1 package System输入输出;
 2
 3 import java.io.ByteArrayOutputStream;
 4 import java.io.File;
 5 import java.io.FileOutputStream;
 6 import java.io.IOException;
 7 import java.io.OutputStream;
 8 import java.util.function.Consumer;
 9
10
11 public class Test {
12     public static void main(String[] args) throws IOException {
13         /*
14         try{
15             int i=3/0;
16         }catch(Exception e){
17             e.printStackTrace();
18             System.out.println(e);//输出信息红色
19             System.err.println(e);//输出信息黑色
20         }
21         */
22         //输出到屏幕
23         OutputStream out=System.out;
24         //输出到文件
25         OutputStream out2=new FileOutputStream(new File("D:"+File.separator+"test.txt"));
26         //输出到内存
27         OutputStream out3=new ByteArrayOutputStream();
28         //以上体现多态性
29         out.write("Welcom to 中国\n".getBytes());
30
31         Consumer<String> consumer=System.out::println;
32         consumer.accept("北京欢迎你！");
33     }
34 }

 1 package System输入输出;
 2
 3 import java.io.IOException;
 4 import java.io.InputStream;
 5
 6 public class Test {
 7     public static void main(String[] args) throws IOException {
 8         InputStream in=System.in;
 9         byte[] b=new byte[1024];
10         System.out.println("请输入数据：");
11         int len=in.read(b);
12         System.out.println(new String(b,0,len));
13     }
14 }

 1 package System输入输出;
 2
 3 import java.io.IOException;
 4 import java.io.InputStream;
 5
 6 public class Test {
 7     public static void main(String[] args) throws IOException {
 8         InputStream in=System.in;
 9         StringBuffer sb=new StringBuffer();
10         System.out.println("请输入数据：");
11         int tmp=0;
12         while((tmp=in.read())!=-1){
13             if(tmp=='\n')
14                 break;
15             sb.append((char)tmp);
16         }
17         System.out.println(sb);
18     }
19 }