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Creation of a file if it does not exist; Deletion of a file if it already exists.package com.han;
import java.io.File;
/**
* Creation of a file if it does not exist;
* Deletion of a file if it already exists.
* @author han
*
*/
public class FileTest {
public static void main(String[] args) {
// TODO Auto-generated method stub
File file=new File("/home/han/Documents","word.txt");
if(file.exists()){
System.out.println(file.getPath());
file.delete();
System.out.println("文件已删除");
}else{
try{
file.createNewFile();
System.out.println("文件已创建");
}catch(Exception e){
e.printStackTrace();
}
}
}
}
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Get a specified file properties, including its name, length, and existence or if it is hidden.package com.han;
import java.io.File;
/**
* Get a specified file properties,
* including its name, length, and existence or if it is hidden.
* @author han
*
*/
public class FileTest2 {
public static void main(String[] args) {
// TODO Auto-generated method stub
File file=new File("/home/han/Documents","word.txt");
if(file.exists()){
String name=file.getName();
long length=file.length();
boolean hidden=file.isHidden(); //if the file is hidden or not.
System.out.println("文件名称： "+name);
System.out.println("文件长度： "+length);
System.out.println("该文件是隐藏文件吗？ "+hidden);
}else{
try{
System.out.println("该文件不存在");
}catch(Exception e){
e.printStackTrace();
}
}
}
}
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write a string content to a text file using a FileInputStream and FileOutputStreampackage com.han;
import java.io.*;
/**
* write a string content to a text file
* using a FileInputStream and FileOutputStream
* @author han
*
*/
public class FileTest3 {
public static void main(String[] args) {
// TODO Auto-generated method stub
File file=new File("/home/han/Documents","word.txt");
try{
FileOutputStream out=new FileOutputStream(file); //创建输出流
byte[] content_to_output="我有一只小毛驴，我从来也不骑。".getBytes();
out.write(content_to_output);
out.close(); //关闭输出流
}catch(Exception e){
e.printStackTrace();
}
try{
FileInputStream in=new FileInputStream(file); //创建输入流
byte[] content_to_input=new byte[1024];
int len=in.read(content_to_input);
in.close(); //关闭输入流
System.out.println(new String(content_to_input,0,len));
System.out.println("文件长度为： "+len);
}catch(Exception e){
e.printStackTrace();
}
}
}
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Rename a file.package com.han;
import java.io.*;
/**
* Rename a file.
* @author han
*
*/
public class FileTest4 {
public static void main(String[] args) {
/*Use to renameTo() method of the File class to complete the rename job*/
File file=new File("/home/han/Documents","word.txt");
File file_renamed=new File("/home/han/Documents","word_renamed.txt");
try{
FileOutputStream out=new FileOutputStream(file); //创建输出流
byte[] content_to_output="我有一只小毛驴，我从来也不骑。".getBytes();
out.write(content_to_output);
out.close(); //关闭输出流
file.renameTo(file_renamed);
}catch(Exception e){
e.printStackTrace();
}
/*Use the stream to copy a file to another*/
try{
FileInputStream in=new FileInputStream(file_renamed); //创建输入流
File file_copy=new File("/home/han/Documents","word_copy.txt");
FileOutputStream out_copy=new FileOutputStream(file_copy); //创建副本输出流
/*int input_byte=in.read();
while(input_byte!=-1){
out_copy.write(input_byte);
input_byte=in.read();
}*/
int input_byte=0;
while((input_byte=in.read())!=-1){ //(input_byte=in.read())!=-1 这种形式要会使用
out_copy.write(input_byte);
}
out_copy.close(); //关闭副本输出流
in.close(); //关闭输入流
System.out.println("副本文件名称为： "+file_copy.getName());
System.out.println("副本文件长度为： "+file_copy.length());
System.out.println("副本文件是隐藏文件吗？ "+file_copy.isHidden());
}catch(Exception e){
e.printStackTrace();
}
}
}
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write a string content to a specified text file. and then read it to the default command screen.package com.han; import java.io.*; /** * write a string content to a specified text file. * and then read it to the default command screen. * <p> * It used the FileReader and FileWriter, * moreover, the BufferedReader and BufferedWriter. * @author han * */ public class FileTest5 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub String[] content={"好久不见","最近好吗","常联系"}; File file=new File("/home/han/Documents","word.txt"); try { FileWriter out=new FileWriter(file); BufferedWriter bw=new BufferedWriter(out); for (int i=0;i<content.length;i++){ bw.write(content[i]); bw.newLine(); } bw.close(); out.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } try { FileReader in=new FileReader(file); BufferedReader br=new BufferedReader(in); String s=null; int i=0; while((s=br.readLine())!=null){ System.out.println("第"+(i+1)+"行： "+s); i++; } br.close(); in.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
It used the FileReader and FileWriter, moreover, the BufferedReader and BufferedWriter.
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