3.2 pairs (pair) and stripes (stripe)
A common practice of synchronization in mapreduce programs is to adapt data to the execution framework by building complex keys and values. We have covered this technology in the previous chapter, that is,
Sass function -- map, sass -- map
MapThe map of Sass is often called a Data map, or an array.Key: valueIn pairs.
1 $map: (2 $key1: value1,3 $key2: value2,4 $key3: value35 )
First, there is a variable similar to Sass, with$Add namespace
Learn the basics of one of the most common collection types and how to optimize your map for data specific to your application.
Related downloads:· Jack's HashMap test.· Oracle JDeveloperG
The collection class in Java.util
Learn the basics of one of the most common collection types and how to optimize your map for data specific to your application.
Related downloads:· Jack's HashMap test.· Oracle JDeveloperG
The collection class in Java.util
Map is used to save data with ing relationships (key-vlaue ). Duplicate Map keys are not allowed. That is, if two keys of the same Map object are compared using the equals method, false is always returned.
Map contains a keySet () method, which is
Java: // usage of Comparator and Comparable (output the key-value pairs of the map set in sequence as required ),
Import java. util .*;
Public class Person implements Comparable // compare the attributes of Person.
{
Private String name;
Private
Java Collection Framework summary (5) use of The--map interfaceMap is used to hold data that has a mapping relationship (key-vlaue). The key of map does not allow repetition, that is, any two key of the same map object is always returned false by
javascript does not have a map, but has a map function-_-! do it yourself, clothed (function () {try{function directory () {this.key = new array (); This.value = new array ();} Add Directory.prototype.add = function (key,value) {//key whether to
Document directory
IV. For details about map tasks, see
V. Reduce task details
Vi. Distributed support
VII. Summary
2. Distributed Computing (MAP/reduce)
Distributed Computing is also a broad concept. In this case, it refers
The distributed
Map stores data in the form of key/numeric pairs, and arrays are similar to indexes that exist in arrays, which are themselves objects.The interface of Mapmap---Implementation MapThe inner class of Map.entry--map, which describes the key/value pairs
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