Use of bufferedwriter and BufferedReader

Hello everyone , I meet you again , I'm your friend, Quan Jun .

• BufferedWriter

BufferedWriter Starting heel FileWriter There is no difference in the use of , It belongs to character output stream .

BufferedWriter More efficient , Because it has a built-in length of 8192 Array of characters , That is to say 8K Array of characters . It looks like , If we write something in the document , If the contents do not fill the array , Will automatically wait until we fill up , Then write to the hard disk together . The running speed of hard disk is very slow . But we can also use close() Method , Although it may not be full , But you can still force it to write to the hard disk .

Like a black car driver , He solicits customers , Usually you don't pull a guest away , Usually the whole car is full of people , To drive , But sometimes I can't find anyone , I have to go . It will still start .

besides ,BufferedWriter It also provides a way to wrap lines automatically —— newLine() Method , It will vary according to the operating system , Automatically add line breaks . In actual development , If you want a new line , Try to use newLine() Method .

BufferedWriter The use of requires the help of FileWriter To use :

public class TestBufferedWriter {

	public static void main(String[] args) throws IOException{
		FileWriter fw = new FileWriter("file01.txt");
		BufferedWriter bw = new BufferedWriter(fw);
		int size = 0;
		while(true) {
			bw.write(" You are my eye ");
			bw.newLine();
			size++;
			if(size==8193)
				break;
			System.out.println("XXX");
		}
		System.out.println("YYY");
		bw.close();
	}
	
}

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The result is in a named “file01” Of txt File written 8193 Yes “ You are my eye ”.

• BufferedReader

BufferedReader Starting heel FileReader There is no difference in the use of , Belongs to the character input stream .

BufferedReader More efficient , Because it has a built-in length of 8192 Array of characters , That is to say 8K Array of characters . It looks like , If we read from the file , If the contents do not fill the array , Will automatically wait until we fill up , Then read from the hard disk to the memory together . The running speed of hard disk is very slow . But we can also use close() Method , Although it may not be full , But you can force it to read into memory .

It's like a supplier shipping goods to a supermarket , To save money , Generally, there are not only oneortwo , Instead, the whole car is filled before it is sent to the supermarket . But sometimes special circumstances , I can't fit it , Only one more trip . When we read , It was read one by one .

besides ,BufferedReader It also provides a way to read an entire row —— readLine() Method .

BufferedReader The use of requires the help of FileReader To use :

notes ： There are three ways to read

	public static void main(String[] args) throws IOException {
		FileReader fr = new FileReader("file01.txt");
		BufferedReader br = new BufferedReader(fr);
		
        /*
        int ch;
		while((ch=br.read())!=-1) {
			System.out.print((char)ch);
			if((char)ch == '\n')
				System.out.println();
		}
        */

		String str;
		while((str=br.readLine())!=null)
			System.out.println(str);
		
		
		/*char[] a = new char[8193];
		int len;
		while((len=br.read(a))!=-1) {
			String str = new String(a,0,len);
			System.out.println(str);
		}
		System.out.print("********");
		*/

		br.close();
	}
}

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