cannot find symbol Error

Can someone help me with debugging this error?
This is the error Im getting but I do not know why.

SharedBufferTest.java:16: cannot find symbol
symbol : constructor Producer(Buffer)
location: class Producer
Producer producer = new Producer( sharedLocation );
^
SharedBufferTest.java:17: cannot find symbol
symbol : constructor Consumer(Buffer)
location: class Consumer
Consumer consumer = new Consumer( sharedLocation );

Here is the code for SharedBufferTest.java

Code :

---

public class SharedBufferTest {
	public static void main( String [] args)
	{
 
	Buffer sharedLocation = new UnsynchronizedBuffer();
 
 
	Producer producer = new Producer( sharedLocation );
	Consumer consumer = new Consumer( sharedLocation );
	Semaphore valueProduced=new Semaphore(0);
	Semaphore valueConsumed = new Semaphore(1);
 
		producer.start();
		consumer.start();
 
	}
}

---

Here is the Producer code

Code :

---

public class Producer extends Thread{
	private Buffer sharedLocation;
	private Semaphore valueProduced;
	private Semaphore valueConsumed;
 
	public Producer (Buffer shared, Semaphore valueP, Semaphore valueC) {
		super("Producer");
		sharedLocation = shared;
		valueProduced = valueP;
		valueConsumed = valueC;
	}
 
	public void run() {
		for (int count = 1; count <= 4; count++){
			//try {
				//Thread.sleep((int) (Math.random() * 3001));
				valueConsumed.P();
				//check to see if the value has been consumed P( valueConsumed );
				sharedLocation.set(count);
				//let consumer thread know it can consume the value
				valueProduced.V();
			//}
			//catch (InterruptedException exception) {
				//exception.printStackTrace();
			//}
		}
		System.err.println(getName() + " done producing.");
	}
}

---

Here is the Consumer code

Code :

---

public class Consumer extends Thread{
	private Buffer sharedLocation;
	private Semaphore valueProduced;
	private Semaphore valueConsumed;
 
	public Consumer (Buffer shared, Semaphore valueP, Semaphore valueC) {
		super("Consumer");
		sharedLocation = shared;
		valueProduced = valueP;
		valueConsumed = valueC;
 
	}
	public void run() {
		int sum = 0;
		for (int count=1; count<=4; count++) {
			//try{
				//how it shouldve worked:
				//sharedLocation.get()=null; check to see if the buffer is empty
				//if 
				//Thread.sleep((int) (Math.random() * 3001));
				valueProduced.P();
				sum += sharedLocation.get();
				valueConsumed.V();
			//}
			//catch (InterruptedException exception) {
				//exception.printStackTrace();
			//}
		}
		System.err.println(getName() + " done consuming. and sum= " + sum);
	}
}

---

So I recompiled the program again and now Im getting these errors:

cannot find symbol
symbol : class Buffer
location: class SharedBufferTest
Buffer sharedLocation = new UnsynchronizedBuffer();
^
./UnsynchronizedBuffer.java:9: cannot find symbol
symbol: class Buffer
public class UnsynchronizedBuffer implements Buffer {
^
./Producer.java:10: cannot find symbol
symbol : class Buffer
location: class Producer
private Buffer sharedLocation;
^
./Producer.java:14: cannot find symbol
symbol : class Buffer
location: class Producer
public Producer (Buffer shared, Semaphore valueP, Semaphore valueC) {
^
SharedBufferTest.java:16: internal error; cannot instantiate Producer.<init> at Producer to ()
Producer producer = new Producer( sharedLocation );
^
./Consumer.java:10: cannot find symbol
symbol : class Buffer
location: class Consumer
private Buffer sharedLocation;
^
./Consumer.java:14: cannot find symbol
symbol : class Buffer
location: class Consumer
public Consumer (Buffer shared, Semaphore valueP, Semaphore valueC) {
^
SharedBufferTest.java:17: internal error; cannot instantiate Consumer.<init> at Consumer to ()
Consumer consumer = new Consumer( sharedLocation );
^
./Consumer.java:30: inconvertible types
found : <nulltype>
required: int
sum += sharedLocation.get();

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New To Java - cannot find symbol

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