IO stream system and FileReader, filewriter

package IOStream;

import org.junit.Test;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;

public class FileReadWriter {


//
    @Test
    public void testFileReader()  {
//        fr It needs to be declared in advance 
        FileReader fr = null;
//        1. Instantiation File Class object , Indicates the file to be operated on 
        try {
            File file1 = new File("hello.txt");

//        2. Provide specific flow ：( Find the pipe )
            fr = new FileReader(file1);

//        3. Reading in data 
//      read() Returns a character read in , use int  When accepting ASCII code , If it reaches the end, it returns -1
//         The way 1：
//        int data = fr.read();
//        while(data != -1){
//            System.out.print((char) data);
//            data = fr.read();
//        }
//         The way 2：
            int data ;
            while((data = fr.read())!= -1){
                System.out.print((char)data);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if(fr!=null){
                    fr.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

        }


//        4. Stream closing operation 
    }
}

read() Overload method of ：read(char cbuffer[])  Returns the number of characters read

//     Yes read() An upgrade of the operation method ： Use read Overloading methods 
    //        read(char[])  Returns the number of characters read in each time , such as helloworld123!, Returns the 5 5 4 -1


    @Test
    public void testFileReader2()  {
//        1.File Class instantiation 
        FileReader fr = null;
        try {
            File file = new File("hello.txt");

//        2. Instantiation of a stream 
            fr = new FileReader(file);
//        3. Read in operation 
//        read(char[])  Returns the number of characters read in each time , such as helloworld123!, Returns the 5 5 4 -1
            char[] cbuffer = new char[5];
            int len ;
            while((len = fr.read(cbuffer))!=-1){
                for(int i = 0 ; i < len; i++){
                    System.out.print(cbuffer[i]);
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
//        4. Resources to shut down 
                if (fr != null) {
                    fr.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }

FileWriter Explanation ：

package IOStream;
/*
 Write data from memory to hard disk 
 explain ：
1. Output operation File The object may not exist , This file will be created automatically 
                     If exist , In the constructor append: choice true To continue adding ,false To overwrite the original file 
                    FileWriter(file,true/false)
2.
 */
import org.junit.Test;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

public class FileWriterTest {
    @Test
    public void testFileWriter() throws IOException {
//        1. Provide File object , Indicates the file written out 
        File file1 = new File("hello1.txt");

//        2. Provide FileWriter object , For writing data 
        FileWriter fw = new FileWriter(file1,false);

//        3. Written operations 
        fw.write("i have a dream!\n");
        fw.write("you need to have a dream!");

//        4. The closure of streaming resources 
        fw.close();
    }
}