module2.lst

Mcgraw-Hill - Java 2 - A Beginner S Guide, 2Nd Ed - 2003 -prog.

listing 1
/*    
   Compute the number of cubic inches 
   in 1 cubic mile. 
*/    
class Inches {    
  public static void main(String args[]) {    
    long ci; 
    long im; 
   
    im = 5280 * 12; 
 
    ci = im * im * im; 
   
    System.out.println("There are " + ci + 
                       " cubic inches in cubic mile."); 
   
  }    
}

listing 2
/*    
   Use the Pythagorean theorem to find 
   find the length of the hypotenuse 
   given the lengths of the two opposing 
   sides. 
*/    
class Hypot {    
  public static void main(String args[]) {    
    double x, y, z; 
 
    x = 3; 
    y = 4; 
 
    z = Math.sqrt(x*x + y*y); 
 
    System.out.println("Hypotenuse is " +z); 
  }    
}

listing 3
// Character variables can be handled like integers.  
class CharArithDemo { 
  public static void main(String args[]) { 
    char ch; 
 
    ch = 'X'; 
    System.out.println("ch contains " + ch); 
 
    ch++; // increment ch 
    System.out.println("ch is now " + ch); 
 
    ch = 90; // give ch the value Z 
    System.out.println("ch is now " + ch); 
  } 
}

listing 4
// Demonstrate boolean values. 
class BoolDemo { 
  public static void main(String args[]) { 
    boolean b; 
 
    b = false; 
    System.out.println("b is " + b); 
    b = true; 
    System.out.println("b is " + b); 
 
    // a boolean value can control the if statement 
    if(b) System.out.println("This is executed."); 
 
    b = false; 
    if(b) System.out.println("This is not executed."); 
 
    // outcome of a relational operator is a boolean value 
    System.out.println("10 > 9 is " + (10 > 9)); 
  } 
}

listing 5
/* 
   Project 2-1 
 
   Compute the distance to a lightening 
   strke whose sound takes 7.2 seconds 
   to reach you. 
*/     
class Sound {     
  public static void main(String args[]) {     
    double dist; 
 
    dist = 7.2 * 1100; 
 
    System.out.println("The lightening is " + dist +  
                       " feet away.");  
    
  }     
}

listing 6
// Demonstrate escape sequences in strings. 
class StrDemo {    
  public static void main(String args[]) {    
    System.out.println("First line\nSecond line"); 
    System.out.println("A\tB\tC"); 
    System.out.println("D\tE\tF"); 
  }    
}

listing 7
// Demonstrate dynamic initialization. 
class DynInit { 
    public static void main(String args[]) { 
      double radius = 4, height = 5; 
 
      // dynamically initializ volume 
      double volume = 3.1416 * radius * radius * height; 
 
      System.out.println("Volume is " + volume); 
    } 
}

listing 8
// Demonstrate block scope. 
class ScopeDemo { 
  public static void main(String args[]) { 
    int x; // known to all code within main 
 
    x = 10; 
    if(x == 10) { // start new scope
      int y = 20; // known only to this block 
 
       // x and y both known here. 
       System.out.println("x and y: " + x + " " + y); 
       x = y * 2; 
    } 
    // y = 100; // Error! y not known here  
 
    // x is still known here. 
    System.out.println("x is " + x); 
  } 
}

listing 9
// Demonstrate lifetime of a variable. 
class VarInitDemo { 
  public static void main(String args[]) { 
    int x;  
 
    for(x = 0; x < 3; x++) { 
      int y = -1; // y is initialized each time block is entered 
      System.out.println("y is: " + y); // this always prints -1 
      y = 100;  
      System.out.println("y is now: " + y); 
    } 
  } 
}

listing 10
/*  
   This program attempts to declared a variable 
   in an inner scope with the same name as one 
   defined in an outer scope. 
 
   *** This program will not compile. *** 
*/  
class NestVar {  
  public static void main(String args[]) {  
    int count;  
 
    for(count = 0; count < 10; count = count+1) { 
      System.out.println("This is count: " + count);  
     
      int count; // illegal!!! 
      for(count = 0; count < 2; count++) 
        System.out.println("This program is in error!"); 
    } 
  }  
}

listing 11
// Demonstrate the % operator. 
class ModDemo {    
  public static void main(String args[]) {    
    int iresult, irem; 
    double dresult, drem; 
 
    iresult = 10 / 3; 
    irem = 10 % 3; 
 
    dresult = 10.0 / 3.0; 
    drem = 10.0 % 3.0;  
 
    System.out.println("Result and remainder of 10 / 3: " + 
                       iresult + " " + irem); 
    System.out.println("Result and remainder of 10.0 / 3.0: " + 
                       dresult + " " + drem); 
 
