classes and methods...


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  1. #1
    Join Date
    Oct 2003
    Posts
    2

    classes and methods...

    i am having a bit of trouble making this work
    Code:
    import java.awt.*;
    import java.applet.Applet;
    
    public class transport extends Applet{
    
    skateboard Skateboard1;
    skateboard Skateboard2;
    motorbike Motorbike1;
    bike Bicycle1;
    bike Bicycle2;
    car Car1;
    car Car2;
    
    public void init(){
    		this.setLayout(new Gridlayout(7.1));
    		Skateboard1=new skateboard();
    		add(Skateboard1);
    		Skateboard2=new skateboard();
    		add(Skateboard2);
    		Motorbike1=new motorbike();
    		add(Motorbike1);
    		Bicycle1=new bike();
    		add(Bicycle1);
    		Bicycle2=new bike();
    		add(Bicycle2);
    		Car1=new car();
    		add(Car1);
    		Car2=new car();
    		add(Car2);
    }
    
    public class vehicle extends Panel{//vehicle class, main class
    	
    	Label make=new Label();
    	Label model=new Label();
    	Label colour=new Label();
    	Label cost=new Label();
    	Label length=new Label();
    	
    	public class motorbike extends vehicle{// Motorbike class
    			
    			Label engine=new Label();
    			Label fuel=new Label();
    			Label height=new Label();
    			Label regno=new Label();
    			Label acceleration=new Label();
    			
    			motorbike(){
    				super();
    				make.setText("Make is: UNKNOWN");
    				model.setText("Model is: UNKNOWN");
    				colour.setText("colour is: UNKNOWN");
    				cost.setText("cost is: UNKNOWN");
    				length.setText("length is: UNKNOWN");
    				engine.setText("engine is: UNKNOWN");
    				fuel.setText("fuel is: UNKNOWN");
    				height.setText("height is: UNKNOWN");
    				regno.setText("reistration is: UNKNOWN");
    				acceleration.setText("acceleration is: UNKNOWN");
    				
    				add(make);
    				add(model);
    				add(colour);
    				add(cost);
    				add(length);
    				add(engine);
    				add(fuel);
    				add(height);
    				add(regno);
    				add(acceleration);
    			}
    		public class car extends motorbike{// Car class, Subclass of motorbike
    		  	Label passengers=new Label();
    			car(){
    				super();
    				passengers.setText("Number of passengers is: UNKNOWN");
    				add(passengers);
    			}
    		}
    			}
    	
    
    	public class unpowered extends vehicle{//unpowered class
    		Label weight=new Label();
    		unpowered(){
    			super();
    			weight.setText("Weight is: UNKNOWN");
    			add(weight);
    		}
    		
    		public class skateboard extends unpowered{//skateboard class, subclass of unpowered
    			Label width=new Label();
    			skateboard(){
    				super();
    				width.setText("Width is: UNKNOWN");
    				add(width);
    			}
    		}
    		public class bike extends unpowered{//bike class, subclass of unpowered
    			Label gears=new Label();
    			bike(){
    				super();
    				gears.setText("The number of gears is: UNKNOWN");
    				add(gears);
    			}
    		}
    	}
    
    }
    }
    i cant seem to fix the errors, maily about the super(); bits, and the beginning variables. what have i done wrong?

  2. #2
    Join Date
    Mar 2003
    Posts
    834
    Please post any error messages you're getting.
    ArchAngel.
    O:-)

  3. #3
    Join Date
    Oct 2003
    Posts
    2
    javac transport.java
    transport.java:6: cannot resolve symbol
    symbol : class skateboard
    location: class transport
    skateboard Skateboard1;
    ^
    transport.java:7: cannot resolve symbol
    symbol : class skateboard
    location: class transport
    skateboard Skateboard2;
    ^
    transport.java:8: cannot resolve symbol
    symbol : class motorbike
    location: class transport
    motorbike Motorbike1;
    ^
    transport.java:9: cannot resolve symbol
    symbol : class bike
    location: class transport
    bike Bicycle1;
    ^
    transport.java:10: cannot resolve symbol
    symbol : class bike
    location: class transport
    bike Bicycle2;
    ^
    transport.java:11: cannot resolve symbol
    symbol : class car
    location: class transport
    car Car1;
    ^
    transport.java:12: cannot resolve symbol
    symbol : class car
    location: class transport
    car Car2;
    ^
    transport.java:15: cannot resolve symbol
    symbol : class Gridlayout
    location: class transport
    this.setLayout(new Gridlayout(7.1));
    ^
    transport.java:16: cannot resolve symbol
    symbol : class skateboard
    location: class transport
    Skateboard1=new skateboard();
    ^
    transport.java:18: cannot resolve symbol
    symbol : class skateboard
    location: class transport
    Skateboard2=new skateboard();
    ^
    transport.java:20: cannot resolve symbol
    symbol : class motorbike
    location: class transport
    Motorbike1=new motorbike();
    ^
    transport.java:22: cannot resolve symbol
    symbol : class bike
    location: class transport
    Bicycle1=new bike();
    ^
    transport.java:24: cannot resolve symbol
    symbol : class bike
    location: class transport
    Bicycle2=new bike();
    ^
    transport.java:26: cannot resolve symbol
    symbol : class car
    location: class transport
    Car1=new car();
    ^
    transport.java:28: cannot resolve symbol
    symbol : class car
    location: class transport
    Car2=new car();
    ^
    transport.java:75: cannot reference this before supertype constructor has been called
    super();
    ^
    transport.java:94: cannot reference this before supertype constructor has been called
    super();
    ^
    transport.java:102: cannot reference this before supertype constructor has been called
    super();
    ^
    18 errors

    not really sure how to fix them.. pardon if i am a n00b...

  4. #4
    Join Date
    Mar 2003
    Posts
    834
    Well, it's clear from the error message that it can't find skateboard (by the way, classes in Java typically have a first capital letter - Skateboard).

    You've written your hierarchy in a very strange way, using nested classes. Why? Is it some form of requirement?

    If you want to leave it like that, then you'll have to create instances of other classes before you can reach a class from which skateboard is visible.
    ArchAngel.
    O:-)

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