JAVA 新手入门

Scanner scan=new Scanner(System.in);	//这里先是创建一个Scanner对象
scan.next()								//从键盘输入，返回一个字符串
scan.nextInt()							//从键盘输入，返回一个int型的数据
										//同理，还有各种类型，可以通过IDEA的提示，来一一查询

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class IO_copy_File { 
   
//别忘了要在main函数出添加抛出IOExcpetion异常
    public static void main(String[] args)throws IOException
    { 
   
        long start=System.currentTimeMillis();													//这个用来记录当前的毫秒值
        FileInputStream fip=new FileInputStream("C:\\Users\\zzz\\Desktop\\活动2.jpg");			//这里定义了文件输入流的路径
        FileOutputStream fop=new FileOutputStream("D:\\test.jpg");			//定义了文件输出流的路径
        byte[] b=new byte[1024];											//通过字节数组来传递
        int len;
        while((len=fip.read(b))!=-1)										//fip.read(b)是一次性往b数组内读入有效字节，具体多少个字节由len来计数，若无了，则len为-1，也就是已经复制完毕
        { 
   
            fop.write(b,0,len);												//同理，这里就是往目标位置写入
        }
        fip.close();														//复制完毕后要记得关闭流，以节约资源
        fop.close();
        long end=System.currentTimeMillis();
        System.out.println("复制文件共耗时："+(end-start)+"秒");
    }
}

import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class IO_File_Write_Read { 
   
    public static void main(String[] args)throws IOException
    { 
   
        FileReader fr=new FileReader("C:\\Users\\zzz\\Desktop\\1.txt");
        FileWriter fw=new FileWriter("d:\\2.txt");
        char[] a=new char[1024];
        int len;
        while((len=fr.read(a))!=-1)
        { 
   
            fw.write(a,0,len);
            System.out.println(new String(a,0,len));
        }
        fr.close();
        fw.close();
    }
}

public class Main { 
   
    public static void main(String[] args) { 
   
        Thread_son1 t1=new Thread_son1();
        t1.start();							//注意：开启线程是start()方法
        for (int i = 0; i < 50; i++) { 
   
            System.out.println("main:"+i);
        }
    }
}

public class Thread_son1 extends Thread{ 
   
    public Thread_son1(){ 
   }
    public Thread_son1(String name){ 
   
        super(name);
    }
    @Override
    public void run(){ 
   
        for(int i=0;i<50;i++){ 
   
            System.out.println("Thread_son1:"+i);
        }
    }
}

public class Main_maipiao { 
   
    public static void main(String[] args) { 
   
        piao m1=new piao();
        Thread one=new Thread(m1);
        Thread two=new Thread(m1);
        Thread three=new Thread(m1);
        one.setName("窗口一");
        two.setName("窗口二");
        three.setName("窗口三");
        one.start();
        two.start();
        three.start();
    }
}

public class piao implements Runnable{ 
   
    private  int count=100;
    @Override
    public void run() { 
   
        while (true){ 
   
            synchronized (this){ 
   
                if(count<=0) break;
                System.out.println(Thread.currentThread().getName()+"正在出售第"+count+"张票");
                count--;
            }
            try { 
   
                Thread.sleep(1000);
            } catch (InterruptedException e) { 
   
                e.printStackTrace();
            }
        }
    }
}