Java Map Interface

Streams

  What is the flat map? how it is different from map?

• Map is used for data transformation whereas flat map is used for data transformation and flattering, the data.
• Map takes stream as input and output as another stream.
• It’s mapper function produces single value for each input value. Hence it is called as one to one mapping.
• It processes, a stream of values.
• It does Only mapping.
• Its mapper function produces a single value for each input value.
• It is a one-to-one mapping
• Data transformation from stream to stream.
• Use this method when the function is producing a single value for each input value.
• Flatmap is when map is added with flattening.
• It produces stream of values
• It performs mapping as well as flattening.
• Its map a function produces multiple values for each input value.
• It is one too many mapping.
• Data is transferred from one stream of stream to single stream.
• Use this method when the mapper function is producing multiple values for each input value.
• Flat map also takes a stream of input value and gives an output stream.
• Its map function produces multiple value for each input value. Hence it is called as one to many mapping.
• It is used to convert us stream of stream data to single stream, for example, a list of list of strings to a single list of strings.