activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.darrell.project2.MainActivity">

    <LinearLayout
        android:id="@+id/ll_currentUser"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/tv_currentUser"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Current User" />

        <ImageView
            android:id="@+id/iv_currentAvatar"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:cropToPadding="true"
            android:maxHeight="50px"
            app:srcCompat="@mipmap/ic_launcher" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/horizontalScrollView"
        android:layout_alignParentStart="true"
        android:layout_marginBottom="28dp"
        android:orientation="vertical"
        android:id="@+id/ll_login">

        <EditText
            android:id="@+id/et_username"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginStart="23dp"
            android:layout_marginTop="20dp"
            android:ems="10"
            android:hint="Enter Username"
            android:inputType="text"
            android:textAlignment="center"
            android:textStyle="bold|italic" />

        <EditText
            android:id="@+id/et_password"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:ems="10"
            android:hint="Enter Password"
            android:inputType="textPassword"
            android:textAlignment="center"
            android:textStyle="normal|bold|italic" />
    </LinearLayout>

    <HorizontalScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_centerVertical="true"
        android:fillViewport="false"
        android:id="@+id/horizontalScrollView">

        <LinearLayout
            android:id="@+id/ll_avatars"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:orientation="horizontal">

            <ImageView
                android:id="@+id/iv_avatar1"
                android:layout_width="124dp"
                android:layout_height="125dp"
                app:srcCompat="@mipmap/avatar1"
                android:onClick="avatar_onClick"/>

            <ImageView
                android:id="@+id/iv_avatar2"
                android:layout_width="124dp"
                android:layout_height="125dp"
                app:srcCompat="@mipmap/avatar2"
                android:onClick="avatar_onClick"/>

            <ImageView
                android:id="@+id/iv_avatar3"
                android:layout_width="124dp"
                android:layout_height="125dp"
                app:srcCompat="@mipmap/avatar3"
                android:onClick="avatar_onClick"/>

            <ImageView
                android:id="@+id/iv_avatar4"
                android:layout_width="124dp"
                android:layout_height="125dp"
                app:srcCompat="@mipmap/avatar4"
                android:onClick="avatar_onClick"/>

            <ImageView
                android:id="@+id/iv_avatar5"
                android:layout_width="124dp"
                android:layout_height="125dp"
                app:srcCompat="@mipmap/avatar5"
                android:onClick="avatar_onClick"/>
        </LinearLayout>
    </HorizontalScrollView>

    <LinearLayout
        android:id="@+id/ll_colorChoice"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/horizontalScrollView"
        android:orientation="horizontal">


        <TextView
            android:id="@+id/tv_colorChoice"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Choose Color" />

        <Button
            android:id="@+id/btn_yellow"
            style="@style/Widget.AppCompat.Button.Borderless.Colored"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Yellow"
            />

        <Button
            android:id="@+id/btn_red"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Red"
            />

        <Button
            android:id="@+id/btn_blue"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Blue" />

    </LinearLayout>

    <LinearLayout
        android:id="@+id/ll_createAcount"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:layout_below="@+id/ll_colorChoice"
        android:layout_alignParentStart="true"
        android:layout_marginTop="21dp">

        <Button
            android:id="@+id/btn_createAccount"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Create Account" />
    </LinearLayout>
</RelativeLayout>

MainActivity.java

package com.example.darrell.project2;

import android.content.Context;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;
import java.util.HashMap;

public class MainActivity extends AppCompatActivity {

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

       /* HashMap<Integer, Integer> mapViewIdToImageId = new HashMap<Integer, Integer>();
        mapViewIdToImageId.put(R.id.iv_avatar1, R.mipmap.avatar1);
        mapViewIdToImageId.put(R.id.iv_avatar2, R.mipmap.avatar2);
        mapViewIdToImageId.put(R.id.iv_avatar3, R.mipmap.avatar3);
        mapViewIdToImageId.put(R.id.iv_avatar4, R.mipmap.avatar4);
        mapViewIdToImageId.put(R.id.iv_avatar5, R.mipmap.avatar5);
        */

        SharedPreferences restoreAvatar = getSharedPreferences("MyPref", 0);
        u_currentAvatar = restoreAvatar.getInt("MyPref", u_currentAvatar);

       // if (restoreAvatar.getInt("Current Avatar", R.id.iv_avatar1) == R.id.iv_avatar1){
         //   iv_currentAvatar.setImageResource(R.mipmap.avatar1);
    } // end of onCreate

    public void avatar_onClick(View oView) {
        int selectedImage;
        int currentAvatar = 0;
        ImageView imgClicked = (ImageView) oView;

        ImageView iv_currentAvatar = (ImageView) findViewById(R.id.iv_currentAvatar);
        selectedImage = imgClicked.getId();

        //selectedImage = (ImageView) findViewById(R.id.iv_avatar1);

        //Toast.makeText(this, "Image ID: " + imgClicked.getId(), Toast.LENGTH_SHORT).show();
        //Toast.makeText(this, "IC ID: " + R.mipmap.avatar1, Toast.LENGTH_SHORT) .show();

        iv_currentAvatar.setImageResource(R.mipmap.avatar1);

        SharedPreferences.Editor avatarPref = getSharedPreferences("MyPref", MODE_PRIVATE).edit();

        if (selectedImage == R.id.iv_avatar1) {
            iv_currentAvatar.setImageResource(R.mipmap.avatar1);
            avatarPref.putInt("Current Avatar", currentAvatar);
            avatarPref.commit();
        } else if (selectedImage == R.id.iv_avatar2) {
            iv_currentAvatar.setImageResource(R.mipmap.avatar2);
            avatarPref.putInt("Current Avatar", currentAvatar);
            avatarPref.commit();
        } else if (selectedImage == R.id.iv_avatar3) {
            iv_currentAvatar.setImageResource(R.mipmap.avatar3);
            avatarPref.putInt("Current Avatar", currentAvatar);
            avatarPref.commit();
        } else if (selectedImage == R.id.iv_avatar4) {
            iv_currentAvatar.setImageResource(R.mipmap.avatar4);
            avatarPref.putInt("Current Avatar", currentAvatar);
            avatarPref.commit();
        } else if (selectedImage == R.id.iv_avatar5) {
            iv_currentAvatar.setImageResource(R.mipmap.avatar5);
            avatarPref.putInt("Current Avatar", currentAvatar);
            avatarPref.commit();
        }

    }// end of avatar onClick
}// end of class