我在这里很困惑。我正在准备 SCJP,我写了一个小递归来检查 BufferedWriter 内存分配 before|after flush() & close() 方法。请看下面的代码块,我刚刚将我的桌面文件写入了一个文本文件。
import java.io.*;
public class Myexception{
private static String lvl = "";
static BufferedWriter bw;
private static File source = new File("C:\\Users\\"+System.getProperty("user.name")+"\\Desktop\\New folder\\myTest.txt");
public static void main(String[] args) throws IOException {
Runtime rt = Runtime.getRuntime();
System.out.println("Free memory before recursive: " + rt.freeMemory());
bw = new BufferedWriter(new FileWriter(source));
checkFiles(new File("C:\\Users\\"+System.getProperty("user.name")+"\\Desktop"), 0);
System.out.println("Memory after recursive: " + rt.freeMemory());
bw.flush();
bw.close();
lvl = null;
System.out.println("Memory after clean up: " + rt.freeMemory());
}
static void checkFiles(File file, int level) throws IOException{
if(!file.exists()){
System.out.println("File doesnt exist: " + file.getName() + file.getPath());
return;
}
for(String s:file.list()){
if(new File(file.getPath() + "\\" + s).isDirectory()){
bw.newLine();
bw.write(lvl + "Directory: " + s);
lvl += " ";
checkFiles(new File(file.getPath() + "\\" + s), level+1);
}else{
bw.newLine();
bw.write(lvl + "File: " + s);
}
}
}
}
输出很好,但我不明白,flush()和close()之前的空闲内存与flush()和close()之后的空闲内存相同。请看我的输出:
Free memory before recursive: 126150232
Memory after recursive: 104461304
Memory after clean up: 104461304
我检查了现有的主题,但找不到确切的解释。我期待在 bw.close() 之后我会有更多的可用内存。
谢谢