public Shape {
private final int x;
private final int y;
private final double radius;
private Shape(Builder builder) {
x = builder.x;
y = builder.y;
radius = builder.radius;
}
public static class Builder {
private final int x;
private final int y;
private double radius;
public Builder(int x, int y) {
this.x = x;
this.y = y;
}
public Builder radius(double radius) {
this.radius = radius;
return this;
}
public Shape build() {
return new Shape(this);
}
}
}
//in client code
Shape rectangle = new Shape.Builder(x,y).build();
Shape circle = new Shape.Builder(x,y).radius(radiusValue).build();
http://stackoverflow.com/questions/13885836/factory-in-java-when-concrete-objects-take-different-constructor-parameters