PPT Slide

Objects and References

Box shoeBox

= new Box();

Box cdBox

= new Box();

Box present

= new Box();

The data fields (“attributes”):

int iLength;

int iWidth;

int iHeight;

What can be done to that data(“methods”):

public void setLength (int iNewLength)

public int getLength ( )

public void setWidth (int iNewWidth)

public int getWidth ( )

public void setHeight (int iNewHeight)

public int getHeight ( )

public int getVolume ( )

shoeBox

The data fields (“attributes”):

int iLength;

int iWidth;

int iHeight;

What can be done to that data(“methods”):

public void setLength (int iNewLength)

public int getLength ( )

public void setWidth (int iNewWidth)

public int getWidth ( )

public void setHeight (int iNewHeight)

public int getHeight ( )

public int getVolume ( )

cdBox

The data fields (“attributes”):

int iLength;

int iWidth;

int iHeight;

What can be done to that data(“methods”):

public void setLength (int iNewLength)

public int getLength ( )

public void setWidth (int iNewWidth)

public int getWidth ( )

. . .

present

Each time we instantiate

a Box, therefore, we get a unique copy to work with. This is one of the most powerful aspect of Object-Oriented Programming!

David Dagon:

(Cautionary Note: Here, we suggest that each object gets a unique copy of each method. Although each object is allocated unique memory space for variables, Java efficiently shares methods in common with all objects. For now, you might find it helpful to picture objects in the manner, even though it’s not technically what happens with the heap’s method space in the Java Virtual Machine.)

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