该应用程序的开始是通过使布局中的每一个其他的东西是不可行的或消失了（我不知道哪一个它应该-请推荐）。我已经做了按钮，它和其他每一个视图，但一旦我点击按钮，我的应用程序崩溃。这里是所有的java。

package com.example.braintimer;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.GridLayout;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    GridLayout game;

    TextView timer;

    TextView problem;

    TextView result;
    TextView score;
    Button newGame;

    public void firstGo(View view) {
        Button firstGo = (Button) findViewById(R.id.firstGo);

       game  = (GridLayout) findViewById(R.id.gridLayout);

       timer  = (TextView) findViewById(R.id.timer);

       problem = (TextView) findViewById(R.id.problem);

       result  = (TextView) findViewById(R.id.result);

       score  = (TextView) findViewById(R.id.score);

       newGame  = (Button) findViewById(R.id.newGame);

        firstGo.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.i("1" , "Didnt crash");
                firstGo.setVisibility(View.GONE);

                game.setVisibility(View.VISIBLE);
                timer.setVisibility(View.VISIBLE);
                problem.setVisibility(View.VISIBLE);
                result.setVisibility(View.VISIBLE);
                score.setVisibility(View.VISIBLE);
                newGame.setVisibility(View.VISIBLE);
            }
        });
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}``` 
Please recommend what should be done to stop the app crashing. Also can anyone tell that how should I get the math questions i want for the app
Thank you