Gets the number of text characters appear

Gets the number of text characters appear

• Gets the number of times each character appears on a text, and the result is written on times.txt
  • analysis:
  • 1. Create an object input stream Buffered
  • 2. Create a two-column collection object TreeMap
  • 3. The double row set, when stored in storage do determined character read, if not contain this key, and a key storage will, if it contains the key, the keys and values ​​added to the storage
  • 4. Close the input stream
  • 5. Create output stream object
  • 6. traverse the collection of the contents of the collection written in times.txt
  • 7. Close the output stream

package com.heima.test;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.TreeMap;

public class Test02 {

	public static void main(String[] args) throws IOException {
		//1.创建带缓冲的输入流对象
		BufferedReader br = new BufferedReader(new FileReader("zzz.txt"));
		//2.创建双列集合对象TreeMap
		TreeMap<Character, Integer> tm = new TreeMap<>();
		//3.将读到的字符存储在双列集合中,存储的时候要做判断,如果不包含这个键,就将键和1存储,如果包含这个键,就将该键和值加1存储
		int ch;
		while((ch = br.read()) != -1) {
			char c = (char)ch;					//强制类型转换
			/*if(!tm.containsKey(c)) {
				tm.put(c, 1);
			}else {
				tm.put(c, tm.get(c) + 1);
			}*/
			tm.put(c, !tm.containsKey(c) ? 1 : tm.get(c) + 1);
		}
		//4.关闭输入流
		br.close();
		//5.创建输出流对象
		BufferedWriter bw = new BufferedWriter(new FileWriter("times.txt"));
		//6.遍历集合将集合中的内容写到times.txt中
		for(Character key : tm.keySet()) {
			switch (key) {
			case '\t':
				bw.write("\\t" + "=" + tm.get(key)); 	
				break;
			case '\n':
				bw.write("\\n" + "=" + tm.get(key)); 
				break;
			case '\r':
				bw.write("\\r" + "=" + tm.get(key)); 
				break;
			default:
				bw.write(key + "=" + tm.get(key)); 			//写出键和值
				break;
			}
			bw.newLine();
		}
		//7.关闭输出流
		bw.close();
	}
}