Analysis
Well, first let's analyze the problem.
You need to take two pieces of data (the person's name, and their grade) and output a string containing both values, separated by enough characters (either "." or something else, perhaps).
So we want a function... a black box we push data into, and take information out of. What we put in is a name and a grade, and we get out a string.
| code: | String getFormattedString(String name, int grade) {
} |
That's just a shell, but when it comes to using the function, that's all we'll need to know. Of course, for it to be useful, you need something between the brackets.
This is what you're asking about. So first we need to figure out the length of the name and the length of the grade (it's probably between 0 and 100, so it might be 1 or 3 printed characters).
| code: | String getFormattedString(String name, int grade) {
int nameLen = name.length();
int gradeLen;
if (grade < 10)
gradeLen = 1;
else if (grade < 100)
gradeLen = 2;
else
gradeLen = 3;
} |
So now we know how how much of those 30 characters the two pieces of data will take up in the end result. Thus we can figure out the number of dots we'll need.
| code: | String getFormattedString(String name, int grade) {
int nameLen = name.length();
int gradeLen;
if (grade < 10)
gradeLen = 1;
else if (grade < 100)
gradeLen = 2;
else
gradeLen = 3;
int numOfDots = 30 - nameLen - gradeLen;
} |
So now we can just start at 1 and loop up until we get to that amount. We'll create a variable to store the dots in.
| code: | String getFormattedString(String name, int grade) {
int nameLen = name.length();
int gradeLen;
if (grade < 10)
gradeLen = 1;
else if (grade < 100)
gradeLen = 2;
else
gradeLen = 3;
int numOfDots = 30 - nameLen - gradeLen;
String dots = "";
for (int counter = 1; counter <= numOfDots; counter++)
dots = dots + "*";
} |
Now, to compose the final result, we simple add the dots to the name, and the grade to the end of that. Then we take that string and return it from our function. We "spit" it out the other side of our "black box".
| code: | String getFormattedString(String name, int grade) {
int nameLen = name.length();
int gradeLen;
if (grade < 10)
gradeLen = 1;
else if (grade < 100)
gradeLen = 2;
else
gradeLen = 3;
int numOfDots = 30 - nameLen - gradeLen;
String dots = "";
for (int counter = 1; counter <= numOfDots; counter++)
dots = dots + "*";
String finalResult = name + dots + grade;
return finalResult;
} |
We can then use this as follows:
| code: | class Exercise {
public static String getFormattedString(String name, int grade) {
int nameLen = name.length();
int gradeLen;
if (grade < 10)
gradeLen = 1;
else if (grade < 100)
gradeLen = 2;
else
gradeLen = 3;
int numOfDots = 30 - nameLen - gradeLen;
String dots = "";
for (int counter = 1; counter <= numOfDots; counter++)
dots = dots + "*";
}
public static void main(String[] args) {
String output = getFormattedString("John Doe", 87);
System.out.println(output);
}
} |
Object-Oriented Design
Further analyzing this problem, the two pieces of data are related. Together they describe a student. This is our "thing" for this program. What we do to this thing is take the data that represents it (name and grade) and stick them together in a certain way.
So we have a thing (or "object") in the form of a student, and an action ("method") in the form of getting our formatted string. We need a way to describe a student object, and the action that it can perform on itself.
In Java (and many other languages) we call this a "class". The Student class now has attributes called name and grade. These we say are private to the class. That is, only a student can know its own name and grade. It can elect to share that information with others, but they cannot access it without permission.
| code: | class Exercise {
class Student {
private String name;
private int grade;
}
} |
Ok, so that's all well and good, but this doesn't do much of anything at all, and nothing useful as far as we're concerned.
We can, however, create a new student that will have a name and a grade. Of course, since we haven't provided any information as to what those are, the student object will be meaningless. To provide some initial information, we need a special method called a "constructor".
The constructor will take as input an initial name, and an initial grade, and what makes it special is that it doesn't return anything. Not even "void". Of course, the constructor is "public", so that anyone can create a new student.
Inside the constructor, we'll set the student's name and grade.
A note on Java, specifically: the constructor method always has the same name as the class.
| code: | class Exercise {
class Student {
private String name;
private int grade;
public Student(String initialName, int initialGrade) {
name = initialName;
grade = initialGrade;
}
}
} |
So now we can create a new Student in our "main" method.
| code: | class Exercise {
class Student {
private String name;
private int grade;
public Student(String initialName, int initialGrade) {
name = initialName;
grade = initialGrade;
}
}
public static void main(String[] args) {
Student johnDoe = new Student("John Doe", 89);
}
} |
Again, we can't really do anything with this, so we have to add a public method to get our specially formatted string, as detailed in the getFormattedString method. In the case of the Student class, we'll use the method name toString. This is the method that is, by convention, used when another class is trying to figure out what an object looks like as a string. For instance, System.out.println.
| code: | class Exercise {
class Student {
private String name;
private int grade;
public Student(String initialName, int initialGrade) {
name = initialName;
grade = initialGrade;
}
public String toString() {
int nameLen = name.length();
int gradeLen;
if (grade < 10)
gradeLen = 1;
else if (grade < 100)
gradeLen = 2;
else
gradeLen = 3;
int numOfDots = 30 - nameLen - gradeLen;
String dots = "";
for (int counter = 1; counter <= numOfDots; counter++)
dots = dots + "*";
String finalResult = name + dots + grade;
return finalResult;
}
}
public static void main(String[] args) {
Student johnDoe = new Student("John Doe", 89);
System.out.println(johnDoe);
}
} |
|
because in the following code...
if user determines the number of sets to be 5 the following will print out..
i hope it`s not a lot to ask for.. i`m a beginner at programming loops.. so there is still a lot i need to learn..but i`m sure will all these col programmers i`ll be fine.. wow this is starting to sound g.ay.. i`ll stop..
eh
help?
