Java中的文件 setLastModified() 方法及示例
setLastModified()方法是 File 类的一部分。该函数设置文件或目录的最后修改时间。该函数以毫秒为单位设置文件的最后修改值。
函数签名:
public boolean setLastModified(long time)
函数语法:
file.setLastModified(time)
参数:此函数接受一个长值作为参数,表示新的最后修改时间。
返回值:该函数返回一个布尔值,表示是否设置了新的最后修改时间。
例外;此方法引发以下异常:
- 如果不允许该函数对文件进行写访问,则出现SecurityException
- 如果参数为负,则IllegalArgumentException
下面的程序将说明 setLastModified()函数的使用:
示例 1:我们将尝试更改 f: 目录中现有文件的最后修改时间。
Java
// Java program to demonstrate the
// use of setLastModified() function
import java.io.*;
public class solution {
public static void main(String args[])
{
// try-catch block to handle exceptions
try {
// Create a file object
File f = new File("f:\\program.txt");
// The new last modified time
long time = 100000000;
// Check if the last modified time
// can be set to new value
if (f.setLastModified(time)) {
// Display that the last modified time
// is set as the function returned true
System.out.println("Last modified time is set");
}
else {
// Display that the last modified time
// cannot be set as the function returned false
System.out.println("Last modified time cannot be set");
}
}
catch (Exception e) {
System.err.println(e.getMessage());
}
}
}
Java
// Java program to demonstrate the
// use of setLastModified() function
import java.io.*;
public class solution {
public static void main(String args[])
{
// try-catch block to handle exceptions
try {
// Create a file object
File f = new File("f:\\program1.txt");
// The new last modified time
long time = 100000000;
// Check if the last modified time
// can be set to new value
if (f.setLastModified(time)) {
// Display that the last modified time
// is set as the function returned true
System.out.println("Last modified "
+ "time is set");
}
else {
// Display that the last modified time
// cannot be set as
// the function returned false
System.out.println("Last modified time"
+ " cannot be set");
}
}
catch (Exception e) {
System.err.println(e.getMessage());
}
}
}
输出:
Last modified time is set
示例 2:我们将尝试更改 f: 目录中不存在的文件的最后修改时间。
Java
// Java program to demonstrate the
// use of setLastModified() function
import java.io.*;
public class solution {
public static void main(String args[])
{
// try-catch block to handle exceptions
try {
// Create a file object
File f = new File("f:\\program1.txt");
// The new last modified time
long time = 100000000;
// Check if the last modified time
// can be set to new value
if (f.setLastModified(time)) {
// Display that the last modified time
// is set as the function returned true
System.out.println("Last modified "
+ "time is set");
}
else {
// Display that the last modified time
// cannot be set as
// the function returned false
System.out.println("Last modified time"
+ " cannot be set");
}
}
catch (Exception e) {
System.err.println(e.getMessage());
}
}
}
输出:
Last modified time cannot be set
这些程序可能无法在在线 IDE 中运行。请使用离线IDE并设置文件的父文件