By your description, it sounds to me that what you really want is that the value of your map contains 2 values. In fact, the fact that you use a Map for this seems an abuse of its function and it is also true that there will be a certain degree of waste.
The correct way to do this is to define a class for that purpose instead of using another map.
Example (adjust the names according to your need):
public class MiTuple {
private String miString;
private Double miDouble;
public MiTuple(String miString, Double miDouble) {
this.miString = miString;
this.miDouble = miDouble;
}
public String getMiString() {
return this.miString;
}
public Double getMiDouble() {
return this.miDouble;
}
}
In this way, you can define your map in a more usual way without "waste", but with all the data you need:
Map<Integer, MiTuple>
... or, as you comment @ Awes0meM4n, and as you can find in this answer , you can create a class equivalent using generic to represent 2 values of any type. This would allow you to recover the same class for different situations:
public class Tuple<X, Y> {
public final X x;
public final Y y;
public Tuple(X x, Y y) {
this.x = x;
this.y = y;
}
}
In this case, you would define your map in the following way:
Map<Integer, Tuple<String, Double>>