Question

我基本上是一个php程序员，现在只是想知道（或游荡！）在java海岸边。当然还有救生船，堆栈溢流。

我正努力在java中创建一个多维数组，就像在php中一样，它很简单$array["bla"]["blabla"]["blablabla"]...

这就是我想要实现的目标

Array
(
    [user] => UserName
    [groups] => Array
        (
            [0] => group1
            [1] => group2
            [2] => group3
        )

    [categories] => Array
        (
            [0] => category1
            [1] => category2
            [2] => category3
        )

    [notification] => user notification string
    [departments] => Array
        (
            [0] => department1
            [1] => department2
            [2] => department3
            [3] => department4
        )

    [sub-deptmnt] => Array
        (
            [department1] => Array
                (
                    [0] => subdep1
                    [1] => subdep2
                )

            [department2] => Array
                (
                    [0] => another-subdep1
                    [1] => another-subdep2
                    [2] => another-subdep3
                )

        )

)

php中的

是

$array["user"] = "UserName";
$array["groups"] = array("group1","group2","group3");
$array["categories"] =array("category1","category2","category3");
$array["notification"] = "user notification string";
$array["departments"] = array("department1","department2","department3","department4");
$array["sub-deptmnt"] = array("department1" => array("subdep1","subdep2"),"department2"=> array("another-subdep1","another-subdep2", "another-subdep3"));

有人请帮我继续......

编辑：使用php示例澄清所需的数组

Answer 1

Java中这样的代码的良好实践不是为此使用无类型数组，而是为了生成实际类型的对象：

class Whatever {
  private final String username;
  private final List<Group> groups;
  ...
}
class Group {
  ...
}

Answer 2

像这样定义你的对象

    class SampleModel{

        String userName;
        List<String> groups  ;
        List<String> categories;
        String notification;
        List<String> departments;
        Map<String,List<String>> sub_deptmnt;

        //getter and setter 
    }

Answer 3

如果你事先知道密钥是什么，那么最好用Prabhakaran向你展示的方式设置一个带有字段和getter / setter方法的类。

如果键可以是动态的，那么：相当于PHP的关联数组是Map<String,Object>。

Map<String,Object> arr = new HashMap<String,Object> ();

然后创建一个数组元素：

arr.put ("user", userName);

并检索它：

String userName = (String)(arr.get ("user"));

您可以将数组元素设置为数组，或ArrayList s或其他Map<String,Object>映射，从而获得多维数组。但问题是Java是强类型的，这意味着get方法将返回一个Object，你必须将它强制转换为你期望的类型：

String[] categories = (String[])(arr.get ("categories"));

或

ArrayList<String> categories = (ArrayList<String>)(arr.get ("categories"));

如果先前为“categories”存储的对象的类型错误，则会抛出异常。

如果不出意外，您至少应该查看collections tutorial，因为如果您将使用Java，您肯定需要知道这些内容。

[注意：我还没有测试过任何上述代码。我想我做对了。]

Java中的多维数组。那复杂吗？

3 个答案: