auto commit

notes/Java IO.md

@@ -69,16 +69,17 @@ public static void listAllFiles(File dir) {
 
 ```java
 public static void copyFile(String src, String dist) throws IOException {
-
     FileInputStream in = new FileInputStream(src);
     FileOutputStream out = new FileOutputStream(dist);
+
     byte[] buffer = new byte[20 * 1024];
+    int cnt;
 
     // read() 最多读取 buffer.length 个字节
     // 返回的是实际读取的个数
     // 返回 -1 的时候表示读到 eof，即文件尾
-    while (in.read(buffer, 0, buffer.length) != -1) {
-        out.write(buffer);
+    while ((cnt = in.read(buffer, 0, buffer.length)) != -1) {
+        out.write(buffer, 0, cnt);
     }
 
     in.close();