foreword

Hello everyone, this is my overview Victoday , I hope you like itJava中的读文件，文件的创建，写文件

Schematic

read file

public static void read(String path,String filename){
 try{
  int length=0;
  String str="";
  byte buffer[] = new byte[10];
  FileInputStream fis = new FileInputStream(new File(path,filename));
  while((length=fis.read(buffer,0,buffer.length))!=-1){
  str+=new String(buffer,0,length);
  }
  System.out.println(str);
  fis.close();
  }catch(FileNotFoundException e){
   System.out.println("文件不存在");
   }catch(IOException e){
    e.printStackTrace();
  }
}

file creation

public class FileDemo{
 public static void createFolder(String path){
  File folder=new File(path);
  if(folder.exists()){
   System.out.println("文件夹已存在!");
  }else{
   folder.mkdir();
  }
 }
  public static void createFile(String path,String filename){
  File file=new File(path,filename);
  if(file.exists()){
   System.out.println("文件已存在!");
   System.out.println(file.length());
   }else{
    try{
     file.createNewFile();
    }catch(IOException e){
     System.out.println("文件创建失败");
    }
  }
 }
  public static void main(String[] args){
   FileDemo.createFolder("c:/text");
   FileDemo.createFile("c:/text","1.txt");
  }
}

write file

public static void write(String path,String filename){
 try{
  String str="123456789";
  byte b[] = str.getBytes();
  FileOutputStream fos=new FileOutputStream(new File(path,filename));
  fos.write(b);
  }catch(FileNotFoundException e){
   System.out.println("文件不存在");
  }catch(IOException e){
   System.out.println("写文件失败");
  }
}

Get the properties of a file

String getName()

boolean canRead ()
boolean canWrite ()

boolean exits()

boolean isFile()
boolean isDirectory()
boolean isHidden()

Relevant knowledge and technology

boolean mkdir(): create a directory, return true if successful

boolean createNewFile(): create a file

boolean delete(): delete a file

Classification of streams in Java

The movement direction of the flow: divided into two types: input flow and output flow
Stream data type: divided into byte stream and character stream

All input stream classes are abstract classes, and all output stream classes are abstract classes.

Bytes: InputStream, OutputStream
Characters: Reader class, Writer class

Read data from the input stream:

FileInputStream vFile=new FileInputStream("File1.dat");
vFile.read();
vFile.close();

output stream:

FileOutputStream oFile=new FileOutputStream("File2.dat");
oFile.write(vFile.read()):
oFile.close();

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Summarize

This article talks about reading files, creating files, and writing files in Java. If you have a better understanding, welcome to communicate
Positioning: sharing Android& Javaknowledge points, if you are interested, you can continue to pay attention

Reading files, creating files, writing files in Java