执行Android默认布局活动的LoginActivity.java时出错

我已经在Android Studio的新活动下使用内置模板创建了一个LoginActivity。我使用了一个带有PHP脚本的SqlDatabase，用于使用post方法进行登录。当我执行此代码时，我得到2个错误：

1） 错误：（370，9）错误：方法不重写或实现超类型中的方法

C:\Users\Chethan\AndroidStudioProjects\CleanMyChennai\app\src\main\java\com\example\Chethan\myapplication\LoginPage.java

2） 错误：任务“：app:compiledBugJavaWithJavaC”的执行失败。 编译失败；有关详细信息，请参阅编译器错误输出

如何修复这两个错误。顺便说一下，我是java编码的初学者。 如果你发现我哪里出了问题，请帮我。。我还没有发现任何教程使用Android Studio中提供的默认“LoginActivity”布局。我想连接loginactivity.java和PHP MySql连接

package com.example.chethan.myapplication;
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.annotation.TargetApi;
import android.app.LoaderManager.LoaderCallbacks;
import android.content.CursorLoader;
import android.content.Intent;
import android.content.Loader;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.support.annotation.NonNull;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.inputmethod.EditorInfo;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.List;

import static android.Manifest.permission.READ_CONTACTS;
import static java.net.URLEncoder.encode;
   /**
    * A login screen that offers login via email/password.
    */

 public class LoginPage extends AppCompatActivity implements LoaderCallbacks<Cursor> {

/**
 * Id to identity READ_CONTACTS permission request.
 */
private static final int REQUEST_READ_CONTACTS = 0;

/**
 * A dummy authentication store containing known user names and passwords.
 * TODO: remove after connecting to a real authentication system.
 */
private static final String[] DUMMY_CREDENTIALS = new String[]{
        "foo@example.com:hello", "bar@example.com:world"
};
/**
 * Keep track of the login task to ensure we can cancel it if requested.
 */
private UserLoginTask mAuthTask = null;

// UI references.
private AutoCompleteTextView mEmailView;
private EditText mPasswordView;
private View mProgressView;
private View mLoginFormView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login_page);
    // Set up the login form.
    mEmailView = (AutoCompleteTextView) findViewById(R.id.email);
    populateAutoComplete();

    mPasswordView = (EditText) findViewById(R.id.password);
    mPasswordView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
        @Override
        public boolean onEditorAction(TextView textView, int id, KeyEvent keyEvent) {
            if (id == R.id.login || id == EditorInfo.IME_NULL) {
                attemptLogin();
                return true;
            }
            return false;
        }
    });

    Button mEmailSignInButton = (Button) findViewById(R.id.email_sign_in_button);
    mEmailSignInButton.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View view) {
            attemptLogin();


        }
    });

    mLoginFormView = findViewById(R.id.login_form);
    mProgressView = findViewById(R.id.login_progress);
}

private void populateAutoComplete() {
    if (!mayRequestContacts()) {
        return;
    }

    getLoaderManager().initLoader(0, null, this);
}

private boolean mayRequestContacts() {
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
        return true;
    }
    if (checkSelfPermission(READ_CONTACTS) == PackageManager.PERMISSION_GRANTED) {
        return true;
    }
    if (shouldShowRequestPermissionRationale(READ_CONTACTS)) {
        Snackbar.make(mEmailView, R.string.permission_rationale, Snackbar.LENGTH_INDEFINITE)
                .setAction(android.R.string.ok, new View.OnClickListener() {
                    @Override
                    @TargetApi(Build.VERSION_CODES.M)
                    public void onClick(View v) {
                        requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS);
                    }
                });
    } else {
        requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS);
    }
    return false;
}

/**
 * Callback received when a permissions request has been completed.
 */
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
                                       @NonNull int[] grantResults) {
    if (requestCode == REQUEST_READ_CONTACTS) {
        if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            populateAutoComplete();
        }
    }
}


/**
 * Attempts to sign in or register the account specified by the login form.
 * If there are form errors (invalid email, missing fields, etc.), the
 * errors are presented and no actual login attempt is made.
 */
private void attemptLogin() {
    if (mAuthTask != null) {
        return;
    }

    // Reset errors.
    mEmailView.setError(null);
    mPasswordView.setError(null);

    // Store values at the time of the login attempt.
    String email = mEmailView.getText().toString();
    String password = mPasswordView.getText().toString();

    boolean cancel = false;
    View focusView = null;

    // Check for a valid password, if the user entered one.
    if (!TextUtils.isEmpty(password) && !isPasswordValid(password)) {
        mPasswordView.setError(getString(R.string.error_invalid_password));
        focusView = mPasswordView;
        cancel = true;
    }

