.setText 使用 SharedPreferences 不起作用

Question

我带着另一个问题来到这里，这次是关于 Android 应用程序。

我制作了一个带有 Login 活动（没有 NavigationView）的应用程序，它在登录后将我们移动到 NavigationView 所在的 Home 活动。用户数据保存在 SharedPreferences 中，我使用的是 Constants 类。 我的问题是我无法在 Home 活动上使用 SharedPreferences setText，但它在 Login 活动上工作（ EditText 中插入电子邮件地址）。 这是我的代码：

Login.java

package com.example.appname;

import android.app.Fragment;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.Color;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.AppCompatButton;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.example.appname.models.ServerRequest;
import com.example.appname.models.ServerResponse;
import com.example.appname.models.User;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class Login extends AppCompatActivity {


private CoordinatorLayout coordinatorLayout;

private AppCompatButton btn_login;
private EditText et_email,et_password;
private TextView tv_register;
private ProgressBar progress;
private SharedPreferences pref;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    coordinatorLayout = (CoordinatorLayout) findViewById(R.id.coordinatorLayout);

    pref = getPreferences(0);


    btn_login = (AppCompatButton)findViewById(R.id.btn_login);
    tv_register = (TextView)findViewById(R.id.tv_register);
    et_email = (EditText)findViewById(R.id.et_email);
    et_email.setText(pref.getString(Constants.EMAIL, ""));
    et_password = (EditText)findViewById(R.id.et_password);

    progress = (ProgressBar)findViewById(R.id.progress);

    btn_login.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View view) {
            String email = et_email.getText().toString();
            String password = et_password.getText().toString();

            if(!email.isEmpty() && !password.isEmpty()) {

                progress.setVisibility(View.VISIBLE);
                loginProcess(email,password);

            } else {

                Snackbar snackbar = Snackbar
                        .make(coordinatorLayout, R.string.empty_fields, Snackbar.LENGTH_LONG);

                View sbView = snackbar.getView();
                TextView textView = (TextView) sbView.findViewById(android.support.design.R.id.snackbar_text);
                textView.setTextColor(Color.GREEN);
                snackbar.show();
            }
        }

    });

    tv_register.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            Intent intent = new Intent(getApplicationContext(), Register.class);

            startActivity(intent);
            finish();
        }
    });


}






private void loginProcess(String email,String password){

    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(Constants.BASE_URL)
            .addConverterFactory(GsonConverterFactory.create())
            .build();

    RequestInterface requestInterface = retrofit.create(RequestInterface.class);

    User user = new User();
    user.setEmail(email);
    user.setPassword(password);
    ServerRequest request = new ServerRequest();
    request.setOperation(Constants.LOGIN_OPERATION);
    request.setUser(user);
    Call<ServerResponse> response = requestInterface.operation(request);

    response.enqueue(new Callback<ServerResponse>() {
        @Override
        public void onResponse(Call<ServerResponse> call, retrofit2.Response<ServerResponse> response) {

            ServerResponse resp = response.body();
            Snackbar.make(coordinatorLayout, resp.getMessage(), Snackbar.LENGTH_LONG).show();

            if(resp.getResult().equals(Constants.SUCCESS)){
                SharedPreferences.Editor editor = pref.edit();
                editor.putBoolean(Constants.IS_LOGGED_IN,true);
                editor.putString(Constants.EMAIL,resp.getUser().getEmail());
                editor.putString(Constants.NAME,resp.getUser().getName());
                editor.putString(Constants.UNIQUE_ID,resp.getUser().getUnique_id());
                editor.putString(Constants.POINTS,resp.getUser().getPoints());
                editor.apply();
                goToHome();

            }
            progress.setVisibility(View.INVISIBLE);
        }

        @Override
        public void onFailure(Call<ServerResponse> call, Throwable t) {

            progress.setVisibility(View.INVISIBLE);
            Log.d(Constants.TAG,"failed");
            Snackbar.make(coordinatorLayout, t.getLocalizedMessage(), Snackbar.LENGTH_LONG).show();

        }
    });
}



private void goToHome(){

    Intent intent = new Intent(getApplicationContext(), Home.class);

    startActivity(intent);
}
}

Home.java

package com.examle.appname;

import android.app.ActivityOptions;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.design.internal.NavigationMenuPresenter;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.NavigationView;
import android.support.design.widget.Snackbar;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.View;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;

public class Home extends AppCompatActivity implements 
NavigationView.OnNavigationItemSelectedListener {
private DrawerLayout drawerLayout;
private Toolbar toolbar;
private SharedPreferences pref;
private TextView tvname, tvpoints;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);

    pref = getPreferences(0);

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    tvname = (TextView)findViewById(R.id.tv_name);
    tvpoints = (TextView)findViewById(R.id.tv_points);
    tvname.setText(pref.getString(Constants.NAME, ""));
    tvpoints.setText(pref.getString(Constants.POINTS, "") +R.string.act_points);



    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.drawer_open, R.string.drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nvView);
    navigationView.setNavigationItemSelectedListener((NavigationView.OnNavigationItemSelectedListener) this);
    View headerView = navigationView.getHeaderView(0);
    TextView tvemail = (TextView) headerView.findViewById(R.id.tv_email);
    tvemail.setText(pref.getString(Constants.EMAIL, ""));

}

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    int id = item.getItemId();     
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

@SuppressWarnings("StatementWithEmptyBody")


public boolean onNavigationItemSelected(MenuItem item) {

    int id=item.getItemId();
    switch (id){

        case R.id.navigation_home:
            Intent h= new Intent(Home.this,Home.class);
            startActivity(h);
            break;
        case R.id.navigation_showall:
            Intent i= new Intent(Home.this,ShowAllUsers.class);
            startActivity(i);
            break;
        case R.id.navigation_about:
            Intent g= new Intent(Home.this,About.class);
            startActivity(g);
            break;
        case R.id.navigation_settings:
            Intent s= new Intent(Home.this,AccountSettings.class);
            startActivity(s);
        case R.id.navigation_support:
            Intent t= new Intent(Home.this,Support.class);
            startActivity(t);
            break;
    }



    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}
}

Answer 1

使用 getSharedPreferences 而不是这个 getPreferences

Answer 2

试试这个方法

 SharedPreferences sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
    if (sharedpreferences.contains(Constants.NAME)) 
    {
        tvname.setText(sharedpreferences.getString(Constants.NAME, ""));
    }

Answer 3

因为您在不同的活动中使用 SharedPreference 的两个不同实例，所以使用单个实例。更多信息检查 - https://stackoverflow.com/a/11567825/3912847