LunarLander

java.lang.Object
- LunarLander

```
class LunarLander
extends Object
```
LunarLander keeps track of the current state of the lunar lander, namely the lander's current altitude, speed and fuel.

It is to be assumed that the lander's data is updated once every second.

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`GRAVITY` The gravitational constant for the moon (in meters/second/second)
`static int`	`INITIAL_ALTITUDE` The initial altitude of the lander (in meters)
`static int`	`INITIAL_FUEL` The initial amount of fuel (number of thrusts) available to the lander
`static int`	`INITIAL_VELOCITY` The initial velocity of the lander (in meters/second)
`static int`	`SAFE_LANDING` The maximum speed at which the lander can safely land (in meters/second)
`static int`	`THRUST` The thrust acceleration generated by consuming one unit of fuel (in meters/second/second)

Constructor Summary

Constructors
Constructor and Description

LunarLander()
Constructs a new LunarLander in the initial (default) configuration.

Constructors
Constructor and Description
`LunarLander()` Constructs a new LunarLander in the initial (default) configuration.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`int`	`getAltitude()` The current altitude of the lander (in meters).
`int`	`getFuel()` The current amount of fuel remaining.
`int`	`getVelocity()` The current velocity of the lander (in meters/second).
`void`	`reset()` Restores the Lander to its initial (default) configuration.
`void`	`thrust()` Request one unit of fuel be burned to generate upward thrust.
`void`	`tick()` Updates state of lander based on current velocity, thrust requests since the last update, altitude, and remaining fuel available.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - INITIAL_VELOCITY
```
public static final int INITIAL_VELOCITY
```
    The initial velocity of the lander (in meters/second)
    
    See Also:
    
    Constant Field Values
  - INITIAL_ALTITUDE
```
public static final int INITIAL_ALTITUDE
```
    The initial altitude of the lander (in meters)
    
    See Also:
    
    Constant Field Values
  - INITIAL_FUEL
```
public static final int INITIAL_FUEL
```
    The initial amount of fuel (number of thrusts) available to the lander
    
    See Also:
    
    Constant Field Values
  - GRAVITY
```
public static final int GRAVITY
```
    The gravitational constant for the moon (in meters/second/second)
    
    See Also:
    
    Constant Field Values
  - THRUST
```
public static final int THRUST
```
    The thrust acceleration generated by consuming one unit of fuel (in meters/second/second)
    
    See Also:
    
    Constant Field Values
  - SAFE_LANDING
```
public static final int SAFE_LANDING
```
    The maximum speed at which the lander can safely land (in meters/second)
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - LunarLander
```
public LunarLander()
```
    Constructs a new LunarLander in the initial (default) configuration.
- Method Detail
  - reset
```
public void reset()
```
    Restores the Lander to its initial (default) configuration.
  - getAltitude
```
public int getAltitude()
```
    The current altitude of the lander (in meters).
  - getVelocity
```
public int getVelocity()
```
    The current velocity of the lander (in meters/second).
  - getFuel
```
public int getFuel()
```
    The current amount of fuel remaining. Each thrust request consumes one unit of fuel.
    
    ensures: this.getFuel() >= 0
  - thrust
```
public void thrust()
```
    Request one unit of fuel be burned to generate upward thrust. More than one unit can be burned each second (between updates).
  - tick
```
public void tick()
```
    Updates state of lander based on current velocity, thrust requests since the last update, altitude, and remaining fuel available.
    
        ensures:
                   this.getVelocity() == old.getVelocity() - GRAVITY + THRUST * (the number of valid thrust requests since the last update) AND
                   this.getAltitude() == old.getAltitude() - this.getVelocity() AND
                   this.getFuel() >= 0 AND this.getFuel() == old.getFuel() - (the number of valid thrust requests since the last update)

Class LunarLander

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

INITIAL_VELOCITY

INITIAL_ALTITUDE

INITIAL_FUEL

GRAVITY

THRUST

SAFE_LANDING

Constructor Detail

LunarLander

Method Detail

reset

getAltitude

getVelocity

getFuel

thrust

tick