Java中的文件 setReadOnly() 方法及示例
setReadOnly()方法是 File 类的一部分。 setReadOnly()函数标记指定的文件或目录,以便只允许对该文件或目录进行读取操作。
函数签名:
public boolean setReadOnly()
句法:
file.setReadOnly()
参数:该函数不需要任何参数。
返回值:函数返回布尔数据类型。如果文件对象可以设置为只读,则该函数返回 true,否则返回 false。
异常:如果该方法不允许对文件进行写访问,则此方法将引发SecurityException
下面的程序将说明 setReadOnly()函数的使用:
示例 1:将现有文件“F:\program.txt”设置为只读
// Java program to demonstrate
// the use of File.setReadOnly() method
import java.io.*;
public class GFG {
public static void main(String args[])
{
// create an abstract pathname (File object)
File f = new File("F:\\program.txt");
// check if the file object
// can be set as Read Only or not
if (f.setReadOnly()) {
// display that the file object
// is set as Read Only or not
System.out.println("File set as Read Only");
}
else {
// display that the file object
// cannot be set as Read Only or not
System.out.println("File cannot be set"
+ " as Read Only");
}
}
}
输出:
File set as Read Only
示例 2:将不存在的文件“F:\program1.txt”设置为只读
// Java program to demonstrate
// the use of File.setReadOnly() method
import java.io.*;
public class GFG {
public static void main(String args[])
{
// create an abstract pathname (File object)
File f = new File("F:\\program1.txt");
// check if the file object
// can be set as Read Only or not
if (f.setReadOnly()) {
// display that the file object
// is set as Read Only or not
System.out.println("File set as Read Only");
}
else {
// display that the file object
// cannot be set as Read Only or not
System.out.println("File cannot be set"
+ " as Read Only");
}
}
}
输出:
File cannot be set as Read Only
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