Question

我有这个应用程序，我成功从登录活动发送意图并接收用户活动的意图（请参阅附件），但当我从其他页面导航然后返回到我的UserAcitivy ie;主页，联系我们结果＆＃34;空值＆＃34;，我想将数据保存在用户活动中，即使我从其他页面导航。请帮忙。谢谢！

Successful store

Null values

这是我的代码..

公共类LoginActivityEN扩展了AppCompatActivity {

class Abc
  arr_accessor :my_arrayobject

  def initialize
      self.my_arrayojbect = []
  end
  ....
  def update
     self.my_arrayobject << parameter
  end
end

p1 = Abc.new
puts p1.my_arrayobject

UserActivity.java

公共类UserActivity扩展了AppCompatActivity {

private static final String TAG = "LoginActivity";
private static final String URL_FOR_LOGIN = "http://192.168.13.40/android_login_example/login.php";
ProgressDialog progressDialog;
private EditText loginInputUsername, loginInputPassword;
Button btnlogin;
Button btnLinkSignup;


// Session Manager Class
SessionManager session;

//Storing Sessions
SharedPreferences sharedPreferences;


@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        overridePendingTransition(R.anim.fadein, R.anim.fadeout);
        setContentView(R.layout.activity_login_en);




    // Session Manager
    session = new SessionManager(getApplicationContext());
    sharedPreferences = getSharedPreferences("my_prefs", MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putString("user_id", "password");


    //Bottom Navigation
    BottomNavigationView bottomNavigationView = (BottomNavigationView) findViewById(R.id.bottomNavView_Bar);
        BottomNavigationViewHelper.disableShiftMode(bottomNavigationView);
        Menu menu = bottomNavigationView.getMenu();
        MenuItem menuItem = menu.getItem(1);
        menuItem.setChecked(true);

        bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                switch (item.getItemId()){

                    case R.id.navigation_home:
                        Intent intent1 = new Intent(LoginActivityEN.this, Home.class);
                        startActivity(intent1);
                        break;

                    case R.id.navigation_card:



                        break;

                    case R.id.navigation_price:
                        Intent intent3 = new Intent(LoginActivityEN.this, PriceActivity.class);
                        startActivity(intent3);
                        break;
                    case R.id.navigation_more:
                        Intent intent4 = new Intent(LoginActivityEN.this, More.class);
                        startActivity(intent4);
                }
                return false;
            }
        });


        //Login Activity
        loginInputUsername = (EditText) findViewById(R.id.login_input_username);
        loginInputPassword = (EditText) findViewById(R.id.login_input_password);
        btnlogin = (Button) findViewById(R.id.btn_login);
        btnLinkSignup = (Button) findViewById(R.id.registerbutton);
        // Progress dialog
        progressDialog = new ProgressDialog(this);
        progressDialog.setCancelable(false);

        btnlogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                loginUser(loginInputUsername.getText().toString(),
                        loginInputPassword.getText().toString());

            }
        });
        //Register
        btnLinkSignup.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent i = new Intent(getApplicationContext(), RegisterEN.class);
                startActivity(i);
            }
        });
    }

private void loginUser( final String username, final String password) {


    // Tag used to cancel the request
    String cancel_req_tag = "login";
    progressDialog.setMessage("Logging you in...");
    showDialog();
    StringRequest strReq = new StringRequest(Request.Method.POST,
            URL_FOR_LOGIN, new Response.Listener<String>() {

        @Override
        public void onResponse(String response) {
            Log.d(TAG, "Register Response: " + response.toString());
            hideDialog();
            try {
                JSONObject jObj = new JSONObject(response);
                boolean error = jObj.getBoolean("error");

                if (!error) {
                    String user = jObj.getJSONObject("user").getString("customers_firstname");
                    String user1 = jObj.getJSONObject("user").getString("customers_lastname");
                    String user2 = jObj.getJSONObject("user").getString("reward_points");
                    String user3 = jObj.getJSONObject("user").getString("NoShares");
                    String user4 = jObj.getJSONObject("user").getString("CardType_ID");
                    String user5 = jObj.getJSONObject("user").getString("Card_No");
                    // Launch User activity
                    Intent intent = new Intent(LoginActivityEN.this, UserActivity.class);
                    intent.putExtra("customers_firstname", user);
                    intent.putExtra("customers_lastname", user1);
                    intent.putExtra("reward_points", user2);
                    intent.putExtra("NoShares", user3);
                    intent.putExtra("CardType_ID", user4);
                    intent.putExtra("Card_No", user5);
                    startActivity(intent);
                    finish();

                    if(username.trim().length() > 0 && password.trim().length() > 0){
                        session.createLoginSession("username", "password");
                        Toast.makeText(getApplicationContext(), "Session Active", Toast.LENGTH_SHORT).show();

                    }

                } else {

                    String errorMsg = jObj.getString("error_msg");
                    Toast.makeText(getApplicationContext(),
                            errorMsg, Toast.LENGTH_SHORT).show();
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

        }
    }, new Response.ErrorListener() {

        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e(TAG, "Login Error: " + error.getMessage());
            Toast.makeText(getApplicationContext(),
                    error.getMessage(), Toast.LENGTH_SHORT).show();
            hideDialog();
        }
    }) {

        @Override
        protected Map<String, String> getParams() {
            // Posting params to login url
            Map<String, String> params = new HashMap<String, String>();
            params.put("username", username);
            params.put("customers_password", password);
            return params;
        }

    };
    // Adding request to request queue
    AppSingleton.getInstance(getApplicationContext()).addToRequestQueue(strReq,cancel_req_tag);
}

private void showDialog() {
    if (!progressDialog.isShowing())
        progressDialog.show();
}
private void hideDialog() {
    if (progressDialog.isShowing())
        progressDialog.dismiss();
}

Answer 1

您可以使用许多方法。

持久存储（长时间，即使应用关闭后）：一个。使用SharedPreferences，b。使用Sqlite
其他方式是.to扩展Application类并将其存储在变量中，直到应用程序关闭为止。（短期，应用程序会话和关闭应用程序）

您的方法取决于您的数据生命周期

如何将数据保存在数据库中的活动中

1 个答案: