What is the principle of JavaHashMap and example parsing?
Today, I would like to talk to you about the principle of JavaHashMap and example analysis, many people may not know much about it. In order to make you understand better, the editor summarized the following content for you. I hope you can get something according to this article.
Example 1: key-value pair of HashMap
The way HashMap stores data is key-value pairs.
Package collection; import java.util.HashMap
Public class TestCollection {
Public static void main (String [] args) {
HashMap dictionary = new HashMap ()
Dictionary.put ("adc", "physical Hero")
Dictionary.put ("apc", "Magic Hero")
Dictionary.put (t, Tank)
System.out.println (dictionary.get ("t"))
}
}
Example 2: keys cannot be repeated and values can be repeated
For HashMap, key is unique and cannot be repeated.
Therefore, inserting different value into the Map with the same key causes the old element to be overwritten, leaving only the last inserted element.
However, the same object can be inserted into the map as a value, as long as the corresponding key is different
Package collection; import java.util.HashMap; import charactor.Hero
Public class TestCollection {
Public static void main (String [] args) {
HashMap heroMap = new HashMap ()
HeroMap.put ("gareen", new Hero ("gareen1"))
System.out.println (heroMap)
/ / key already has value for gareen. Putting data in gareen as key will cause the original hero to be overwritten.
/ / No new elements will be added to Map heroMap.put ("gareen", new Hero ("gareen2"))
System.out.println (heroMap)
/ / clear map heroMap.clear ()
Hero gareen = new Hero ("gareen")
/ / the same object can be inserted into the map as a value, as long as the corresponding key is different.
HeroMap.put ("hero1", gareen)
HeroMap.put ("hero2", gareen)
System.out.println (heroMap)
}
}
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