Safe navigation with Object to Decimal in Map<String,Object>

Question

Today I was shown a code I though could use some Safe navigation improvement, after some tries I don't understand how to apply safe navigation in this scenario with an Object that has to be converted to Decimal.

Map<String,Object> testMap =new Map<String,Object> {'field1'=>null,'field2'=>3.3};

// This has to be refactored using safe navigation
Decimal new_decimal = testMap.get('field1') != null?  ((Decimal)testMap.get('field1').set_scale(2)):null

I tried something like

Decimal new_decimal = (Decimal)testMap.get('field1')?.set_scale(2);

But I get

Method does not exist or incorrect signature: void set_scale(Integer) from the type Object

How can I get my expected result using Safe navigation?

Answer 1

The way to use it is the following one

Decimal new_decimal = ((Decimal) testMap.get('field1'))?.setScale(2);

which has been suggested already. The problem is the method that you were using as set_scale() is not a method, it is setScale().