DoubleIntListHashMap (SystemDS 2.0.0 API)

```
public class DoubleIntListHashMap
extends CustomHashMap
```
This class provides a memory-efficient replacement for HashMap<Double,IntArrayList> for restricted use cases. TODO: Fix allocation of size such that it contains some amount of overhead from the start, to enable hashmap performance.

Nested Classes
Modifier and Type	Class and Description
`class`	`DoubleIntListHashMap.DIListEntry`

Constructors
Constructor and Description
`DoubleIntListHashMap()`
`DoubleIntListHashMap(int init_capacity)`

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`appendValue(double key, IntArrayList value)`
`ArrayList<DoubleIntListHashMap.DIListEntry>`	`extractValues()`
`IntArrayList`	`get(double key)`

Methods inherited from class org.apache.sysds.runtime.compress.utils.CustomHashMap
size

public DoubleIntListHashMap(int init_capacity)

public void appendValue(double key,
                        IntArrayList value)

public ArrayList<DoubleIntListHashMap.DIListEntry> extractValues()

Class DoubleIntListHashMap