Question

我将两部分数据保存为用户密码和用户名，以便在以后的数据和随机字母组合中使用，然后检查应用程序何时再次执行以避免再次登录屏幕。

我昨天有这个工作，出于某种原因，我希望在添加功能时我放错了代码而现在无法让它再次运行，我已经整天尝试修复它，但我不能。

EDIT1：出于某种原因，它会转到“CheckPrefs”方法的else语句，，我无法理解。

EDIT2：它可以保存首选项并转到意图，但是它无法读取它。

代码：

public static final String PREFS_NAME = "MyPregs";
    public static final String PREFS_CHECK = "CheckSignedIn";
    public static final String UID ="";
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        CheckPrefs();

        // Login button clicked
        ok = (Button) findViewById(R.id.btn_login);
        ok.setOnClickListener(this);

        result = (TextView) findViewById(R.id.lbl_result);

    } 
    private void CheckPrefs() {
        // TODO Auto-generated method stub
        //checks to see if the user has signed in before if they have it gets there data from SharedPreferences and checks against our database via HttpPost.
        SharedPreferences settings = getSharedPreferences(PREFS_CHECK, 0);
        String SCheck1 = settings.getString("key4", null);
        if (SCheck1 != null  && equals(UID)) {
            Intent c = new Intent(this, CheckUserInfo.class);
            startActivity(c);   

        } else {

        }



    }
    //create bracket.

    public void postLoginData() {

        // Create a new HttpClient and Post Header
        HttpClient httpclient = new DefaultHttpClient();

        /* login.php returns true if username and password is equal to saranga */
        HttpPost httppost = new HttpPost("http://gta5news.com/login.php");

        try {
            // Add user name and password
            uname = (EditText) findViewById(R.id.txt_username);
            String username = uname.getText().toString();

            pword = (EditText) findViewById(R.id.txt_password);
            String password = pword.getText().toString();

            SharedPreferences signedin = getSharedPreferences(PREFS_CHECK, 0);
            SharedPreferences.Editor editor1 = signedin.edit();
            editor1.putString("key4", UID);
            editor1.commit();


            SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
            SharedPreferences.Editor editor = settings.edit();
            editor.putString("key1", username);
            editor.putString("key2", password);
            editor.commit();

            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
            nameValuePairs.add(new BasicNameValuePair("username", username));
            nameValuePairs.add(new BasicNameValuePair("password", password));
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

            // Execute HTTP Post Request
            Log.w("HttpPost", "Execute HTTP Post Request");
            HttpResponse response = httpclient.execute(httppost);

            String str = inputStreamToString(response.getEntity().getContent())
                    .toString();
            Log.w("HttpPost", str);

            if (str.toString().equalsIgnoreCase("true")) {
                Log.w("HttpPost", "TRUE");
                result.setText("Login successful");
                try {Thread.sleep(250);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                Intent login = new Intent(LogIn.this, ChatService.class);
                startActivity(login);

            } else {
                Log.w("HttpPost", "FALSE");
                result.setText(str);
            }

        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private StringBuilder inputStreamToString(InputStream is) {
        String line = "";
        StringBuilder total = new StringBuilder();
        // Wrap a BufferedReader around the InputStream
        BufferedReader rd = new BufferedReader(new InputStreamReader(is));
        // Read response until the end
        try {
            while ((line = rd.readLine()) != null) {
                total.append(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        // Return full string
        return total;
    }

    public void onClick(View view) {
        if (view == ok) {

            postLoginData();
            InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
            imm.hideSoftInputFromWindow(pword.getWindowToken(), 0);
        }
        // Click end
    }
    // if statement
}

// class ends here

Answer 1

需要查看保存偏好的位置，以便我们可以将其与您的偏好设置相匹配......但是，这是一个错字吗？

public static final String PREFS_NAME = "MyPregs";

应该是“MyPrefs”而不是“MyPregs”吗？

Answer 2

你有

if (SCheck1 != null  && equals(UID))

但是你可能想说

if (SCheck1 != null  && !SCheck.equals(UID))

Answer 3

你也可以使用'反向比较'模式：

if (UID.equals(SCheck1)) {

} else {

}

这样，您不必费心检查SCheck1 == null。 UID.equals（null）将返回false而不是null.equals（UID）抛出NullPointerException。

SharedPreferences不读取数据

3 个答案: