java - 找不到 WeakReference 符号

Question

已经导入弱引用但编译器找不到符号，怎么了？ DumpReceiver.java 中存在内存泄漏我认为弱引用可能会在使用后释放？

import java.lang.ref.WeakReference;

Receiver r = new DumpReceiver(System.out);
WeakReference<Receiver> wr = new WeakReference<DumpReceiver>(r);


MidiInDump.java:64: cannot find symbol
symbol  : constructor WeakReference(javax.sound.midi.Receiver)
location: class java.lang.ref.WeakReference<DumpReceiver>
                WeakReference<Receiver> wr = new WeakReference<DumpReceiver>(r);

                                             ^

Answer 1

仔细查看错误消息。这不是在谈论类(class)(它发现这很好)。它在谈论构造函数。它找不到采用 javax.sound.midi.Receiver 的构造函数关于类型的参数 WeakReference<DumpReceiver> .查看 WeakReference<T> 的 JavaDoc有一个构造函数接受类型为 T 的参数.

您正在尝试创建一个 WeakReference<DumpReceiver>但尝试传入类型为 javax.sound.midi.Receiver 的对象.您要么需要创建一个 WeakReference<Receiver>相反或更改变量 r类型为 DumpReceiver .