Question

我正在尝试通过异步任务发布到服务器，并在将Hashmap转换为String时发生此错误。这个错误是什么意思。它为什么会出现？我该如何解决这个问题？这是我的代码：

public class NetworkAccess extends AsyncTask<HashMap<String,String>,Void,String> {
private URL url;
private HttpURLConnection con;
private OutputStream os;

@Override
protected String doInBackground(HashMap<String, String>... vals) {
    String response = "";

    try {
        url = new URL("http://192.168.0.3/chow/user-login.php");
        con = (HttpURLConnection) url.openConnection();
        con.setRequestMethod("POST");
        con.setDoOutput(true);
        con.setConnectTimeout(1000);
        OutputStream os = con.getOutputStream();
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os,"UTF-8"));
        String pd = getPostDataString(vals); //Error
        writer.write(pd);
        writer.flush();
        writer.close();
        BufferedInputStream bis = new BufferedInputStream(con.getInputStream());
        BufferedReader r = new BufferedReader(new InputStreamReader(bis));
        StringBuilder total = new StringBuilder();
        String line;
        while ((line = r.readLine()) != null) {
            total.append(line);
        }
        response = total.toString();
    }
    catch (Exception e){
        e.printStackTrace();

    return response;
}

@Override
protected void onPostExecute(String s) {
    super.onPostExecute(s);
}
private String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException {
    StringBuilder result = new StringBuilder();
    boolean first = true;
    for(Map.Entry<String, String> entry : params.entrySet()){
        if (first)
            first = false;
        else
            result.append("&");

        result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
        result.append("=");
        result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
    }

    return result.toString();
}

}

Answer 1

你得到的错误表明你直接尝试创建一个HashMap数组，而不是只创建String of String，迭代Collection并将HashMap对象插入其中。

在getPostDataString（）内，将代码更改为

StringBuilder [] sb = new StringBuilder [100];

并检查它是否有效。

getPostDataString（java.util.HashMap <java.lang.string，java.lang.string>）无法应用于（java.util.HashMap <java.lang.string，java.lang.string> []）

1 个答案: