Problem converting degrees and radians

Question

I am programming a Java program that uses a ui that uses inheritance and polymorphism. It askes the user what shape would he/she like to input information on. Lets say they choose 1 for Line and then another ui apears (i.e. JOptionpane is being used) and the user may input the starting coord for line (x1, y1) and ending coord (x2, y2) or the user may input starting coords and (length and angle) of line. If the user chooses to enter starting and ending coord then the program outputs the starting and ending coord plus it outputs the Length and angle.
Here is the formula:
length = sqrt(( x2 - x1) ^2 + (y2 - y1) ^ 2)
alpha = atan((y2 - y1) /(x2 - x1))
angle must be in degrees before printing (angle * 180/3.14159)
Problem is the angle returns the wrong degrees back.
Can any one help with this problem THANKS!
Here is the formula:
x2 = x1 + length * cos(alpha);
y2 = y1 + length * sin(alpha);
angle must be in radians before calculations (angle * 180/3.14159)
Problem is that my points give me incorrect ending points.

Answer 1

Here is my code for class Line.
* Dwayne Brown
* Line class
package mypackage;
public class Line  extends Point
//fields
private int x2;
private int y2;
private double length;
private double angle;
private double alpha;
  //default constructor
  public Line()
  //implicit call to constructor
  }//end contructor
//constructor with arguments
  public Line(int xValue1, int yValue1, int xValue2, int yValue2)
  //implicit call to constructor
  //call super constructor to Point
  super(xValue1, yValue1);
  setX2(xValue2);
  setY2(yValue2);
  }//end of constructor
  //constructor with arguments
  public Line(int xValue1, int yValue1, double len, double ang)
  //implicit call to constructor
  //call super constructor to Point
  super(xValue1, yValue1);
  setLength(len);
  setAngle(ang);
  alpha = ang * Math.PI/180.0;
  }//end contructor
  //setX2
  public void setX2(int xValue2)
  //evaluate x2 value
  if(xValue2 > 0 || xValue2 < 0)
  x2 = xValue2;
  else
  //sets x2
  x2 = super.getX1() + (int)length * (int)alpha;
  }//end of setX2 method
  //setY2
  public void setY2(int yValue2)
  //evaluate x2 value
  if(yValue2 > 0 || yValue2 < 0)
  y2 = yValue2;
  else
  //sets y2
  y2 = super.getY1() + (int)length * (int)alpha;
  }//end of setY2 method
  //setLength
  public void setLength(double len)
    if(len != 0 )
    length = len;
    else
    //set length
    length = Math.sqrt( Math.pow((x2 - super.getX1()),2) +
    Math.pow(y2 - super.getY1(),2) );
    }//end of else statement
  }//end setLength method
  //setAngle
  public void setAngle(double ang)
    if(ang != 0)
    angle = ang;
    else
    alpha = Math.atan( (y2 - super.getY1() / x2 - super.getX1()) );
    angle = alpha / (Math.PI / 180.0);
    }//end of else statement
  }//end setAngle method
////////////////// getFunctions ///////////////////////
  public int getX2()
    return x2;
  }//end getX2 method
   public int getY2()
    return y2;
  }//end getY2 method
   public double getLength()
    return length;
  }//end getLength method
   public double getAngle()
    return angle;
  }//end getAngle method
//////////////////// toString /////////////////////////
//////////////////// getName //////////////////////////
  public String getName()
    return "Line"; 
  }//end of getName method
  public String toString()
    return getName()+super.toString()+"\nEnd Coordinat=("+x2+", "+y2+")"
    +"\nLine Length="+getLength()+"\nLine Angle with the x-axis="+getAngle();
  }//end toString method
}//end of class line