Javaio流学习

创建文件的三种方式：

1.package yjtest.demo;

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

public class testcreate {
public static void main(String[] args) throws IOException {
File file = new File("D:\\test");

file.createNewFile();
}
}
2.package yjtest.demo;

import javafx.scene.Parent;

import javax.swing.*;
import java.io.File;
import java.io.IOException;

public class testcreate2 {
public static void main(String[] args) {
File parentFile = new File("D:\\");
String fileName = "file2.txt";
File file = new File(parentFile,fileName);
try{
file.createNewFile();
System.out.println("文件二创建成功");
} catch (IOException e) {
e.printStackTrace();
}
}
}

3.package yjtest.demo;

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

public class testcreate3 {
public static void main(String[] args) {
String parentPath = "D:\\";
String filePath = "file3.txt";
File file = new File(parentPath,filePath);
try{
file.createNewFile();
System.out.println("文件三创建成功");
} catch (IOException e) {
e.printStackTrace();
}
}
}

文件信息的查询：

package yjtest.demo;

import java.io.File;

public class testcheck {
    public static void main(String[] args) {
        File file = new File("D:\\file1.txt");
        System.out.println("文件名称："+file.getName());
        System.out.println("文件绝对路径："+file.getAbsolutePath());
        System.out.println("文件父目录："+file.getParent());
        System.out.println("文件大小（字节）："+file.length());
        System.out.println("文件是否存在："+file.exists());
        System.out.println("是否是文件："+file.isFile());
        System.out.println("是否是目录："+file.isDirectory());
    }
}
4.文件夹的创建：
package yjtest.demo;

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

public class testcreate {
    public static void main(String[] args) throws IOException {
        File file = new File("D:\\test");
        file.mkdir();
    }
}
5.Scanner与Ptintln：

1.package yjtest.demo;

import java.util.Scanner;

public class testjavaio {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String str = input.next();
        System.out.println(str);
        System.out.println("hello world");
    }
}

2.package yjtest.demo;

import java.util.Scanner;

public class testkeyin {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("请输入一个double类型的数：");
        double d = input.nextDouble();
        System.out.println(d);
        System.out.println("请输入一个int类型的数");
        int i = input.nextInt();
        System.out.println(i);
        System.out.println("请输入一个string类型的数");
        String s = input.next();
        System.out.println(s);

    }
}