Saving the results from editText into a List in object class

Question

I am trying to solve a problem I have been stuck on for a while. I am trying to save the results from a user submit to a list. I am able to do that but when I leave to a previous oage in the app and come back to the page all of the data is gone. I am working in android studios. I have a User object class that I am storing the data for indivisual users of the app below. Can someone help me with how I can save the results of the user input in a list of some sorts. This is my User.java File package com.example.fitnessapplication;

import java.util.Collections; import java.util.List;

public class User {

private String fullName, age, email;
private String gender, address;

public User() {
}

public User(String fullName, String age, String email)
{
    this.fullName = fullName;
    this.age = age;
    this.email = email;

    gender = "";
    address = "";

}



public String getFullName() {
    return fullName;
}

public void setFullName(String fullName) {
    this.fullName = fullName;
}

public String getAge() {
    return age;
}

public void setAge(String age) {
    this.age = age;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

public String getGender() {
    return gender;
}

public void setGender(String gender) {
    this.gender = gender;
}

public String getAddress() {
    return address;
}

public void setAddress(String address) {
    this.address = address;
}

this is my main Goals.java

file package com.example.fitnessapplication;

import android.graphics.Paint; import android.os.Bundle; import android.view.View; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.EditText; import android.widget.ListView; import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;

import java.util.ArrayList; import java.util.List;

public class Goals extends AppCompatActivity{

List<String>  toDoList;
ArrayAdapter<String> arrayAdapter;
ListView listView;
EditText editText;

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

    toDoList = new ArrayList<>();

    arrayAdapter = new ArrayAdapter<>(this,R.layout.list_view_layout, toDoList);
    listView = findViewById(R.id.id_list_view);

    listView.setAdapter(arrayAdapter);
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
            TextView textView = (TextView) view;
            textView.setPaintFlags(textView.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
        }
    });

    editText = findViewById(R.id.id_edit_text);
}

public void addItemToList(View view){
    toDoList.add(editText.getText().toString());
    arrayAdapter.notifyDataSetChanged();
    editText.setText("");
}

}

this is my xml activity_goals.xml

<RelativeLayout 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=".Goals" >

<LinearLayout
    android:id="@+id/id_bottom_selection"
    android:layout_width="match_parent"
    android:padding="10dp"
    android:layout_alignParentBottom="true"
    android:layout_height="wrap_content">
    <EditText
        android:id="@+id/id_edit_text"
        android:layout_width="0dp"
        android:layout_weight = "1"
        android:layout_marginRight="10dp"
        android:layout_height="wrap_content"/>
    <Button
        android:onClick="addItemToList"
        android:layout_width="wrap_content"
        android:text="Add"
        android:layout_height="wrap_content"/>
</LinearLayout>

<LinearLayout
    android:layout_above="@+id/id_bottom_selection"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#eee">
    <ListView
        android:id="@+id/id_list_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </ListView>
</LinearLayout>

I am expecting whenever I make a new text view for the goal setting portion for it to still be there once I leave and come back to the page.

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