毕向东_Java基础视频教程第20天_IO流（5~6）
第20天-05-IO流(文件列表一)
static File[] listRoots()
List the available filesystem roots.
String[] list()
Returns an array of strings naming the files and directories in the directory denoted by this abstract pathname.
String[] list(FilenameFilter filter)
Returns an array of strings naming the files and directories in the directory denoted by this abstract pathname that satisfy the specified filter.
File[] listFiles()
Returns an array of abstract pathnames denoting the files in the directory denoted by this abstract pathname.
File[] listFiles(FileFilter filter)
Returns an array of abstract pathnames denoting the files and directories in the directory denoted by this abstract pathname that satisfy the specified filter.
File[] listFiles(FilenameFilter filter)
Returns an array of abstract pathnames denoting the files and directories in the directory denoted by this abstract pathname that satisfy the specified filter.
package bxd;
import java.io.File;
public class FileDemo4 {
public static void method_1() {
File[] files = File.listRoots();
for (File file : files) {
System.out.println(file);
}
}
public static void method_2() {
File dir = new File("/Users/Eric/Desktop");
// 如果File dir传入的不是目录而是文件, 则会抛出空指针异常
for (String name : dir.list()) {
System.out.println(name);
}
}
public static void main(String[] args) {
method_2();
}
}
第20天-06-IO流(文件列表二)
package bxd; import java.io.File;
import java.io.FilenameFilter; public class FileDemo5 {
public static void method_1() {
File demoDir = new File("/Users/Eric/Desktop");
String[] names = demoDir.list(new FilenameFilter() {
@Override
public boolean accept(File dir, String name) { // accept方法的入参File dir即为File demoDir
return name.endsWith(".pdf");
}
}); for (String name : names) {
System.out.println(name);
}
} public static void method_2() {
File dir = new File("/Users/Eric/Desktop");
for (File file : dir.listFiles()) {
System.out.println(file.getName() + "::" + file.length());
}
} public static void main(String[] args) {
method_2();
}
}
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