(JAVA/KOTLIN) 我可以“转换”字符串以调用现有变量吗？ 像“varname”.getvariable？

Question

Can I use a string to call an existing variable or object by name? The question is kind of abstract but I'm looking for something like this.

Example

var number = 5

var getnumber = "number"

if (getnumber.(???) > 10)
{...}

or 

if ("number".(???) > 10)

{...}```

Answer 1

This is impossible: At the class level, local variable names do not exist at all.

The usual solution is to stop thinking 'python' or 'javascript', where each object is a kind of HashMap<String, Object> , and think java.

If you just can't get your head out of python/javascript space, or the problem fundamentally boils down to this idea, well, you have your answer:

Make a Map<String, Object> instead of a local variable:

Map<String, Integer> map = new HashMap<>();
map.put("number", 5);
var getNumber = "number";
if (map.get(getNumber) > 10) { .... }

Answer 2

In case you have a fixed amount of entries, you might use an enum:

private enum class Size(val cm: Int) {
    SMALL(50),
    MEDIUM(100),
    LARGE(150),
}

Usage could be like:

val sizeOne = Size.MEDIUM
val sizeTwo = Size.LARGE

if(sizeOne.cm > sizeTwo.cm ) { ... }

val sizeHundred = Size.values().find { it.cm == 100 }