    // Check for a valid email address.
    if (TextUtils.isEmpty(email)) {
        mEmailView.setError(getString(R.string.error_field_required));
        focusView = mEmailView;
        cancel = true;
    } else if (!isEmailValid(email)) {
        mEmailView.setError(getString(R.string.error_invalid_email));
        focusView = mEmailView;
        cancel = true;
    }

    if (cancel) {
        // There was an error; don't attempt login and focus the first
        // form field with an error.
        focusView.requestFocus();
    } else {
        // Show a progress spinner, and kick off a background task to
        // perform the user login attempt.
        showProgress(true);
        mAuthTask = new UserLoginTask(email, password);
       // mAuthTask.execute((Void) null);
        mAuthTask.execute();
    }
}

private boolean isEmailValid(String email) {
    //TODO: Replace this with your own logic
    return email.contains("@");
}

private boolean isPasswordValid(String password) {
    //TODO: Replace this with your own logic
    return password.length() > 4;
}

/**
 * Shows the progress UI and hides the login form.
 */
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR2)
private void showProgress(final boolean show) {
    // On Honeycomb MR2 we have the ViewPropertyAnimator APIs, which allow
    // for very easy animations. If available, use these APIs to fade-in
    // the progress spinner.
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
        int shortAnimTime = getResources().getInteger(android.R.integer.config_shortAnimTime);

        mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE);
        mLoginFormView.animate().setDuration(shortAnimTime).alpha(
                show ? 0 : 1).setListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE);
            }
        });

        mProgressView.setVisibility(show ? View.VISIBLE : View.GONE);
        mProgressView.animate().setDuration(shortAnimTime).alpha(
                show ? 1 : 0).setListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                mProgressView.setVisibility(show ? View.VISIBLE : View.GONE);
            }
        });
    } else {
        // The ViewPropertyAnimator APIs are not available, so simply show
        // and hide the relevant UI components.
        mProgressView.setVisibility(show ? View.VISIBLE : View.GONE);
        mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE);
    }
}

@Override
public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
    return new CursorLoader(this,
            // Retrieve data rows for the device user's 'profile' contact.
            Uri.withAppendedPath(ContactsContract.Profile.CONTENT_URI,
                    ContactsContract.Contacts.Data.CONTENT_DIRECTORY), ProfileQuery.PROJECTION,

            // Select only email addresses.
            ContactsContract.Contacts.Data.MIMETYPE +
                    " = ?", new String[]{ContactsContract.CommonDataKinds.Email
            .CONTENT_ITEM_TYPE},

            // Show primary email addresses first. Note that there won't be
            // a primary email address if the user hasn't specified one.
            ContactsContract.Contacts.Data.IS_PRIMARY + " DESC");
}

@Override
public void onLoadFinished(Loader<Cursor> cursorLoader, Cursor cursor) {
    List<String> emails = new ArrayList<>();
    cursor.moveToFirst();
    while (!cursor.isAfterLast()) {
        emails.add(cursor.getString(ProfileQuery.ADDRESS));
        cursor.moveToNext();
    }

    addEmailsToAutoComplete(emails);
}

@Override
public void onLoaderReset(Loader<Cursor> cursorLoader) {

}

private void addEmailsToAutoComplete(List<String> emailAddressCollection) {
    //Create adapter to tell the AutoCompleteTextView what to show in its dropdown list.
    ArrayAdapter<String> adapter =
            new ArrayAdapter<>(LoginPage.this,
                    android.R.layout.simple_dropdown_item_1line, emailAddressCollection);

    mEmailView.setAdapter(adapter);
}


private interface ProfileQuery {
    String[] PROJECTION = {
            ContactsContract.CommonDataKinds.Email.ADDRESS,
            ContactsContract.CommonDataKinds.Email.IS_PRIMARY,
    };

    int ADDRESS = 0;
    int IS_PRIMARY = 1;
}

/**
 * Represents an asynchronous login/registration task used to authenticate
 * the user.
 */
public class UserLoginTask extends AsyncTask<String, String, String> {

    private final String mEmail;
    private final String mPassword;

    UserLoginTask(String email, String password) {
        mEmail = email;
        mPassword = password;
    }

    @Override
    protected String doInBackground(String... params) {
        // TODO: attempt authentication against a network service.

        try {
            // Simulate network access.
            //Thread.sleep(2000);
            String username = (String)params[0];
            String password = (String)params[1];

            String link="http://localhost/login.php";
            String data  = encode("username", "UTF-8") + "=" + encode(username, "UTF-8");
            data += "&" + encode("password", "UTF-8") + "=" + encode(password, "UTF-8");

            URL url = new URL(link);
            URLConnection conn = url.openConnection();

            conn.setDoOutput(true);
            OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());

            wr.write( data );
            wr.flush();

            BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));

            StringBuilder sb = new StringBuilder();
            String line = null;

