Assume the existence of an interface, CommDevice, with the following methods: tr

Question

Assume the existence of an interface, CommDevice, with the

following methods:

transmit: accepts two string parameters and returns nothing

receive: accepts two string parameters and returns a

boolean

Define a class, Firewall, that implements the above interface,

and has the following members:

a string instance variable, permittedReceiver

a string instance variable, buffer

a constructor that accepts a string parameter that is used to

initialize the permittedReceiver variable

an implementation of the transmit method that assigns the first

parameter to the destination instance variable and the second to

the buffer variable. It also send to System.out the message "Data

scheduled for transmission to dest" where dest is replaced by the

actual value of the destination string.

an implementation of the receiver method that checks if the

first parameter is equal to the permittedReceiver and if so it sets

the buffer instance variable to the second parameter and returns

true; otherwise it sets the buffer to the empty string, prints the

message "Attempted breach of firewall by " where is replaced by the

method's first parameter, and returns false.

Explanation / Answer

public interface CommDevice {
public void transmit(String str1, String str2);
public boolean receive(String str1, String str2);
}

public class Firewall implements CommDevice {

private String permittedReceiver;
private String buffer;
private String destination;

public Firewall(String permittedReceiver) {
super();
this.permittedReceiver = permittedReceiver;
}

@Override
public void transmit(String str1, String str2) {
str1 = destination;
str2 = buffer;
System.out.println("Data scheduled for transmission to " + destination);
}

@Override
public boolean receive(String str1, String str2) {
if(str1.equals(permittedReceiver)) {
str2 = buffer;
return true;
}
else {
buffer = "";
System.out.println("Attempted breach of firewall by " + str1);
return false;
}

}

}

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