将用户从Java注销

我正在创建一个带有登录/注册系统的社交应用程序，用户注销时遇到问题

当我单击注销按钮时，我想取消用户名设置并清除用户的整个会话，以便他们返回

LoginActivity

类。现在，当我转到profile活动并单击logout时，我会直接返回Home活动，该活动仅适用于登录的用户。从昨天开始我就一直在努力，但还是一无所获。有人能帮我吗

登录活动：

//SharedPreferences preferences;

private ProgressDialog loadingBar;

private Button LoginButton;
private EditText LoginUsername, LoginPassword;
private TextView NeedNewAccountLink;
private static final String PREF_LOGIN = "LOGIN_PREF";

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

    //SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(PREF_LOGIN, MODE_PRIVATE);
    SharedPreferences sharedPreferences = getSharedPreferences(PREF_LOGIN, MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();

}

LoginButton = (Button) findViewById(R.id.login_button);
    LoginUsername = (EditText) findViewById(R.id.login_username);
    LoginPassword = (EditText) findViewById(R.id.login_password);
    NeedNewAccountLink = (TextView) findViewById(R.id.need_new_account_link);
    loadingBar = new ProgressDialog(this);

    editor.putString("username", String.valueOf(LoginUsername));
    editor.putString("pw", String.valueOf(LoginPassword));
    editor.apply();

    if (LoginUsername != null) {

        editor.remove("username");
        editor.remove(String.valueOf(sharedPreferences));
        editor.remove("pw");
        editor.clear();
        editor.apply();

        SendUserToHomeActivity();
    }

private void SendUserToHomeActivity() {

    Intent mainIntent = new Intent(LoginActivity.this, HomeActivity.class);
    mainIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
    startActivity(mainIntent);
    finish();
}

public void OnLogin(View view) {

    String username = LoginUsername.getText().toString();
    String pw = LoginPassword.getText().toString();

    String type = "login";

    BackgroundWorker backgroundWorker = new BackgroundWorker(this);
    backgroundWorker.execute(type, username, pw);

}

    LogoutButton.setOnClickListener(view -> {

        PreferenceManager.getDefaultSharedPreferences(getBaseContext()).edit().clear().apply();

        sharedPreferences.edit().remove("username").apply();
        sharedPreferences.edit().remove("pw").apply();

        editor.remove("username");
        editor.remove("pw");
        editor.clear();
        editor.apply();

        finish();

        Intent intent = new Intent(ProfileActivity.this, LoginActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
        startActivity(intent);

    });

配置文件活动：

//SharedPreferences preferences;

private ProgressDialog loadingBar;

private Button LoginButton;
private EditText LoginUsername, LoginPassword;
private TextView NeedNewAccountLink;
private static final String PREF_LOGIN = "LOGIN_PREF";

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

    //SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(PREF_LOGIN, MODE_PRIVATE);
    SharedPreferences sharedPreferences = getSharedPreferences(PREF_LOGIN, MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();

}

LoginButton = (Button) findViewById(R.id.login_button);
    LoginUsername = (EditText) findViewById(R.id.login_username);
    LoginPassword = (EditText) findViewById(R.id.login_password);
    NeedNewAccountLink = (TextView) findViewById(R.id.need_new_account_link);
    loadingBar = new ProgressDialog(this);

    editor.putString("username", String.valueOf(LoginUsername));
    editor.putString("pw", String.valueOf(LoginPassword));
    editor.apply();

    if (LoginUsername != null) {

        editor.remove("username");
        editor.remove(String.valueOf(sharedPreferences));
        editor.remove("pw");
        editor.clear();
        editor.apply();

        SendUserToHomeActivity();
    }

private void SendUserToHomeActivity() {

    Intent mainIntent = new Intent(LoginActivity.this, HomeActivity.class);
    mainIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
    startActivity(mainIntent);
    finish();
}

public void OnLogin(View view) {

    String username = LoginUsername.getText().toString();
    String pw = LoginPassword.getText().toString();

    String type = "login";

    BackgroundWorker backgroundWorker = new BackgroundWorker(this);
    backgroundWorker.execute(type, username, pw);

}

    LogoutButton.setOnClickListener(view -> {

        PreferenceManager.getDefaultSharedPreferences(getBaseContext()).edit().clear().apply();

        sharedPreferences.edit().remove("username").apply();
        sharedPreferences.edit().remove("pw").apply();

        editor.remove("username");
        editor.remove("pw");
        editor.clear();
        editor.apply();

        finish();

        Intent intent = new Intent(ProfileActivity.this, LoginActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
        startActivity(intent);

    });

---

我相信从你需要的编辑文本中获取文本

LoginUsername.getText（）.toString（）

并根据If条件检查EditText“LoginUsername”，除非 它指向错误的ID

尝试在下面的代码块中进行适当的更改

    LoginUsername = (EditText) findViewById(R.id.login_username);
    LoginPassword = (EditText) findViewById(R.id.login_password);
    NeedNewAccountLink = (TextView) findViewById(R.id.need_new_account_link);
    loadingBar = new ProgressDialog(this);

    editor.putString("username", String.valueOf(LoginUsername));
    editor.putString("pw", String.valueOf(LoginPassword));
    editor.apply();

    if (LoginUsername != null) {

        editor.remove("username");
        editor.remove(String.valueOf(sharedPreferences));
        editor.remove("pw");
        editor.clear();
        editor.apply();

        SendUserToHomeActivity();
    }

---

删除

意图。标志\u活动\u清除\u顶部

标志将解决您的问题。请参阅此项。

使用“finish（）”方法，您将从堆栈中清除当前活动（ProfileActivity），并从不再存在的“ProfileActivity”中调用意图。只需将“finish（）”保持在您的意图调用下面。除了前面的答案之外，不要使用SharedReferences.apply，请使用commit（）。Apply是异步的，在启动登录活动时可能不会写入磁盘。在这种情况下，您可以直接转到主页。@Gabeschen我尝试了这个

PreferenceManager.GetDefaultSharedReferences（getBaseContext（））.edit（）.clear（）.commit（）但它仍然不起作用我不明白为什么要同时使用remove和clear。要删除特定密钥时，请使用“删除”。在您的情况下，只需使用editor.clear（）.apply（）。并确保编辑器对象在两个活动中引用相同的共享pref