方法不覆盖或从超实现方法 - 占优 [英] method does not override or implement a method from a supertype - for Override
问题描述
我环顾四周，但想不通为什么我收到错误
I have looked all around but can't figure out why I'm getting the error
错误：方法不覆盖或从超实现的方法
error: method does not override or implement a method from a supertype
这凸显了两个 @覆盖的I有一个方法（子程序？）。这里是我的 MainActivity.java - 在$ C $的C部分它在 queryBooks发生（）在方法结束 - 在 @覆盖是两个红色下划线。
This highlights the two @Overrides I have in a method (subroutine?). Here's my MainActivity.java - the part of the code it occurs in the queryBooks() method at the end - the @Overrides are both underlined red.
package com.example.batman.myapplication;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v4.view.MenuItemCompat;
//import android.support.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.ShareActionProvider;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.JsonHttpResponseHandler;
import org.json.JSONObject;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity implements View.OnClickListener, AdapterView.OnItemClickListener {
TextView mainTextView;
EditText mainEditText;
ListView mainListView;
ArrayAdapter mArrayAdapter;
// ArrayList<String> mNameList = new ArrayList<String>();
ArrayList mNameList = new ArrayList();
android.support.v7.widget.ShareActionProvider mShareActionProvider;
// This is for internet stuff
private static final String QUERY_URL = "http://openlibrary.org/search.json?q=";
// Setting up the storage of data
private static final String PREFS = "prefs";
private static final String PREF_NAME = "name";
SharedPreferences mSharedPreferences;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 1. Access the TextView defined in layout XML
// and then set its text
mainTextView = (TextView) findViewById(R.id.main_textview);
// mainTextView.setText("Set in Java!");
Button mainButton;
mainButton = (Button) findViewById(R.id.main_button);
mainButton.setOnClickListener(this);
// 3. Access the EditText defined in layout XML
mainEditText = (EditText) findViewById(R.id.main_edittext);
// 4. Access the ListView
mainListView = (ListView) findViewById(R.id.main_listview);
// Create an ArrayAdapter for the ListView
mArrayAdapter = new ArrayAdapter(this,
android.R.layout.simple_list_item_1,
mNameList);
// Set the ListView to use the ArrayAdapter
mainListView.setAdapter(mArrayAdapter);
// 5. Set this activity to react to list items being pressed
mainListView.setOnItemClickListener(this);
// 7. Greet the user, or ask for their name if new
displayWelcome();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu.
// Adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
// Access the Share Item defined in menu XML
MenuItem shareItem = menu.findItem(R.id.menu_item_share);
// Access the object responsible for
// putting together the sharing submenu
if (shareItem != null) {
mShareActionProvider = (ShareActionProvider) MenuItemCompat.getActionProvider(shareItem);
}
// Create an Intent to share your content
setShareIntent();
return true;
}
private void setShareIntent() {
if (mShareActionProvider != null) {
// create an Intent with the contents of the TextView
Intent shareIntent = new Intent(Intent.ACTION_SEND);
shareIntent.setType("text/plain");
shareIntent.putExtra(Intent.EXTRA_SUBJECT, "Android Development");
shareIntent.putExtra(Intent.EXTRA_TEXT, mainTextView.getText());
// Make sure the provider knows
// it should work with that Intent
mShareActionProvider.setShareIntent(shareIntent);
}
}
@Override
public void onClick(View v) {
// // Take what was typed into the EditText
// // and use in TextView
// mainTextView.setText(mainEditText.getText().toString() + ".");
//
// // Also add that value to the list shown in the ListView
// mNameList.add(mainEditText.getText().toString());
// mArrayAdapter.notifyDataSetChanged();
// // 6. The text you'd like to share has changed,
// // and you need to update
// setShareIntent();
//
// if(v == mainEditText) {
// mainEditText.setText("");
// }
// 9. Take what was typed into the EditText and use in search
// (the above is commented out, per tutorial part 3 - this takes its place as input
queryBooks(mainEditText.getText().toString());
// mainEditText.setText("");
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// Log the item's position and contents
// to the console in Debug
Log.d("My Application", position + ": " + mNameList.get(position));
}
public void displayWelcome() {
// Access the device's key-value storage
mSharedPreferences = getSharedPreferences(PREFS, MODE_PRIVATE);
// Read the user's name,
// or an empty string if nothing found
String name = mSharedPreferences.getString(PREF_NAME, "");
if (name.length() > 0) {
// If the name is valid, display a Toast welcoming them
Toast.makeText(this, "Welcome back, " + name + "!", Toast.LENGTH_LONG).show();
} else {
// otherwise, show a dialog to ask for their name
AlertDialog.Builder alert = new AlertDialog.Builder(this);
alert.setTitle("Hello!");
alert.setMessage("What is your name?");
// Create EditText for entry
final EditText input = new EditText(this);
alert.setView(input);
// Make an "OK" button to save the name
alert.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
// Grab the EditText's input
String inputName = input.getText().toString();
// Put it into memory (don't forget to commit!)
