This method will be used to match a robot\'s current state and sensor readings a

Question

This method will be used to match a robot's current state and sensor readings against a program statement to see if they are a match. The parameters n/e/w/s will each be true if there is a wall in the immediately adjacent square. If state does not match "the trigger state" return false. If n is true and the first character of the trigger sensors is x, or n is false and the first character of the trigger sensors is n, return false. The remaining parameters should behave similarly to n except with the second, third and fourth characters of the trigger sensors. If none of these tests causes the method to return false, then true should be returned.

Explanation / Answer

I have answered this question earlier and I think this is for SimpleBotStatement.

Given below is the code for the class SimpleBotStatement. Hope the answer helped. If it did, please don't forget to rate it. Thank you.

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public class SimpleBotStatement {
private int state;
private String sensors;
private int nextState;
private char action;
public SimpleBotStatement(String s)
{
String[] tokens = s.split("(\s)+"); //split tokens using 1 or more whitespaces
try{
state = Integer.parseInt(tokens[0]);
sensors = tokens[1];
checkSensors(); //call the private method to check if the trigger sensors are valid
if(!tokens[2].equals("->"))
throw new IllegalArgumentException("Expected -> after trigger sensors . Found " + tokens[2]);
//next token should be single char action, check if its valid value
String validAction = "newsx";
if(tokens[3].length() != 1 || validAction.indexOf(tokens[3]) == -1 )
throw new IllegalArgumentException("Action should be a single character and one of n/e/w/s/x");
action = tokens[3].charAt(0);
nextState = Integer.parseInt(tokens[4]);
}catch(Exception e)
{
throw new IllegalArgumentException(e.getMessage());
}
}
public boolean match(int state, boolean n, boolean e, boolean w, boolean s)
{
if(this.state != state)
return false;
char ch = sensors.charAt(0);
if((n == true && ch == 'x' ) || (n == false && ch =='n'))
return false;
ch = sensors.charAt(1);
if((e == true && ch == 'x' ) || (e == false && ch =='e'))
return false;
ch = sensors.charAt(2);
if((w == true && ch == 'x' ) || (w == false && ch =='w'))
return false;
ch = sensors.charAt(3);
if((n == true && ch == 'x' ) || (s == false && ch =='s'))
return false;
return true;
}
public int nextState()
{
return nextState;
}
public char nextAction()
{
return action;
}
private void checkSensors()
{
boolean valid = true;
String err = "";
if(sensors.length() == 4)
{
String[] allowed = {"nx*", "ex*", "wx*", "sx*"}; //allowed characters for each of character positions
//if position is 0, then only n, x * are allowed
//if position is 1, then only e, x and * are allowed and so on
//now check if each character has valid character according to its position
for(int pos = 0; valid && pos < sensors.length(); pos++)
{
char ch = sensors.charAt(pos);
if(allowed[pos].indexOf(ch) == -1)
{
err = "Trigger Sensors invalid. Expected one of the characters in " + allowed[pos]+" at index "
+ pos + ". Found "+ ch;
valid = false;
}
}
}
else
{
err = "Trigger sensors be only 4 characters long";
valid = false;
}
if(!valid)
throw new IllegalArgumentException(err);
}
}

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