public void setAttributeName(dtype attributeName) { ...<chk> <set value>... }

Week 4: Writing classes/09a. Setting Methods

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+The principle of set methods is the same as that of observation methods: 
+they allow the client to CHANGE the STATE of the OBJECT.
+OFTEN, setting methods are of the 'void' type, since their purpose is to set the value of an attribute.
+
+Of course, the type can be something other than void, for example, a boolean type setting method could 
+return true or false depending on whether the given value was allowed or not.
+
+
+
+Consider the class ExamResult, which has a setting method for the attribute grade added to it: 
+Before setting the value of the attribute, it is checked that the given value is within the allowed range.
+
+The method is named in the form setAttributeValue. 
+The setting is done in a familiar way from the constructor, using the keyword 'this':
+
+class ExamResult {
+    // PRIVATE ATTRIBUTES
+    private String student;
+    private int grade;
+
+    //CONSTRUCTOR
+    public ExamResult(String student, int grade) {
+        this.student = student;
+        this.grade = grade;
+    }
+
+    // GET
+    public int getGrade() {
+        return grade;
+    }
+
+    //SET
+    public void setGrade(int grade) {
+        if (grade >= 1 && grade <= 5) {
+            this.grade = grade;
+        }
+    }
+}
+
+
+
+ 
+
+Now the client can set a new value for the rating by calling a method.
+
+public class TestClass {
+    public static void main(String[] args) {
+        ExamResult r = new ExamResult("Ann", 3);
+
+        // SET/UPDATE ATTRIBUTE HERE
+        r.setGrade(5);
+        System.out.println(r.getGrade());
+
+        // VS
+        // This is not accepted, so the grade does not change
+        r.setGrade(-1);
+        System.out.println(r.getGrade());
+    }
+}
+Program outputs:
+5
+5
+
+ 
+
+In the Student class, it would be easiest for the customer if points could be added to the regulation 
+by one method in addition to the given number 
+- often the number of credits increases by a certain value when a course is completed. 
+So let's implement methods in the class for both setting and adding credits. 
+At the same time, the other missing set and get methods are added to the class.
+
+class Student {
+    private String name;
+    private String studentId;
+    private int studyPoints;
+    
+    public Student(String name, String studentId, int studyPoints) {
+        this.name = name;
+        this.studentId = studentId;
+        this.studyPoints = studyPoints;
+    }
+   
+    public String getName() {
+        return name;
+    }
+
+    public String getStudentId() {
+        return studentId;
+    }
+
+    public int getStudyPoints() {
+        return this.studyPoints;
+    }
+        
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public void setStudentId(String studentId) {
+        this.studentId = studentId;
+    }
+
+    public void setStudyPoints(int studyPoints) {
+        if (studypoints >= 0) {
+            this.studypoitns = studypoints;
+        }
+    }
+    
+    public void addPoints(int completionPoints) {
+        if (completionPoints >= 0) {
+            this.studypoints += completionPoints;
+        }
+    }
+}
+
+
+