How do you use char in Java?

You can use a java Map and map a char to an int. You can then iterate over the characters in the string and check if they have been added to the map, if they have, you can then increment its value. For example: At the end you will have a count of all the characters you encountered and you can extract their frequencies from that.
For More Information Please Refer:
https://stackoverflow.com/questions/6712587/how-to-count-frequency-of-characters-in-a-string
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