如何在Java中创建一些变量类型别名-HowdoIcreatesomevariabletypealiasinJava

38  

There are no aliases in Java. You can extend the HashMap class with your class like this:

Java中没有别名。您可以像这样使用类扩展HashMap类:

public class TheNewType extends HashMap {
    // default constructor
    public TheNewType() {
        super();
    }
    // you need to implement the other constructors if you need
}

But keep in mind that this will be a class it won't be the same as you type HashMap

但请记住,这将是一个类,它与键入HashMap 不同

9  

There is no typedef equivalent in Java, and there is no common idiom for aliasing types. I suppose you could do something like

Java中没有typedef等价物,并且对于别名类型没有常见的习惯用法。我想你可以做点什么

class StringMap extends HashMap {}

but this is not common and would not be obvious to a program maintainer.

但这并不常见,对于程序维护者来说并不明显。

7  

Although Java doesn't support this, you can use a generics trick to simulate it.

虽然Java不支持这一点,但您可以使用泛型技巧来模拟它。

class Test {
     void x(I i, L l) {
        System.out.println(
            i.intValue() + ", " + 
            l.longValue()
        );
    }
}