打印IO流

package file;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.PrintStream;
import java.util.Scanner;

import org.junit.Test;

/*
1.System中的IO流
System.in:InputStream
System.out:PrintStream,默认打印到控制台
System.err:PrintStream

PrintStream:
(1)不会抛异常
（2）自动刷新
其他IO流，可以手动刷新

*/


public class test12 {
    
    
    @Test
    public void test3() throws FileNotFoundException {
        System.setIn(new FileInputStream("resource/1.txt"));
        Scanner input=new Scanner(System.in);
        System.out.println(input.nextLine());
        System.out.println(input.nextLine());
        
        input.close();
        
        
    }
    
    @Test
    public void test2() throws FileNotFoundException {
        System.setOut(new PrintStream("resource/1.txt"));
        System.out.println("hello");
        System.out.println("java");
        
        
    }
    @Test
    public void test1() {
        System.out.println();
        //System.out.print(); 必须有参数
        
    }

}

package file;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Scanner;

import org.junit.Test;

public class test11 {
    
    @Test
    public void test01() {
        Scanner s=new Scanner(System.in);
        System.out.println("input: ");
        String str=s.next();
        System.out.println("input: "+str);
    }
    
    @Test
    public void test02() throws FileNotFoundException {
        Scanner input=new Scanner(new FileInputStream("resource/1.txt"));
        while(input.hasNextLine()) {
            String line=input.nextLine();
            System.out.println(line);
        }
    }

}