title: I tried to write code in startActivity.java, but showing error while build
body: <pre><code>private Button mRegBtn;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_start);
  
      mRegBtn =(Button)findViewById(R.id.start _reg_btn);
      mRegBtn.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
              Intent reg_intent = new Intent(StartActivity.this, RegisterActivity.class);
               startActivity(reg_intent);
  
          }
      });
  
  
  
      }
  </code></pre>
  
  <p>This one showing in red color and failed to find "start _reg_btn"</p>
  
  <p>and showing like below</p>
  
  <pre><code>null    
  G:/HELLOWORLD   
  app/src/main/java   
  com/example/helloworld/StartActivity.java   
  error: ')' expected 
  error: illegal start of expression  
  </code></pre>