Defining Classes I - Absolute Java - page 214

Display 4.9 Yet Another Date Class (part 4 of 4)

90 return ( (monthInt >= 1) && (monthInt <= 12) &&

91 (dayInt >= 1) && (dayInt <= 31) &&

92 (yearInt >= 1000) && (yearInt <= 9999) );

93 }

94 private String monthString( int monthNumber)

95 {

96 switch (monthNumber)

97 {

98 case 1:

99 return "January";

100 case 2:

101 return "February";

102 case 3:

103 return "March";

104 case 4:

105 return "April";

106 case 5:

107 return "May";

108 case 6:

109 return "June";

110 case 7:

111 return "July";

112 case 8:

113 return "August";

114 case 9:

115 return "September";

116 case 10:

117 return "October";

118 case 11:

119 return "November";

120 case 12:

121 return "December";

122 default :

123 System.out.println("Fatal Error");

124 System.exit(0);

125 return "Error"; //to keep the compiler happy

126 }

127 }

128 }

The way that a well-designed class definition uses private instance variables and
public accessor and mutator methods to implement the principle of encapsulation is
diagrammed in Display 4.10 .