What is a reasonable implementation of this uml graph in java?

where Enumeration,Eiche,Buche,Esche is german and means enum, oak, beech, ash. My attempt was the following

public class Material{

public static enum material{
oak, beech, ash
}

public int[] materialCost ={1,2,3};
}

The problem ist that somewhere in my homework-excercise I find Table(Material.oak) so I know my attempt must be wrong. Can anyone help?