声明InputStream

Question

我正在学习android，学习Java，但对编程并不陌生(使用Eclipse)。我试图在一个方法中执行这样的示例代码：

private void dummy() {
    try {
        URL url = new URL(quakeFeed);
        URLConnection connection;
        connection = url.openConnection();
        HttpURLConnection httpconnection = (HttpURLConnection)connection;
        int responseCode = httpconnection.getResponseCode();
        if(responseCode == HttpURLConnection.HTTP_OK)
            InputStream inp = new BufferedInputStream(httpconnection.getInputStream());
    }
...
}

假设定义了所有其他语法和变量。我得到以下错误：

无法将

InputStream`‘解析为变量。

即使在导入java.io.InputStream;之后，这也是很奇怪的。

如果我在方法之外声明InputStream，即

InputStream inp;
private void dummy() {
    try {
        URL url = new URL(quakeFeed);
        URLConnection connection;
        connection = url.openConnection();
        HttpURLConnection httpconnection = (HttpURLConnection)connection;
        int responseCode = httpconnection.getResponseCode();
        if(responseCode == HttpURLConnection.HTTP_OK)
        // Changed
            inp = new BufferedInputStream(httpconnection.getInputStream());
    }
    ...
}

我很好奇为什么InputStream的本地声明不能被解析，但是全局声明是被解决的。

Answer 1

if语句后面跟着一条语句。变量的声明需要一个块来代替。如果允许您在那里声明一个变量，它将没有可见的作用域，也没有用途。

这应该是可行的：

if(responseCode == HttpURLConnection.HTTP_OK)
{ /* Note the brace to start a block! */
  InputStream inp = new BufferedInputStream(httpconnection.getInputStream());
  /* Now use the stream within the block. */
  ...
}