android - SharedPreference 无法跨 Activity 保存数据

Question

我正在开发启动画面，它将根据 SharedPreference 存储的值确定用户之前是否注册过。

请允许我再问一次这个问题，因为我已经阅读了很多帮助/教程和示例，但一点帮助也没有。我已经被困在这里 2 天了......非常感谢任何帮助。

涉及 2 个 Activity 。该应用程序以 SplashScreen Activity 开始，然后如果 sharepreference 文件返回非空(意味着用户之前注册过)，它将启动 mainactivity。否则如果 sharepreference 文件返回 null(意味着第一次用户，它将用户带到注册 Activity )...

问题:每当应用程序重新启动时(即使用户已注册)，它总是会转到注册页面!请帮忙 !!

SPLASHSCREEN Activity 的代码

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

    Thread timerThread = new Thread(){
        public void run(){
            try{
                sleep(3000);
            }catch(InterruptedException e){
                e.printStackTrace();
            }finally{

            }
        }
    };
    timerThread.start();

}

protected void onStart() {
    super.onStart();
    openNextActivity();
}

public void openNextActivity(){

    SharedPreferences sp = getSharedPreferences("pref", 0);
    if (sp.contains("Name")) {
        Intent intent = new Intent(SplashScreen.this, MainActivity.class);
        startActivity(intent);
    } else {
        Intent intent = new Intent(SplashScreen.this, Registration.class);
        startActivity(intent);
    }

}

@Override
protected void onPause() {
    super.onPause();
    finish();
}

下面是注册 Activity 的代码...

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

    etName = (EditText) findViewById(R.id.etName);
    etEmail = (EditText) findViewById(R.id.etEmail);
    etMobilePhone = (EditText) findViewById(R.id.etMobilePhone);
    tel = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE); // imei

    btnSubmit = (Button) findViewById(R.id.btnSubmit);
    btnSubmit.setOnClickListener(this);


}


public void onClick(View v) {
    switch (v.getId()) {
        case R.id.btnSubmit:
            writePref();
            break;
    }
    finish();
}


private void writePref() {

    String userName  = etName.getText().toString();             //prepare variables values for write
    String userPhone  = etMobilePhone.getText().toString();     //prepare variables values for write
    String userEmail  = etEmail.getText().toString();           //prepare variables values for write
    String userImei = tel.getDeviceId().toString();             //prepare variables values for write

    SharedPreferences sp = getSharedPreferences("pref", 0);     //sharepreference
    SharedPreferences.Editor editor = sp.edit();                //sharepreference
    editor.putString(Name, userName);                           //write sharepreferences
    editor.putString(Phone, userPhone);                         //write sharepreferences
    editor.putString(Email, userEmail);                         //write sharepreferences
    editor.putString(Imei, userImei);                           //write sharepreferences
    editor.commit();                                            //sharepreference

    Toast toast = Toast.makeText(getApplicationContext(), "updated sharepreferences", Toast.LENGTH_SHORT);
    toast.setGravity(Gravity.BOTTOM | Gravity.CENTER_HORIZONTAL,0,50);
    toast.show();

}

请指导我正确的方向。感谢您阅读和回复。

Answer 1

将您的 openNextActivity() 方法更改为:

public void openNextActivity(){

    SharedPreferences sp = getSharedPreferences("pref", 0);
    String defaultValue = "na";
    String storedValue = sp.getString("Name", defaultValue);

    if (!storedValue.equalsIgnoreCase("na")) {
        Intent intent = new Intent(SplashScreen.this, MainActivity.class);
        startActivity(intent);
    } else { //if you get default value i.e. "na"
        Intent intent = new Intent(SplashScreen.this, Registration.class);
        startActivity(intent);
    }

}

不是检查键是否存在，而是检查它的值。如果找不到键，则返回默认值并检查返回值。

更新(来自下面 Jelle 的评论): 同时更改您的 RegistrationActivity。将 editor.putString(Name, userName); 更改为 editor.putString("Name", userName);