SharedPreferences.Editor e = mSharedPreferences.edit();
e.putString(PREF_NAME, inputName);
e.commit();
// Welcome the new user
Toast.makeText(getApplicationContext(), "Welcome, " + inputName + "!", Toast.LENGTH_LONG).show();
}
});
// Make a "Cancel" button
// that simply dismisses the alert
alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {}
});
alert.show();
}
}
// Internet stuff
private void queryBooks(String searchString) {
// Prepare your search string to be put in a URL
// It might have reserved characters or something
String urlString = "";
try {
urlString = URLEncoder.encode(searchString, "UTF-8");
} catch (UnsupportedEncodingException e) {
// if this fails for some reason, let the user know why
e.printStackTrace();
Toast.makeText(this, "Error: " + e.getMessage(), Toast.LENGTH_LONG).show();
}
// Create a client to perform networking
AsyncHttpClient client = new AsyncHttpClient();
// Have the client get a JSONArray of data
// and define how to respond
client.get(QUERY_URL + urlString,
new JsonHttpResponseHandler() {
@Override // THIS METHOD DOES NOT OVERRIDE METHOD FROM ITS SUPERCLASS ??
public void onSuccess(JSONObject jsonObject) {
// Display a "Toast" message
// to announce your success
Toast.makeText(getApplicationContext(), "Success!", Toast.LENGTH_LONG).show();
// 8. For now, just log results
Log.d("omg android", jsonObject.toString());
}
@Override // THIS METHOD DOES NOT OVERRIDE METHOD FROM ITS SUPERCLASS ??
public void onFailure(int statusCode, Throwable throwable, JSONObject error) {
// Display a "Toast" message
// to announce the failure
Toast.makeText(getApplicationContext(), "Error: " + statusCode + " " + throwable.getMessage(), Toast.LENGTH_LONG).show();
// Log error message
// to help solve any problems
Log.e("omg android", statusCode + " " + throwable.getMessage());
}
});
}
} // end class
（对于它的价值，我在下面的这个教程）。
感谢您的任何想法！
推荐答案
的问题是什么错误消息说：该方法不覆盖或实现从超的方法。您注释与覆盖注解，但是，没有方法的具有相同签名（即参数的），可以在父（找到 JsonHtt presponseHandler ）。
The problem is what the error message is saying: "the method does not override or implement a method from a supertype". You annotated both methods with the Override annotation, however, no method with the same signature (i.e. the parameters) can be found in the supertype (JsonHttpResponseHandler).
如果你看看在的 JsonHtt presponseHandler 的文档，你可以看到所有可用的的onSuccess（...）和 onFailure处（。 ..）方法。
If you take a look at the documentation of JsonHttpResponseHandler, you can see all the available onSuccess(...) and onFailure(...) methods.
下面是你的code的工作版本（注意在方法签名改变）：
Here is the working version of your code (note that changes in the method signatures):
client.get(QUERY_URL + urlString,
new JsonHttpResponseHandler() {
@Override
public void onSuccess(int statusCode, org.apache.http.Header[] headers, JSONObject jsonObject) {
// Display a "Toast" message
// to announce your success
Toast.makeText(getApplicationContext(), "Success!", Toast.LENGTH_LONG).show();
// 8. For now, just log results
Log.d("omg android", jsonObject.toString());
}
@Override
public void onFailure(int statusCode, org.apache.http.Header[] headers, Throwable throwable, JSONObject error) {
// Display a "Toast" message
// to announce the failure
Toast.makeText(getApplicationContext(), "Error: " + statusCode + " " + throwable.getMessage(), Toast.LENGTH_LONG).show();
// Log error message
// to help solve any problems
Log.e("omg android", statusCode + " " + throwable.getMessage());
}
});
请注意，从在Android 6.0（API级别23）在Apache库（org.apache.http。*）起不再提供。如果您希望继续使用，请参见行为更改以获取更多信息。
Note that starting from Android 6.0 (API level 23) the Apache library (org.apache.http.*) is not available anymore. If you want to continue using that, see Behavior Changes for more information.
一些个人意见：我不推荐使用的异步HTTP库的，因为它是建立在顶部的过时的（和API级别23，删除）的Apache HttpClient的，这已表现不佳相比， HttpURLConnection类。从Android开发报价约 HttpURLConnection类：
Some personal opinion: I wouldn't recommend using the Asynchronous HTTP Library as it's built on top of the obsolete (and from API level 23, removed) Apache HttpClient, which has poor performance compared to HttpURLConnection. Quote from the Android developers about HttpURLConnection:
此API是更有效，因为它减少了通过透明的COM pression和响应缓存网络的使用，并最大限度地减少功耗。
This API is more efficient because it reduces network use through transparent compression and response caching, and minimizes power consumption.
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