ReportCard.java

package com.example.android.reportcard;

import java.util.ArrayList;

/**
 * Created by David on 02/06/2017.
 */

public class ReportCard {
    private ArrayList<Grade> grades;
    private int numGrades;

    /**
     * Constructor for ReportCard class.
     */
    public ReportCard() {
        this.grades = new ArrayList<>();
        this.numGrades = 0;
    }

    /**
     * Adds a new grade to the current list of grades, if it does not already exist.
     *
     * @param newSubject: name of the subject.
     * @param newGrade:   grade for the subject.
     * @return true, if the grade has been added, or false, if the subject already existed.
     */
    public boolean setGrade(String newSubject, double newGrade) {
        boolean res = true;
        for (Grade grade : this.grades) {
            if (grade.getSubject().toLowerCase().equals(newSubject.toLowerCase())) {
                // Subject found. The grade will not be added.
                res = false;
                break;
            }
        }

        if (res) {
            // The grade is added because the subject has not been found in the list.
            Grade grade = new Grade(newSubject, newGrade);
            this.grades.add(grade);
            numGrades++;
        }

        return res;
    }

    /**
     * Modifies an existing grade.
     *
     * @param subject:  name of the subject.
     * @param newGrade: new grade for the subject.
     * @return true, if the grade has been modified, or false, if the subject does not exist.
     */
    public boolean modifyGrade(String subject, double newGrade) {
        boolean res = false;
        int n = 0;
        for (Grade grade : this.grades) {
            if (grade.getSubject().toLowerCase().equals(subject.toLowerCase())) {
                // Subject found. The grade is modified.
                grade.setGrade(newGrade);
                this.grades.set(n, grade);
                res = true;
                break;
            }
            n++;
        }
        return res;
    }

    /**
     * Deletes an existing grade.
     *
     * @param subject; name of the subject.
     * @return true, if the grade has been deleted, or false, if the subject does not exist.
     */
    public boolean deleteGrade(String subject) {
        boolean res = false;
        int n = 0;
        for (Grade grade : this.grades) {
            if (grade.getSubject().toLowerCase().equals(subject.toLowerCase())) {
                // Subject found. The grade is deleted.
                this.grades.remove(n);
                this.numGrades--;
                res = true;
                break;
            }
            n++;
        }
        return res;
    }

    /**
     * Looks for the grade of a subject.
     *
     * @param subject: name of the subject.
     * @return the grade fot the subject, if exists; -1 otherwise.
     */
    public double getGrade(String subject) {
        double res = -1;
        for (Grade grade : this.grades) {
            if (grade.getSubject().toLowerCase().equals(subject.toLowerCase())) {
                // Subject found. Return the grade for the subject.
                res = grade.getGrade();
                break;
            }
        }
        return res;
    }

    /**
     * @return the current number of subjects/grades.
     */
    public int getNumGrades() {
        return this.numGrades;
    }

    /**
     * @return the list of grades in a human-readable string.
     */
    @Override
    public String toString() {
        String gradesList = "";
        for (int n = 0; n < this.numGrades; n++) {
            // Writes the current line with the name of the subject and its grade.
            gradesList = gradesList + "Subject \"" + this.grades.get(n).getSubject() +
                    "\": grade " + this.grades.get(n).getGrade();

            // Adds a "new line" character if the current line is not the last one.
            if (n < (this.numGrades - 1)) gradesList = gradesList + "\n";
        }
        return gradesList;
    }

    /**
     * Class for representing a pair subject/grade.
     */
    private class Grade {
        private String subject;    // Name of the subject.
        private double grade;      // Grade for the subject.

        /**
         * Constructor for Grade class.
         *
         * @param subject: name of the subject.
         * @param grade:   grade for the subject.
         */
        public Grade(String subject, double grade) {
            this.subject = subject;
            this.grade = grade;
        }

        /**
         * @return the name of the subject.
         */
        public String getSubject() {
            return this.subject;
        }

        /**
         * @return the grade of the subject.
         */
        public double getGrade() {
            return this.grade;
        }

        /**
         * Sets the name of the subject.
         *
         * @param subject: name of the subject.
         */
        public void setSubject(String subject) {
            this.subject = subject;
        }

        /**
         * Sets the grade for the subject.
         *
         * @param grade: grade of the subject.
         */
        public void setGrade(double grade) {
            this.grade = grade;
        }
    }
}