HashMap可以包含键/值的自定义类吗? [英] Can HashMap contain custom class for key/value?
问题描述
在HashMap< K , V >中,可以将 K 或 V 用作自定义类对象,而不是包装器类对象?
In HashMap<K,V>, can K or V be custom class object instead of wrapper class objects??
import java.util.HashMap;
import java.util.Map;
public class Test {
public static void main(String[] args) {
Test test=new Test();
HashMap<String, test> a= new HashMap<String, test>();
}
}
发生错误:测试无法解析为一种类型.
Error occurs: test cannot be resolved to a type.
先谢谢了.问候.
推荐答案
在hashmap中,可以将自定义类型作为键/值对包含.
In hashmap, yes you can include custom types as Key/Value pair.
但这不应该是 object
,它必须明确地是 type
.
but that should not be object
, it must of clearly a type
.
表示一个 class
,您可以提及它成为自定义类型的 type
.
means a class
you can mention which becomes type
for custom types.
示例
您可以将String类型变量定义为 String s ="abc";
you can define String type variable as String s = "abc";
现在如果我们尝试像下面这样写
now if we try to write like below
HashMap<String, s> a= new HashMap<String, s>();
它不会编译为's
的类型,而不是 String
类型的对象,
it wont compile as 's'
is not the type rather than its an object of type String
,
因此它应该变成下面的样子
hence it should become like below
HashMap<String, String> a= new HashMap<String, String>();
所以您的代码如下
Test test=new Test();
HashMap<String, test> a= new HashMap<String, test>();
应该成为
Test test=new Test();
HashMap<String, Test> a= new HashMap<String, Test>();
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