The app is crashing due to null-pointer-exception

Question

The app is crashing as soon as I open it. It says its a null pointer exception.

This is what the logcat shows:

 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void

android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.titanic_survival_prediction.MainActivity.onCreate(MainActivity.java:48)

Here is the full code:

public class MainActivity extends AppCompatActivity {
    
        EditText age, sex, pclass, embarked, fare, sibsp, parch;
    
        Button predict;
        TextView result;
        String url = "https://titanic-android-app.herokuapp.com/predict";
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            age = findViewById(R.id.age);
            sex = findViewById(R.id.sex);
            pclass = findViewById(R.id.pclass);
            embarked = findViewById(R.id.embarked);
            fare = findViewById(R.id.fare);
            sibsp = findViewById(R.id.sibsp);
            parch = findViewById(R.id.parch);
    
            result = findViewById(R.id.result);
    
            predict.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    // Hit the API
                    StringRequest stringRequest = new StringRequest(Request.Method.POST, url,
                            new Response.Listener<String>() {
                                @Override
                                public void onResponse(String response) {
                                    try {
                                        JSONObject jsonObject = new JSONObject(response);
                                        String data = jsonObject.getString("Survived");
    
                                        if (data.equals("1")){
                                            result.setText("You Survived");
                                        }
                                        else{
                                            result.setText("You Died");
                                        }
                                    } catch (JSONException e) {
                                        e.printStackTrace();
                                    }
    
                                }
                            },
                            new Response.ErrorListener() {
                                @Override
                                public void onErrorResponse(VolleyError error) {
                                    Toast.makeText(MainActivity.this, error.getMessage(), Toast.LENGTH_SHORT).show();
                                }
                            }){
                        @Override
                        protected Map<String,String> getParams(){
                            Map<String, String> params = new HashMap<String, String>();
                            params.put("Age_band", age.getText().toString());
                            params.put("Sex", sex.getText().toString());
                            params.put("Pclass", pclass.getText().toString());
                            params.put("Embarked", embarked.getText().toString());
                            params.put("Fare_cat", fare.getText().toString());
                            params.put("Sibsp", sibsp.getText().toString());
                            params.put("Parch", parch.getText().toString());
    
                            return params;
                        }
                    };
                    RequestQueue queue = Volley.newRequestQueue(MainActivity.this);
                    queue.add(stringRequest);
                }
            });
        }
    }

This is the part where its logcat shows null pointer exception:

predict.setOnClickListener(new View.OnClickListener() {

There is no problem with the xml file. This app uses an ML model which I made and deployed on heroku.