向哈希表Java添加值

Question

Sorry, new to Java, probably a really simple question.

Let's say I have an outter map, that has a (key, inner map), and in the inner map I have (String, Double).

So it looks something like this.

    HashMap<String, Double> inner = new HashMap<String, Double>();
    HashMap<Integer, Map<String, Double>> outter = new HashMap<Integer, Map<String, Double>>();
    inner.put("MyVal", 24.5930553450692151964475150);
    inner.put("MyVal2", 48.6514790522118734018261775);
    outter.put(20151205, inner)

I end up with and outter map like this:

{20151205={MyVal=24.593055345069214, MyVal2=48.651479052211876}}

Now let's say I no longer have access to the inner map, so I can't put any more values in it. But, I want to add a MyVal3 using only the outter map.

How can this be done?

I want to end up with something like this using code for only the outter map.

{20151205={MyVal=24.593055345069214, MyVal2=48.651479052211876, MyVal3=48.4846855555555}}

Thanks a lot! Couldn't find exactly this question elsewhere on SO.

As always thanks everyone!

Answer 1

You always have access to the inner map, but you need to get the key.

Then you simply put.

outter.get(20151205).put("MyVal3", 48.4846855555) ;

Beware of the Nullpointerexception when you try to get a key that doesn't exist