IO流---打印流

Posted 2020-12-25 java-jiangtao-home

package 打印流;

import java.io.FileNotFoundException;
import java.io.PrintWriter;

public class Demo1 {
    public static void main(String[] args) {
        PrintWriter pw = null;
        try {
             pw = new PrintWriter("c.txt");
             pw.print("aaa");
             pw.print(‘c‘);
             pw.print(true);
             pw.println(1);
             pw.flush();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            if(pw!=null) {
                pw.close();
            }
        }
        
        
    }
}

package 打印流;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;

public class Demo2 {
    public static void main(String[] args) {
        PrintWriter pw = null;
        BufferedReader bw = null;
        try {
             pw = new PrintWriter(System.out);
            //自动刷新
             pw = new PrintWriter(System.out,true);
             bw = new BufferedReader(new FileReader("a.txt"));
             String line = null;
             while((line = bw.readLine()) != null) {
                 pw.println(line);
//                 自动刷新就不用flush了
                 //pw.flush();
             }
             
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();}
        finally {
            if(bw!=null) {
                pw.close();
            }
            if(pw!=null) {
                pw.close();
            }
        }
        
        
    }
}

package 打印流;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;

public class Demo3 {
    public static void main(String[] args) {
        PrintWriter pw = null;
        BufferedReader bw = null;
        try {
            // pw = new PrintWriter(System.out);
            //自动刷新
             /**
              * PrintFile里面的参数如果是new FileWriter("")，就是往文件里面打印东西，如果是
              * System.out就是往控制台打印东西
              */
             pw = new PrintWriter(new FileWriter("student.txt"),true);
             bw = new BufferedReader(new FileReader("a.txt"));
             String line = null;
             while((line = bw.readLine()) != null) {
                 pw.println(line);
//                 自动刷新就不用flush了
                 //pw.flush();
             }
             
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();}
        finally {
            if(bw!=null) {
                pw.close();
            }
            if(pw!=null) {
                pw.close();
            }
        }
        
        
    }
}