I'm sure it's clear to you but remember that we know nothing about your project other than what you tell us.
However, in general terms:
1. Pass a reference of one class' object to the other class' object through the constructor or setter from the first or a getter in the second,
2. Use the reference of the first class' object to obtain data through getters in the first class.
I created a simple demo to show how this can be done using one of the approaches described above:
// a simple class to pass an instance of itself to a second class. the second
// class will then send a value to the first
public class TestClass
{
SecondClass secondClass;
int value;
// default constructor
public TestClass()
{
new SecondClass( this );
} // end default constructor
// method setValue() sets value to the argument int
public void setValue( int value )
{
this.value = value;
} // end method setValue()
// method main() to
public static void main(String args[])
{
new TestClass();
} // end method main()
} // end class TestClass
// accepts an reference to an instance of the first class and uses that
// reference to pass a value back to the first
class SecondClass
{
TestClass testClass;
// a constructor that accepts a reference to the first class as
// a parameter
public SecondClass( TestClass testClass )
{
this.testClass = testClass;
// sets the value of a field in the first class
// ('this.' is unnecessary here in the constructor but is
// used for clarity.)
this.testClass.setValue( 5 );
} // end constructor
} // end class SecondClass