blocks|key|1006215|text|数组没有indexOf()方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1006216|也许这个Apache+Commons+Lang+ArrayUtils方法就是您要找的。|1006217|import+org.apache.commons.lang3.ArrayUtils;

String[]+colours+=+{+"Red",+"Orange",+"Yellow",+"Green"+};

int+indexOfYellow+=+ArrayUtils.indexOf(colours,+"Yellow");|code-block|syntax|javascript|1006218|entityMap|0|LINK|mutability|MUTABLE|url|http://commons.apache.org/proper/commons-lang/javadocs/api-release/org/apache/commons/lang3/ArrayUtils.html^0|4|9|0|O|A|O|A|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@$9|10|A|11|1|12]]|E|$]]|$1|H|3|I|5|J|7|13|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

Array has no <code>indexOf()</code> method.

Maybe this Apache Commons Lang <a href="http://commons.apache.org/proper/commons-lang/javadocs/api-release/org/apache/commons/lang3/ArrayUtils.html" rel="noreferrer"><code>ArrayUtils</code></a> method is what you are looking for

<pre><code>import org.apache.commons.lang3.ArrayUtils;

String[] colours = { "Red", "Orange", "Yellow", "Green" };

int indexOfYellow = ArrayUtils.indexOf(colours, "Yellow");
</code></pre>

blocks|key|792338|text|对于原语，如果你想避免装箱，Guava为原语数组提供了帮助器，例如Ints.indexOf(int[]数组，int+target)|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|792339|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/p/guava-libraries/|1|http://guava-libraries.googlecode.com/svn/tags/release09/javadoc/com/google/common/primitives/Ints.html#indexOf%2528int%255B%255D,%2520int%2529^0|E|5|0|X|C|1|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]|$A|R|B|S|1|T]]|C|$]]|$1|D|3|-4|5|6|7|U|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]|L|$5|G|H|I|C|$J|M]]]]

For primitives, if you want to avoid boxing, <a href="http://code.google.com/p/guava-libraries/">Guava</a> has helpers for primitive arrays e.g. <a href="http://guava-libraries.googlecode.com/svn/tags/release09/javadoc/com/google/common/primitives/Ints.html#indexOf%28int%5B%5D,%20int%29">Ints.indexOf</a>(int[] array, int target)

blocks|key|792102|text|Java+ArrayList有一个indexOf方法。Java数组没有这样的方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|792103|entityMap^0|5|9|H|7|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|$]]

Java <code>ArrayList</code> has an <code>indexOf</code> method. Java arrays have no such method.

blocks|key|792185|text|除了自己编码之外，我不记得数组上有什么"indexOf“...但是，如果数组包含原始类型，则可以使用众多java.util.Arrays#binarySearch(...)方法(请参阅Arrays+javadoc)中的一个|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|792186|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/1.5.0/docs/api/java/util/Arrays.html^0|1G|Y|2K|E|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

I don't recall of a "indexOf" on arrays other than coding it for yourself... though you could probably use one of the many <code>java.util.Arrays#binarySearch(...)</code> methods (see the <a href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Arrays.html" rel="noreferrer">Arrays javadoc</a>) if your array contains primitive types

blocks|key|1006152|text|List接口有一个indexOf()方法，您可以使用数组的asList()方法从数组中获取列表。除此之外，Array本身没有这样的方法。它确实有一个用于排序数组的binarySearch()方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1006153|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|$]]

The List interface has an indexOf() method, and you can obtain a List from your array with Array's asList() method. Other than that, Array itself has no such method. It does have a binarySearch() method for sorted arrays.

blocks|key|1006082|text|数组本身没有这种方法。然而，列表可以做到这一点：indexOf|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1006083|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/1.5.0/docs/api/java/util/ArrayList.html#indexOf%2528java.lang.Object%2529^0|O|7|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Arrays themselves do not have that method. A List, however, does:
<a href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/ArrayList.html#indexOf%28java.lang.Object%29" rel="nofollow">indexOf</a>

blocks|key|1006070|text|您可能在考虑java.util.ArrayList，而不是数组。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1006071|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/1.4.2/docs/api/java/util/ArrayList.html^0|6|J|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

You're probably thinking of the <a href="http://download.oracle.com/javase/1.4.2/docs/api/java/util/ArrayList.html" rel="nofollow">java.util.ArrayList</a>, not the array.

blocks|key|792393|text|java数组中没有直接的indexOf函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|792394|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 direct indexOf function in java arrays.

blocks|key|792469|text|Jeffrey+Hantin的答案是好的，但它有一些限制，如果它这样做或否则到那个……|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|792470|你可以编写自己的扩展方法，它总是以你想要的方式工作。|792471|Lists.indexOf(array,+x+->+item+==+x);+//+compare+in+the+way+you+want|code-block|syntax|javascript|792472|这是您的分机|792473|public+final+class+Lists+{
++++private+Lists()+{
++++}

++++public+static+<T>+int+indexOf(T[]+array,+Predicate<T>+predicate)+{
++++++++for+(int+i+=+0;+i+<+array.length;+i%2B%2B)+{
++++++++++++if+(predicate.test(array[i]))+return+i;
++++++++}
++++++++return+-1;
++++}

++++public+static+<T>+int+indexOf(List<T>+list,+Predicate<T>+predicate)+{
++++++++for+(int+i+=+0;+i+<+list.size();+i%2B%2B)+{
++++++++++++if+(predicate.test(list.get(i)))+return+i;
++++++++}
++++++++return+-1;
++++}

++++public+interface+Predicate<T>+{
++++++++boolean+test(T+t);
++++}
}|792474|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/4962413/4767498^0|0|E|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|6|7|10|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|11|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|9|@]|C|$]]|$1|M|3|N|5|H|7|13|8|@]|9|@]|C|$I|J]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]]]

<a href="https://stackoverflow.com/a/4962413/4767498">Jeffrey Hantin</a>'s answer is good but it has some constraints, if its this do this or else to that...

You can write your own extension method and it always works the way you want.

<pre><code>Lists.indexOf(array, x -&gt; item == x); // compare in the way you want
</code></pre>

And here is your extension

<pre><code>public final class Lists {
 private Lists() {
 }

 public static &lt;T&gt; int indexOf(T[] array, Predicate&lt;T&gt; predicate) {
 for (int i = 0; i &lt; array.length; i++) {
 if (predicate.test(array[i])) return i;
 }
 return -1;
 }

 public static &lt;T&gt; int indexOf(List&lt;T&gt; list, Predicate&lt;T&gt; predicate) {
 for (int i = 0; i &lt; list.size(); i++) {
 if (predicate.test(list.get(i))) return i;
 }
 return -1;
 }

 public interface Predicate&lt;T&gt; {
 boolean test(T t);
 }
}
</code></pre>

blocks|key|1006368|text|int+findIndex(int+myElement,+int[]+someArray){
+int+index+=+0;
+for(int+n:+someArray){
+++if(myElement+==+n)+return+index;
+++else+index%2B%2B;
+}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1006369|注意:您可以将此方法用于int类型的数组，也可以将此算法用于稍作更改的其他类型|unstyled|1006370|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>int findIndex(int myElement, int[] someArray){
 int index = 0;
 for(int n: someArray){
 if(myElement == n) return index;
 else index++;
 }
}
</code></pre>

Note: you can use this method for arrays of type int, you can also use this algorithm for other types with minor changes

I must be missing something very obvious, but I've searched all over and can't find this method.

Where is Java's Array indexOf?

Java

我肯定遗漏了一些非常明显的东西，但是我到处都找不到这个方法。

问Java的数组indexOf在哪里？
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回答 10

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