我已尝试过在共享偏好的其他答案中给出的所有可能的解决方案，但仍然无法解决，因此提出了这个问题。
我一直在使用这些文件
Config.java
public class Config {
//URL to our login.php file
public static final String LOGIN_URL = "http://192.168.211.1/Remedcu/login.php";
public static final String KEY_NAME = "Name";
public static final String KEY_EMAIL = "Email";
public static final String KEY_PASSWORD = "Password";
//If server response is equal to this that means login is successful
public static final String LOGIN_SUCCESS = "success";
//Keys for Sharedpreferences
//This would be the name of our shared preferences
public static final String SHARED_PREF_NAME = "iamhere";
//This would be used to store the email of current logged in user
public static String EMAIL_SHARED_PREF = null;
//We will use this to store the boolean in sharedpreference to track user is loggedin or not
public static String LOGGEDIN_SHARED_PREF = "loggedin";
}
和Login.java
public class Login extends AppCompatActivity {
private static final String TAG = "LoginActivity";
private Vibrator vib;
Animation animShake;
private EditText signupInputName, signupInputPassword;
private TextInputLayout signupInputLayoutName,
signupInputLayoutPassword;
private Button btnSignUp;
ProgressDialog progress;
private static final String LOGIN_URL = "http://192.168.211.1/Remedcu/login.php";
public static final String KEY_NAME = "Username";
public static final String KEY_PASSWORD = "Password";
TextView textView;
private boolean loggedIn = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
signupInputLayoutName = (TextInputLayout) findViewById(R.id.signup_input_layout_name);
signupInputLayoutPassword = (TextInputLayout) findViewById(R.id.signup_input_layout_password);
textView = (TextView) findViewById(R.id.textView2);
textView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(Login.this, Registration.class);
startActivity(intent);
}
});
signupInputName = (EditText) findViewById(R.id.signup_input_name);
signupInputPassword = (EditText) findViewById(R.id.signup_input_password);
btnSignUp = (Button) findViewById(R.id.btn_signup);
animShake = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.shakei);
vib = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
btnSignUp.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
submitForm();
//Intent intent=new Intent(Intent.ACTION_VIEW);
}
});
}
private void submitForm() {
final String Name = signupInputName.getText().toString().trim();
final String Password=signupInputPassword.getText().toString().trim();
StringRequest stringRequest = new StringRequest(Request.Method.POST,LOGIN_URL,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
if(response.equalsIgnoreCase("Invalid credentials")) {
Toast.makeText(Login.this, response, Toast.LENGTH_SHORT).show();
}
//String LOGIN_SUCCESS = "success";
if(response.equalsIgnoreCase("success")){
final String Use ="Welcome "+Name;
Toast.makeText(getApplicationContext(),Use,Toast.LENGTH_SHORT).show();
//Creating a shared preference
SharedPreferences sharedPreferences = Login.this.getSharedPreferences(Config.SHARED_PREF_NAME, Context.MODE_PRIVATE);
//Creating editor to store values to shared preferences
SharedPreferences.Editor editor = sharedPreferences.edit();
//Adding values to editor
editor.putBoolean(Config.LOGGEDIN_SHARED_PREF, true);
editor.putString(Config.EMAIL_SHARED_PREF, Name);
//Saving values to editor
editor.apply();
Toast.makeText(getApplicationContext(), "The data is saved as "+Config.EMAIL_SHARED_PREF,Toast.LENGTH_SHORT).show();
Intent intent = new Intent(Login.this, MapsActivity.class);
startActivity(intent);
}//else{
//If the server response is not success
//Displaying an error message on toast
// Toast.makeText(Login.this, "Invalid credentials", Toast.LENGTH_LONG).show();
//}
// Intent intent = new Intent(Registration.this, MainActivity.class);
// startActivity(intent);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(Login.this,error.toString(),Toast.LENGTH_LONG).show();
}
}){
@Override
protected Map<String,String> getParams(){
Map<String,String> params = new HashMap<String, String>();
params.put(KEY_NAME,Name);
params.put(KEY_PASSWORD,Password);
return params;
}
};
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
if (!checkName()) {
signupInputName.setAnimation(animShake);
signupInputName.startAnimation(animShake);
vib.vibrate(120);
return;
}
if (!checkPassword()) {
signupInputPassword.setAnimation(animShake);
signupInputPassword.startAnimation(animShake);
vib.vibrate(120);
return;
}
signupInputLayoutName.setErrorEnabled(false);
signupInputLayoutPassword.setErrorEnabled(false);
// Toast.makeText(getApplicationContext(),
// "You are logged in !!", Toast.LENGTH_SHORT).show();
}
private boolean checkName() {
if (signupInputName.getText().toString().trim().isEmpty()) {
signupInputLayoutName.setErrorEnabled(true);
signupInputLayoutName.setError(getString(R.string.err_msg_name));
signupInputName.setError(getString(R.string.err_msg_required));
return false;
}
signupInputLayoutName.setErrorEnabled(false);
return true;
}
private boolean checkPassword() {
if (signupInputPassword.getText().toString().trim().isEmpty()) {
signupInputLayoutPassword.setError(getString(R.string.err_msg_password));
requestFocus(signupInputPassword);
return false;
}
signupInputLayoutPassword.setErrorEnabled(false);
return true;
}
private static boolean isValidEmail(String email) {
return !TextUtils.isEmpty(email) &&
android.util.Patterns.EMAIL_ADDRESS.matcher(email).matches();
}
private void requestFocus(View view) {
if (view.requestFocus()) {
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
}
}
@Override
protected void onResume() {
super.onResume();
//In onresume fetching value from sharedpreference
SharedPreferences sharedPreferences = getSharedPreferences(Config.SHARED_PREF_NAME, Context.MODE_PRIVATE);
//Fetching the boolean value form sharedpreferences
loggedIn = sharedPreferences.getBoolean(Config.LOGGEDIN_SHARED_PREF, false);
//If we will get true
if (loggedIn) {
//We will start the Profile Activity
Intent intent = new Intent(Login.this, MapsActivity.class);
startActivity(intent);
}
}}
在我将更改提交给编辑器后的Login.java中，我只是想检查值是否保存。
因此下面的代码就在那里：
Toast.makeText(getApplicationContext(), "The data is saved as "+Config.EMAIL_SHARED_PREF,Toast.LENGTH_SHORT).show();
但每当我运行程序时，登录后，toast总是“数据保存为null”
周围有什么办法吗？
答案 0 :(得分：1)
您需要从sharedPreferences获取电子邮件，即密钥EMAIL_SHARED_PREF的值：
String email = sharedPreferences.getString(Config.EMAIL_SHARED_PREF, "NOT FOUND");
＆＃39;未找到＆＃39;是如果未使用SharedPreferences中的值初始化EMAIL_SHARED_PREF，则将设置为电子邮件的值。接下来，您可以在您的吐司制造商中致电email。
Toast.makeText(getApplicationContext(), "The data is saved as "+ email,Toast.LENGTH_SHORT).show();
答案 1 :(得分：0)
如果您想在密钥Config.EMAIL_SHARED_PREF下查看要保存的内容，请改为运行此代码：
Toast.makeText(getApplicationContext(), "The data is saved as "+sharedPreferences.getString(Config.EMAIL_SHARED_PREF, ""),Toast.LENGTH_SHORT).show();
但是，请注意，您尚未指定Config.EMAIL_SHARED_PREF除null之外的任何其他内容，因此您只需将其存储在null下。