Simple app is crashing I am just traying to change the visibility of some views

Question

public class MainActivity extends AppCompatActivity {

Button b1= (Button) findViewById(R.id.button);
TextView tvl=(TextView)findViewById(R.id.textView2);

 

    public void clickGo(View view)
        {
            b1.setVisibility(View.INVISIBLE);
            tvl.setVisibility(View.VISIBLE);
        }
   

     @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
        
        
            }
        }

I am trying to disappear the button and allow text to be visible this is code I am not able to find why it is crashing please help.

Answer 1

The reason your app is crashing it's because your'e trying to setVisibility something that is null becasue the way you initialized your views is not correct, and you need you do it like this. Without a constructor.

public class MainActivity extends AppCompatActivity {

Button b1;
TextView tvl;

       @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);

         b1 = findViewById(R.id.button);
         tvl = findViewById(R.id.text);
         b1.setVisibility(View.INVISIBLE);
         tvl.setVisibility(View.VISIBLE);
    }
}

Answer 2

lets try this bro

public class MainActivity extends AppCompatActivity {
        
    
             @Override
                protected void onCreate(Bundle savedInstanceState) {
                    super.onCreate(savedInstanceState);
                    setContentView(R.layout.activity_main);
                  Button b1= (Button) findViewById(R.id.button);
                 TextView tvl=(TextView)findViewById(R.id.textView2);
                b1.setOnClickListener(v -> {

                b1.setVisibility(View.INVISIBLE);
                tvl.setVisibility(View.VISIBLE);
                   
               }           
          }
       }