我是 android studio 的新手,想要更多东西。实际上,我试图将从 onCreateMethod 中的微调器获得的字符串传递给 onPostExecute 函数。我将非常感谢您的帮助。下面是我的代码。
我尝试创建一个名为 First 的全局变量,并存储来自 spinner 的字符串并将其传递给 onPostExecute 函数。
public class Convert extends AppCompatActivity implements LocationListener
{
Spinner dropdown;
Button btn;
String text;
String first;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_convert);
dropdown = (Spinner) findViewById(R.id.spinner1);
btn = (Button)findViewById(R.id.btn);
String[] items = new String[]{"United States,USD", "Nepal,NPR", "Bangladesh,BDT","Brazil,BRL"};
ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, items);
dropdown.setAdapter(adapter);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
text = dropdown.getSelectedItem().toString();
first = text.substring(text.length()-3);
Log.i("her", first);
}
});
new DownloadTask().execute("http://openexchangerates.org/api/latest.json?
app_id=XXXXXXXXXX");
}
public class DownloadTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... urls) {
String result = "";
URL url;
HttpURLConnection httpURLConnection = null;
try {
url = new URL(urls[0]);
httpURLConnection = (HttpURLConnection) url.openConnection();
InputStream in = httpURLConnection.getInputStream();
InputStreamReader reader = new InputStreamReader(in);
int data = reader.read();
while (data != -1) {
char counter = (char) data;
result += counter;
data = reader.read();
}
return result;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
try{
JSONObject jsonObject = new JSONObject(result);
JSONObject curr = jsonObject.getJSONObject("rates");
String npr = curr.getString(first);
Log.i("money", npr );
} catch (JSONException e) {
e.printStackTrace();
}
}
}
我想要的是首先在 onPostExecute 函数上传递字符串。
最佳答案
当您调用 DownloadTask
时,asyncTask 会通过方法execute 触发,只需通过他传递参数即可。示例:
如何传递url
new DownloadTask().execute("url for download");
如何接收url
protected String doInBackground(String... urls) {
String url = urls[0]; // url for download
}
您还可以发送参数数组。另外要小心 AsyncTask
,不要传递上下文/ View 变量,它可能会导致内存泄漏,read docs .
关于java - 我想将从字符串中获取的字符串传递给 onPostExecute 方法,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54315444/