray));
+++}

+++private+static+int+count(int[]+array)+
+++{
++++++int+count+=+0;
++++++for(int+i+:+array)
++++++{
+++++++++if(i+>+0)
+++++++++{
++++++++++++count%2B%2B;
+++++++++}
++++++}
++++++return+count;
+++}|code-block|syntax|javascript|850011|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 assume that 0 is not a valid item in the array then the following code should work:

<pre><code> public static void main( String[] args )
 {
 int[] theArray = new int[20];
 theArray[0] = 1;
 theArray[1] = 2;

 System.out.println(count(theArray));
 }

 private static int count(int[] array) 
 {
 int count = 0;
 for(int i : array)
 {
 if(i &gt; 0)
 {
 count++;
 }
 }
 return count;
 }
</code></pre>

blocks|key|1064416|text|不就是：System.out.println(Array.length);吗？因为这似乎就是你要找的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1064417|entityMap^0|4|X|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|$]]

Isn't it just: <code>System.out.println(Array.length);</code>? Because this is what it seems like you are looking for.

blocks|key|1064453|text|您可以声明一个与数组长度相同的布尔值数组：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1064454|true:使用|1064455|false:未使用|1064456|并将相同单元格编号的值更改为true。然后，您可以使用for循环计算使用了多少个单元格。|1064457|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

You can declare an array of booleans with the same length of your array:

true: is used 
false: is not used

and change the value of the same cell number to true. Then you can count how many cells are used by using a for loop.

blocks|key|850124|text|您也可以将其设置为Integer数组。这样一来，每一项都将为空。然后只计算非空值的数量。这仍然允许您像以前一样添加int，因为Java会对原语及其包装器进行自动装箱和拆箱。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|850125|Integer[]+numbers+=+new+Integer[30];

int+count+=+0;
for+(Integer+num+:+numbers)
++++if+(num+!=+null)+count%2B%2B;

System.out.println(count);|code-block|syntax|javascript|850126|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 could also make it an Integer array. That way each item will be null. Then just count the number of non-null values. This still allows you to add ints, like you could before since Java does autoboxing and unboxing of primitives and their wrappers.
<pre class="lang-java prettyprint-override"><code>Integer[] numbers = new Integer[30];

int count = 0;
for (Integer num : numbers)
 if (num != null) count++;

System.out.println(count);
</code></pre>

Say i have the array

<pre><code>int theArray = new int[20];
</code></pre>

The length of the array is 20 but the count is 0. How can i get the count?

How do you count the elements of an array in java

Java

假设我有一个数组int theArray = new int[20];数组的长度是20，但计数是0。我怎么才能拿到点数？

问在java中如何计算数组的元素？
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