public class FunWithArrays {
public static double calcAverage (int a, int b, int c, int d, int e, int f, int g, int h, int i, int j ) {
return (a + b + c + d + e + f + g + h + i + j) / 10.0;
}
public static double calcAverage (int[] ia) {
int x, sum = 0;
for ( x = 0; x < ia.length; x++ )
sum = sum + ia[x];
return sum / (double)ia.length;
}
public static double calcAverage (int[] ia, int n) {
int x, sum = 0;
if ( n > ia.length)
return -1.0;
for ( x = 0; x < n; x++ )
sum = sum + ia[x];
return sum / (double)n;
}
public static void main (String[] args) {
int x;
int[] a = new int[10];
// Horrible test of horrible first version!
System.out.println(calcAverage(10,20,30,40,50,60,70,80,90,100));
// Generate ramdom test grades in the inclusive range 60 - 100
for ( x = 0; x < a.length; x++)
a[x] = (int)(Math.random() * 41 + 60);
// Show me the test grades
for ( x = 0; x < a.length; x++)
System.out.println("a[" + x + "] = " + a[x]);
System.out.println("The average of the whole array is " + calcAverage(a));
System.out.println("The average of the first 3 elements is " + calcAverage(a, 3));
System.out.println("This should be -1.0. Is it? " + calcAverage(a, 11));
}
}
public class testPerson {
public static void main (String[] args) {
Person me, you;
me = new Person("Bill", "Jojo", 50);
you = new Person();
you.setGivenName("Other");
you.setSurname("Person");
you.setAge(35);
System.out.println("me.getGivenName() = " + me.getGivenName());
System.out.println("me.getSurname() = " + me.getSurname());
System.out.println("me.getAge() = " + me.getAge() + "\n");
System.out.println("you.getGivenName() = " + you.getGivenName());
System.out.println("you.getSurname() = " + you.getSurname());
System.out.println("you.getAge() = " + you.getAge() + "\n");
// This calls toString()!
System.out.println(me);
System.out.println(you);
}
}
Converting Strings and Numbers (SSN Style)
public class Ssn {
public static void main (String[] args) {
String stringssn;
int ssn, f, m, l;
ssn = 123456789;
// ssn = 123050067; // testing with zeroes
f = ssn / 1000000; // 123
ssn = ssn % 1000000; // 456789
m = ssn / 10000; // 45
l = ssn % 10000; // 6789
System.out.println("f = " + f);
System.out.println("m = " + m);
System.out.println("l = " + l);
System.out.printf("%03d-%02d-%04d%n", f, m ,l);
stringssn = String.format("%03d-%02d-%04d%n", f, m ,l);
System.out.printf(stringssn);
}
}
Example 2: SSN formatting using integers.
public class Ssn2 {
public static void main (String[] args) {
// 023050089
String ssn = "023050089", stringssn;
String f, m, l;
f = ssn.substring(0,3);
m = ssn.substring(3,5);
l = ssn.substring(5);
System.out.println("f = " + f);
System.out.println("m = " + m);
System.out.println("l = " + l);
stringssn = f + "-" + m + "-" + l;
System.out.println(stringssn);
}
}
Example 3: SSN formatting using String.
Fun Scanner stuff:
import java.util.Scanner;
public class ScannerStuff
{
public static Scanner kb = new Scanner(System.in);
public static void main (String[] args)
{
int x, y;
double d;
System.out.print("Enter a value for x: ");
x = kb.nextInt();
System.out.print("Enter a value for y: ");
y = kb.nextInt();
//System.out.print("Enter a value for d: ");
//d = kb.nextDouble();
System.out.println("x is " + x);
System.out.println("y is " + y);
System.out.println(x + " to the " + y + " is " + Math.pow(x,y));
}
}
Fun conditional stuff:
import java.util.Scanner;
public class Conditional {
static Scanner kb = new Scanner(System.in);
public static void main(String[] args) {
int i;
System.out.println("Enter an integer: ");
i = kb.nextInt();
if ( i < 0 ) {
System.out.println(i + " is negative.");
System.out.println("Yep, that's right...");
} else if ( i > 0 )
System.out.println(i + " is positive.");
else
System.out.println(i + " is zero.");
if ( i > 0 )
System.out.println(i + " is positive.");
else if ( i < 0 )
System.out.println(i + " is negative.");
else
System.out.println(i + " is zero.");
}
}
Fun iterative stuff:
import java.util.Scanner;
public class Conditional2 {
static Scanner kb = new Scanner(System.in);
public static void main(String[] args) {
int x;
/* while loop to do even/odd */
x = 0;
while ( x <= 10 ) {
if ( x % 2 == 0 )
System.out.println(x + " is an Even number!");
else
System.out.println(x + " is an Odd number!");
x++;
}
System.out.println("The value of x is " + x);
/* for loop to do the same */
for (x = 0 ; x <= 10; x++)
if ( x % 2 == 0 )
System.out.println(x + " is an Even number!");
else
System.out.println(x + " is an Odd number!");
System.out.println("The value of x is " + x);
}
}
EOF stuff
import java.util.Scanner;
public class Eof {
static Scanner kb = new Scanner(System.in);
public static void main(String[] args) {
String line;
int x;
System.out.print("Enter a string (CTRL-D to end): ");
while ( kb.hasNext() )
{
x = kb.nextInt(); // read the line
//System.out.println("Input was " + line.length() + " characters long.");
System.out.println("Input was " + x);
System.out.print("Enter a string (CTRL-D to end): ");
}
}
}
This is just a bad idea... Using Strings for ints while expecting an English response that we are done...
