Java中的Arduino Map等效函数

Question

Is there a function similar to the Map function in Arduino for Java?

I need to map a range of values to another range of values, so I was wondering if there was something similar to it in Java, I've been searching but I only get the Java's Map function.

Answer 1

The code of map() from Arduino's library is this:

long map(long x, long in_min, long in_max, long out_min, long out_max)
{
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

This will work in Java just the same - no real magic. But standard Java has nothing predefined like this.

Answer 2

Uh, Java doesn't have a 'Map' function, it has a Map type in the Collections (java.util), with multiple implementations. But this is just a storage mechanism, basically resulting in key=>value pairs. Based on my reading of the Arduino docs you linked, you'd need to implement your own method to map the value appropriately.

Answer 3

You could do something like this:

Map<K,V> mapValues(Collection<K> keys, Collection<V> values) {
    if(keys.size() != values.size()) throw new ... // pick your poison there
    Map<K,V> map = new HashMap<K,V>();
    Iterator<K> keyIter = keys.iterator();
    Iterator<V> valIter = values.iterator();
    while(keyIter.hasNext()) {
        K key = keyIter.next();
        V val = valIter.next();
        map.put(key,val);
    }
    return map;
}