Android Roboguice Use Guide (4) linked bindings

One of the most commonly used bindings in Roboguice is linked bindings, which maps a type to its implementation. Here we use the class in the two-dimensional graphics library of the guide bee as an example, the use of the two-dimensional graphics library of the guide bee can be seen in the Android Concise development Tutorial Eight: The Guide bee two-dimensional graphic drawing instance function definition.

Use the following classes IShape, Rectangle, MyRectangle, MySQUARE, whose inheritance relationship is shown in the following illustration:

The following code maps IShape to MyRectangle

Public 

class Graphics2dmodule extends abstractandroidmodule{     
          
 @Override 
 protected void Configure () {     
          
 Bind (Ishape.class). to (Myrectangle.class);     
          
 }     
}

At this point, if you use Injector.getinstance (ishape.class) or injector you encounter a dependency on IShape place, it will use MyRectangle. You can map a type to any of its subclasses or to all classes that implement that type of interface. You can also map a real class (a non-interface) to its subclasses, such as

Bind (Myrectangle.class). to (Mysquare.class);

The following example uses the @Inject application IShape.

public class Linkedbindingsdemo extends 

graphics2dactivity{     
          
@Inject ishape  shape;     
          
protected void DrawImage () {     
          
/**    
* semi-opaque blue color in    
* The ARGB spaces (Alpha is 0x78)/ 
Co Lor Bluecolor = new Color (0x780000ff,true);     
/**    
* The semi-opaque yellow color in the    
* ARGB spaces (alpha is 0x78)    
/ 
Color yellowcolor = new Col or (0x78ffff00,true);     
          
/**    
* The dash array    
* 
/int dasharray[] = {8};     
Graphics2d.clear (color.white);     
Graphics2d.reset ();     
Pen pen=new Pen (Yellowcolor,10,pen.cap_butt,     
pen.join_miter,dasharray,0);     
SolidBrush brush=new SolidBrush (bluecolor);     
Graphics2d.setpenandbrush (Pen,brush);     
Graphics2d.fill (null,shape);     
Graphics2d.draw (Null,shape);     
          
}