I want to create vectors at 45 degree angles to a line

Question

I have the below classes for creating Vertices, Edges, and Midpoints of Edges on a canvas. I want to now create vectors at 45 degree angles to the edge at the midpoint. I have very little idea to do this at the moment. I would be very grateful if anyone could help.
public class Edge implements Serializable{
int edgeName;
Vertex first;
Vertex second;
Midpoint m;
double edgeLength;
  public Edge(Vertex end, Vertex otherEnd, Midpoint crossing) {
       this.first = end;
       this.second = otherEnd;
       this.m = crossing;
       this.edgeLength= getEdgeLength();
public class Vertex implements Serializable{
     //int name;
     float xpos;
     float ypos;
     Vector vertexEdges;
  public Vertex(//int ID,
            float x, float y) {
       //this.name = ID;
       this.xpos = x;
       this.ypos = y;
       vertexEdges = new Vector();
public class Midpoint{
int first;
int second;
//controlPoint controlPoint;
  public Midpoint(int x, int y) {
       this.first = x;
       this.second = y;
}

Answer 1

OK this is a shot in the dark but it makes sense.
Edge edge = new Edge()
public Vertex addDegreeAngleAtMidpoint(Edge edge, float degree, int lineLength){
    //calculate the slope of the line ( (y2-y1) / (x2-x1 )
   float slope = ((edge.secode.ypos - edge.first.ypos) / (edge.secode.xpos - edge.first.xpos)
   //now you know the slope of the line then calculate x degrees from the line
  //so the equation would be (cos degree = x/length) for the x value
  float x =  Math.cos(angle) * length;
  //so the equation would be (sin degree = y/length) for the y value
  float  y = math.sin(angle) * length;
  //calculate the slope of the vector ( (y2-y1) / (x2-x1 ) )
  float vectSlope = (y - edge.midpoint.first) / (x = edge.midpoint.secode);
  // get y intercept (y = mx+b => b = y -mx)
  float yIntercept = y - vectSlope*x;
  //get the point y = mx + yIntercept
  // any point plugged into this equation shold be degrees offset from the midpoint of the line
  // I did the hard part now you figure out the rest please. 
}