1. Guide package
import java.io.BufferedReader; import java.io.FileReader; import java.util.HashMap; import java.util.Map; import java.util.Set;
2. Code
public static void main(String[] args) throws Exception { //Create a map collection to store the character and the number of times the character appears Map<Character,Integer> map = new HashMap<Character,Integer>(); //Create a character input buffer stream object, associated with the word.txt file BufferedReader br = new BufferedReader(new FileReader("word.txt")); //Create c to receive the characters read each time, the bottom layer will convert the read characters to int type by default int c; // read one character at a time while((c=br.read())!=-1) { // Convert to char type char ch = (char) c; //Get value according to key Integer value = map.get(ch); //If the value is empty, the character has not been stored if(value == null) { //Storage, the first storage, the value is 1 map.put(ch, 1); }else { //Indicates that the value has been stored for times, as long as it is +1 on the basis of the value map.put(ch, value+1); } } // When the statistics are completed, print them out Set<Character> keys = map.keySet(); for (Character key : keys) { Integer value = map.get(key); System.out.println(key+":"+value); } }