            // Read Server Response
            while((line = reader.readLine()) != null)
            {
                sb.append(line);
                break;
            }
            return sb.toString();
        }
        catch (Exception e) {
            //return false;
            return new String("Exception: " + e.getMessage());
        }
/*
        for (String credential : DUMMY_CREDENTIALS) {
            String[] pieces = credential.split(":");
            if (pieces[0].equals(mEmail)) {
                // Account exists, return true if the password matches.
                return pieces[1].equals(mPassword);
            }
        }
 */
 /*          TODO: register the new account here. */
 /*            return true;  */
    }

    @Override
    protected void onPostExecute(final Boolean success) {
 //            super.onPostExecute(success);
        mAuthTask = null;
        showProgress(false);

        if (success) {

            finish();
            Toast.makeText(getApplicationContext(),"login success",Toast.LENGTH_SHORT).show();
            Intent myIntent = new Intent(LoginPage.this,Authorities.class);
            LoginPage.this.startActivity(myIntent);
        } else {
            mPasswordView.setError(getString(R.string.error_incorrect_password));
            mPasswordView.requestFocus();
        }
    }

    @Override
    protected void onCancelled() {
        mAuthTask = null;
        showProgress(false);
    }
}
}

package com.example.chethan.myapplication；
导入android.animation.Animator；
导入android.animation.AnimatorListenerAdapter；
导入android.annotation.TargetApi；
导入android.app.LoaderManager.LoaderCallbacks；
导入android.content.CursorLoader；
导入android.content.Intent；
导入android.content.Loader；
导入android.content.pm.PackageManager；
导入android.database.Cursor；
导入android.net.Uri；
导入android.os.AsyncTask；
导入android.os.Build；
导入android.os.Bundle；
导入android.provider.contacts合同；
导入android.support.annotation.NonNull；
导入android.support.design.widget.Snackbar；
导入android.support.v7.app.AppActivity；
导入android.text.TextUtils；
导入android.view.KeyEvent；
导入android.view.view；
导入android.view.view.OnClickListener；
导入android.view.inputmethod.EditorInfo；
导入android.widget.ArrayAdapter；
导入android.widget.AutoCompleteTextView；
导入android.widget.Button；
导入android.widget.EditText；
导入android.widget.TextView；
导入android.widget.Toast；
导入java.io.BufferedReader；
导入java.io.InputStreamReader；
导入java.io.OutputStreamWriter；
导入java.net.URL；
导入java.net.URLConnection；
导入java.net.urlcoder；
导入java.util.ArrayList；
导入java.util.List；
导入静态android.Manifest.permission.READ_联系人；
导入静态java.net.URLEncoder.encode；
/**
*提供通过电子邮件/密码登录的登录屏幕。
*/
公共类LoginPage扩展AppCompatActivity实现LoaderCallbacks{
/**
*身份识别读取\联系人权限请求的Id。
*/
私有静态最终int请求\u读取\u联系人=0；
/**
*包含已知用户名和密码的虚拟身份验证存储。
*TODO:连接到真实身份验证系统后删除。
*/
私有静态最终字符串[]伪\u凭据=新字符串[]{
"foo@example.com：你好“bar@example.com：世界“
};
/**
*跟踪登录任务，确保我们可以根据请求取消它。
*/
private UserLoginTask mAuthTask=null；
//用户界面引用。
私有AutoCompleteTextView mEmailView；
私有编辑文本mPasswordView；
私有视图mProgressView；
私有视图mloginfo视图；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity\u login\u页面）；
//设置登录表单。
mEmailView=（AutoCompleteTextView）findviewbyd（R.id.email）；
populateAutoComplete（）；
mPasswordView=（EditText）findViewById（R.id.password）；
mPasswordView.setOnEditorActionListener（新的TextView.OnEditorActionListener（）{
@凌驾
公共布尔onEditorAction（TextView TextView、int id、KeyEvent KeyEvent）{
if（id==R.id.login | | id==EditorInfo.IME_NULL）{
尝试登录（）；
返回true；
}
返回false；
}
});
按钮mEmailSignInButton=（按钮）findViewById（R.id.email\u sign\u in\u按钮）；
setOnClickListener（新的OnClickListener（））{
@凌驾
公共void onClick（视图）{
尝试登录（）；
}
});
mLoginFormView=findviewbyd（R.id.login\u表单）；
mProgressView=findviewbyd（R.id.login\u progress）；
}
私有void populateAutoComplete（）{
如果（！mayRequestContacts（））{
返回；
}
getLoaderManager（）.initLoader（0，null，this）；
}
私有布尔mayRequestContacts（）{
if（Build.VERSION.SDK_INT protected void onPostExecute(final String success) {
     //            super.onPostExecute(success);
    mAuthTask = null;
    showProgress(false);

    if (success.equals("true")) {

        finish();
        Toast.makeText(getApplicationContext(),"login success",Toast.LENGTH_SHORT).show();
        Intent myIntent = new Intent(LoginPage.this,Authorities.class);
        LoginPage.this.startActivity(myIntent);
    } else {
        mPasswordView.setError(getString(R.string.error_incorrect_password));
        mPasswordView.requestFocus();
    }
}