  }    
}

listing 12
// Demonstrate the relational and logical operators. 
class RelLogOps {    
  public static void main(String args[]) {    
    int i, j; 
    boolean b1, b2; 
 
    i = 10; 
    j = 11; 
    if(i < j) System.out.println("i < j"); 
    if(i <= j) System.out.println("i <= j"); 
    if(i != j) System.out.println("i != j"); 
    if(i == j) System.out.println("this won't execute"); 
    if(i >= j) System.out.println("this won't execute"); 
    if(i > j) System.out.println("this won't execute"); 
 
    b1 = true; 
    b2 = false; 
    if(b1 & b2) System.out.println("this won't execute"); 
    if(!(b1 & b2)) System.out.println("!(b1 & b2) is true"); 
    if(b1 | b2) System.out.println("b1 | b2 is true"); 
    if(b1 ^ b2) System.out.println("b1 ^ b2 is true"); 
  }    
}

listing 13
// Demonstrate the short-circuit operators. 
class SCops {    
  public static void main(String args[]) {    
    int n, d, q; 
 
    n = 10; 
    d = 2; 
    if(d != 0 && (n % d) == 0) 
      System.out.println(d + " is a factor of " + n); 
 
    d = 0; // now, set d to zero 
 
    // Since d is zero, the second operand is not evaluated. 
    if(d != 0 && (n % d) == 0) 
      System.out.println(d + " is a factor of " + n);  
     
    /* Now, try same thing without short-circuit operator. 
       This will cause a divide-by-zero error. 
    */ 
    if(d != 0 & (n % d) == 0) 
      System.out.println(d + " is a factor of " + n); 
  }    
}

listing 14
// Side-effects can be important. 
class SideEffects {    
  public static void main(String args[]) {    
    int i; 
 
    i = 0; 
 
    /* Here, i is still incremented even though 
       the if statement fails. */ 
    if(false & (++i < 100)) 
       System.out.println("this won't be displayed"); 
    System.out.println("if statements executed: " + i); // displays 1 
 
    /* In this case, i is not incremented because 
       the short-circuit operator skips the increment. */ 
    if(false && (++i < 100)) 
      System.out.println("this won't be displayed"); 
    System.out.println("if statements executed: " + i); // still 1 !! 
  }    
}

listing 15
// Demonstate automatic conversion from long to double. 
class LtoD {    
  public static void main(String args[]) {    
    long L; 
    double D; 
   
    L = 100123285L; 
    D = L; 
   
    System.out.println("L and D: " + L + " " + D); 
   
  }    
}

listing 16
// *** This program will not compile. *** 
class LtoD {    
  public static void main(String args[]) {    
    long L; 
    double D; 
   
    D = 100123285.0; 
    L = D; // Illegal!!! 
   
    System.out.println("L and D: " + L + " " + D); 
   
  }    
}

listing 17
// Demonstrate casting.    
class CastDemo {    
  public static void main(String args[]) {    
    double x, y; 
    byte b; 
    int i; 
    char ch; 
 
    x = 10.0; 
    y = 3.0; 
 
    i = (int) (x / y); // cast double to int 
    System.out.println("Integer outcome of x / y: " + i); 
 
    i = 100; 
    b = (byte) i;  
    System.out.println("Value of b: " + b); 
 
    i = 257; 
    b = (byte) i;  
    System.out.println("Value of b: " + b); 
 
    b = 88; // ASCII code for X 
    ch = (char) b; 
    System.out.println("ch: " + ch);  
  }    
}

listing 18
/* 
   Project 2-2 
 
   Print a truth table for the logical operators. 
*/ 
class LogicalOpTable {    
  public static void main(String args[]) {    
 
    boolean p, q; 
 
    System.out.println("P\tQ\tAND\tOR\tXOR\tNOT"); 
 
    p = true; q = true; 
    System.out.print(p + "\t" + q +"\t"); 
    System.out.print((p&q) + "\t" + (p|q) + "\t"); 
    System.out.println((p^q) + "\t" + (!p)); 
 
    p = true; q = false; 
    System.out.print(p + "\t" + q +"\t"); 
    System.out.print((p&q) + "\t" + (p|q) + "\t"); 
    System.out.println((p^q) + "\t" + (!p)); 
 
    p = false; q = true; 
    System.out.print(p + "\t" + q +"\t"); 
    System.out.print((p&q) + "\t" + (p|q) + "\t"); 
    System.out.println((p^q) + "\t" + (!p)); 
 
    p = false; q = false; 
    System.out.print(p + "\t" + q +"\t"); 
    System.out.print((p&q) + "\t" + (p|q) + "\t"); 
    System.out.println((p^q) + "\t" + (!p)); 
  }    
}

listing 19
// A promotion surprise! 
class PromDemo {    
  public static void main(String args[]) {    
    byte b; 
    int i; 
   
    b = 10; 
    i = b * b; // OK, no cast needed 
 
    b = 10; 
    b = (byte) (b * b); // cast needed!! 
 
    System.out.println("i and b: " + i + " " + b); 
  }    
}

listing 20
// Using a cast. 
class UseCast {    
  public static void main(String args[]) {    
    int i; 
 
    for(i = 0; i < 5; i++) { 
      System.out.println(i + " / 3: " + i / 3); 
      System.out.println(i + " / 3 with fractions: " 
                         + (double) i / 3); 
      System.out.println(); 
    } 
  }    
}