Hi there, Thanks to all those who read and tried to help me. I have finally solved the problem.

All I had to do was to place setOnItemSelectedListener for the first two spinners within the onCreate then use functions to populate the second and third spinner based on the selection. Note: the first spinner is populate from the string xml file.

Below is the sample code
inside onCreate:

     //set onItemSelected Listener
        spinProvince.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                String province = (String)parent.getItemAtPosition(position);

                if(province.matches("Eastern Cape")){
                    spinPro = 1;
                    populateDist();
                }
                else if(province.matches("Free State")){
                    spinPro = 2;
                    populateDist();
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
                Toast.makeText(Reg_Prop.this, "Please select the Province where the Property is located", Toast.LENGTH_LONG).show();

            }
        });

        spinDistrict.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener(){

            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                String spinDist = (String)parent.getItemAtPosition(position);

                if(spinDist.matches("Buffalo City") && spinPro == 1){
                    dist = 1;
                    populateLocal();
                }
                else if(spinDist.matches("Nelson Mandela Bay") && spinPro == 1){
                    dist = 2;
                    populateLocal();
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });

Functions to populate the spinners

    void populateDist(){
        //Eatern Cape
        if(spinPro == 1){
            String [] ec = {"Select District/Metro *", "Buffalo City", "Nelson Mandela Bay",
                    "Alfred Nzo District", "Amathole District", "Chris Hani District",
                    "Joe Gqabi District", "OR Tambo District", "Cacadu District"};

            ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, ec);
            spinDistrict.setAdapter(adapter);
        }
        //Free State
        else if(spinPro == 2){
            String [] fs = {"Select District/Metro *", "Mangaung Metropolitan", "Fezile Dabi District",
                    "Lejweleputswa District", "Thabo Mofutsanyana District", "Xhariep District"};

            ArrayAdapter<String> adapter2 = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, fs);
            spinDistrict.setAdapter(adapter2);
        }

    }

    void populateLocal(){
        //Baffalo City
        if(dist == 1){
            String [] bc = {"Buffalo City"};

            ArrayAdapter<String> adapterL1 = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, bc);
            spinLocal.setAdapter(adapterL1);
        }
        //Nelson Mandela Bay
        else if(dist == 2){
            String [] nmb = {"Nelson Mandela Bay"};

            ArrayAdapter<String> adapterL2 = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, nmb);
            spinLocal.setAdapter(adapterL2);
        }

    }