Contoh Register Activity untuk Tutorial Simple Login menggunakan Shared Preferences di https://medium.com/@vickyfarenza/tutorial-penggunaan-shared-preferences-pada-android-eddc300d7509

activity_register.xml

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".RegisterActivity">
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
            <LinearLayout
                android:layout_centerInParent="true"
                android:layout_marginTop="230dp"
                android:layout_marginEnd="50dp"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:padding="18dp"
                android:orientation="vertical">
                <EditText
                    android:id="@+id/et_emailSignup"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:hint="@string/label_user"
                    android:inputType="textEmailAddress"
                    android:maxLines="1"
                    android:singleLine="true"/>
                <EditText
                    android:id="@+id/et_passwordSignup"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:hint="Password"
                    android:inputType="textPassword"
                    android:maxLines="1"
                    android:singleLine="true" />
                <EditText
                    android:id="@+id/et_passwordSignup2"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_marginBottom="30dp"
                    android:hint="@string/label_confirm_password"
                    android:inputType="textPassword"
                    android:maxLines="1"
                    android:singleLine="true"
                    android:imeActionId="6"
                    android:imeActionLabel="@string/label_signup"
                    android:imeOptions="actionUnspecified" />
                <Button
                    android:id="@+id/button_signupSignup"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:text="Sign Up" />
            </LinearLayout>
    </RelativeLayout>
</ScrollView>

RegisterActivity.java

package farenza.tutorial.simplelogin;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.KeyEvent;
import android.view.View;
import android.view.inputmethod.EditorInfo;
import android.widget.EditText;
import android.widget.TextView;

public class RegisterActivity extends AppCompatActivity {

    private EditText mViewUser, mViewPassword, mViewRepassword;

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

        /* Menginisialisasi variable dengan Form User, Form Password, dan Form Repassword
        dari Layout RegisterActivity */
        mViewUser =findViewById(R.id.et_emailSignup);
        mViewPassword =findViewById(R.id.et_passwordSignup);
        mViewRepassword =findViewById(R.id.et_passwordSignup2);

        /* Menjalankan Method razia() jika merasakan tombol SignUp di keyboard disentuh */
        mViewRepassword.setOnEditorActionListener(new TextView.OnEditorActionListener() {
            @Override
            public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
                if (actionId == EditorInfo.IME_ACTION_DONE || actionId == EditorInfo.IME_NULL) {
                    razia();
                    return true;
                }
                return false;
            }
        });
        /* Menjalankan Method razia() jika merasakan tombol SignUp disentuh */
        findViewById(R.id.button_signupSignup).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                razia();
            }
        });
    }

    /** Men-check inputan User dan Password dan Memberikan akses ke MainActivity */
    private void razia(){
        /* Mereset semua Error dan fokus menjadi default */
        mViewUser.setError(null);
        mViewPassword.setError(null);
        mViewRepassword.setError(null);
        View fokus = null;
        boolean cancel = false;

        /* Mengambil text dari Form User, Password, Repassword dengan variable baru bertipe String*/
        String repassword = mViewRepassword.getText().toString();
        String user = mViewUser.getText().toString();
        String password = mViewPassword.getText().toString();

        /* Jika form user kosong atau MEMENUHI kriteria di Method cekUser() maka, Set error di Form-
         * User dengan menset variable fokus dan error di Viewnya juga cancel menjadi true*/
        if (TextUtils.isEmpty(user)){
            mViewUser.setError("This field is required");
            fokus = mViewUser;
            cancel = true;
        }else if(cekUser(user)){
            mViewUser.setError("This Username is already exist");
            fokus = mViewUser;
            cancel = true;
        }

        /* Jika form password kosong dan MEMENUHI kriteria di Method cekPassword maka,
         * Reaksinya sama dengan percabangan User di atas. Bedanya untuk Password dan Repassword*/
        if (TextUtils.isEmpty(password)){
            mViewPassword.setError("This field is required");
            fokus = mViewPassword;
            cancel = true;
        }else if (!cekPassword(password,repassword)){
            mViewRepassword.setError("This password is incorrect");
            fokus = mViewRepassword;
            cancel = true;
        }

        /** Jika cancel true, variable fokus mendapatkan fokus. Jika false, maka
         *  Kembali ke LoginActivity dan Set User dan Password untuk data yang terdaftar */
        if (cancel){
            fokus.requestFocus();
        }else{
            Preferences.setRegisteredUser(getBaseContext(),user);
            Preferences.setRegisteredPass(getBaseContext(),password);
            finish();
        }
    }

    /** True jika parameter password sama dengan parameter repassword */
    private boolean cekPassword(String password, String repassword){
        return password.equals(repassword);
    }

    /** True jika parameter user sama dengan data user yang terdaftar dari Preferences */
    private boolean cekUser(String user){
        return user.equals(Preferences.getRegisteredUser(getBaseContext()));
    }
}