正在将 Closeable 的新实例分配给之前创建的实例，关闭之前的实例吗？
Is allocating new instance of Closeable to previously created instance, closing previous?
例如Scannerclass，它实现了Closeable接口：
Scanner sc = new Scanner(...);
sc.//do smthing
sc = new Scanner(...); <- is previous Scanner closed? Does it create memory leak?
sc.//do smthing
sc.close();
不，除非您显式调用 sc.close()，或将其范围限定在 try-with-resources block, there are no guarantees it will be closed. Some classes might have a finalizer or an associated Cleaner，但这些非常不可靠（例如，您永远不知道它们何时或什至是否会被调用）。
例如Scannerclass，它实现了Closeable接口：
Scanner sc = new Scanner(...);
sc.//do smthing
sc = new Scanner(...); <- is previous Scanner closed? Does it create memory leak?
sc.//do smthing
sc.close();
不，除非您显式调用 sc.close()，或将其范围限定在 try-with-resources block, there are no guarantees it will be closed. Some classes might have a finalizer or an associated Cleaner，但这些非常不可靠（例如，您永远不知道它们何时或什至是否会被调用）。