Just bad...
import java.util.Scanner;
public class Obtuse {
static Scanner kb = new Scanner(System.in);
public static void main(String[] args) {
String line;
int x;
System.out.print("Enter an integer (enter \"done\" when complete): ");
line = kb.nextLine();
//while ( ! line.equals("done") )
while ( line.compareToIgnoreCase("done") != 0)
{
x = Integer.parseInt(line);
System.out.println("Input was " + x + ".");
System.out.print("Enter an integer (enter \"done\" when complete): ");
line = kb.nextLine();
}
}
}
EOF look (like above) but with double and printf.
import java.util.Scanner;
public class Printf {
static Scanner kb = new Scanner(System.in);
public static void main(String[] args) {
double x;
System.out.print("Enter an double (CTRL-D to end): ");
while ( kb.hasNext() )
{
x = kb.nextDouble(); // read the line
System.out.printf("Input to two decimal places is %.2f%n", x);
System.out.print("Enter a double (CTRL-D to end): ");
}
}
}
Fun with floating point numbers...
public class Broken {
public static void main(String[] args) {
int x;
double f = 0;
for ( x = 1; x <= 20; x++) {
f = f + 0.1;
System.out.println(f);
}
}
}
Fun with methods...
public class MoreMethods
{
public static int sum(int a, int b) {
return a + b;
}
public static int product (int a, int b) {
return a * b;
}
public static void main(String[] args) {
int x, y, s;
x = 10;
y = 15;
System.out.println("The sum of x and y is " + sum(x,y));
System.out.println("The product of x and y is " + product(x,y));
}
}
Oh no! Even more fun with methods!
public class MyMethods {
public static void main(String[] args) {
char c;
c = ';';
if ( myIsLetter(c) )
System.out.println(c + " is a letter.");
if ( myIsDigit(c) )
System.out.println(c + " is a digit.");
if ( myIsLetterOrDigit(c) )
System.out.println(c + " is a letter or digit.");
else
System.out.println(c + " is not a letter or digit.");
if ( myIsLowerCase(c) )
System.out.println(c + " is lower case.");
if ( myIsUpperCase(c) )
System.out.println(c + " is upper case.");
}
public static boolean myIsDigit(char ch) {
return ch >= '0' && ch <= '9';
}
public static boolean myIsLetter(char ch) {
return myIsUpperCase(ch) || myIsLowerCase(ch);
}
public static boolean myIsLetterOrDigit(char ch) {
return myIsLetter(ch) || myIsDigit(ch);
}
public static boolean myIsUpperCase(char ch) {
return ch >= 'A' && ch <= 'Z';
}
public static boolean myIsLowerCase(char ch) {
return ( ch >= 'a' && ch <= 'z' );
}
}
Loops and strings and things...
import java.util.Scanner;
public class string {
public static Scanner kb = new Scanner(System.in);
public static void dumpString(String str) {
for ( int x = 0; x < str.length(); x++)
System.out.println("str.charAt(" + x + ") is \"" + str.charAt(x) + "\".");
}
public static void main(String[] args) {
String s = "This is a string.";
System.out.print("Enter a string: ");
while (kb.hasNext()) {
s = kb.nextLine();
dumpString(s);
System.out.print("Enter a string: ");
}
}
}