Question

我正在尝试完成一个任务，在我的哈希映射中，我只存储实际数据存储在堆中的KV代理对象。

所以我创建了一个覆盖equals和hashcode方法的代理对象，使其与原始对象具有相同的值。

然后我测试结果并发现我无法通过原点键再次找到V.

ObjectOffHeapProxy offHeapKeyProxy = new ObjectOffHeapProxy(key);
System.out.println("key="+key+"---offHeapKeyProxy.hashCode()==key.hashCode() "+(offHeapKeyProxy.hashCode()==key.hashCode()));
System.out.println("key="+key+"---offHeapKeyProxy.equals(key) "+(offHeapKeyProxy.equals(key)));
ObjectOffHeapProxy offHeapValueProxy = new ObjectOffHeapProxy(value);
skeleton.put(offHeapKeyProxy,offHeapValueProxy);
//put into the map
System.out.println("put by proxy,try get object from the origin key is ：" + skeleton.get(key));
//can't find it again.
System.out.println("put by proxy，try get object from the proxy is"+skeleton.get(offHeapKeyProxy));
bloomFilter.add(key.hashCode());
System.out.println("put a proxy，try get object from the proxy is"+skeleton.get(offHeapKeyProxy));
//this works but it does not meet my expectation

OUTPUT就像：

key=1---offHeapKeyProxy.hashCode()==key.hashCode() true
key=1---offHeapKeyProxy.equals(key) true
put a proxy，try get object from the origin key is ：null
put a proxy，try get object from the 
proxy isxxx.yyy.ObjectOffHeapProxy@b73a019f

在我看来，哈希码是找到存储桶位置，他们将使用equals来确定它们是否相等，并且由于哈希码是相同的并且它们是等于（），为什么会这样？ / p>

供参考：

public class ObjectOffHeapProxy {

    private final ByteBuffer buff;
    public ObjectOffHeapProxy(Object actual) throws IOException {

        byte[] bytes = SerialUtil.serialize(actual);
        this.buff = ByteBuffer.allocateDirect(bytes.length);
        buff.put(bytes);
    }


    @Override
    public boolean equals(Object o) {
        return findActual().equals(o);
    }

    /**
     * actual data's hashcode
     * @return
     */
    @Override
    public int hashCode() {
        return findActual().hashCode();
    }

    public Object findActual() {
        try{
            buff.flip();
            byte[] target = new byte[buff.limit()];
            buff.get(target);
            return SerialUtil.deserialize(target);//TODO  please check
        }
        catch (IOException | ClassNotFoundException ex) {
            ex.printStackTrace();
            throw new RuntimeException(ex);
        }
    }

}

更新

正如评论指出的那样，等于破坏事物：

System.out.println("key="+key+"---offHeapKeyProxy.hashCode()==key.hashCode() "+(offHeapKeyProxy.hashCode()==key.hashCode()));
System.out.println("key="+key+"---offHeapKeyProxy.equals(key) "+(offHeapKeyProxy.equals(key)));
System.out.println("key="+key+"---key.equals(offHeapKeyProxy) "+(key.equals(offHeapKeyProxy)));  //false here!!!!

但由于我不知道要更改密钥，它们来自用户，我该如何解决？

无法通过键从hashmap获取对象具有相同的哈希码，并且两个键是equals（）

0 个答案: