title: invoke error EditText() null object reference
body: <p>I know this maybe a very simple solution but I can't for the life of me get this part of the code working for my symptom checker. Everything else is working flawlessly but the application completely crashes at the diagnosis part method.</p>
  
  <p>Here is part of the java file causing the problem (question activity):</p>
  
  <pre><code>public class Questions extends AppCompatActivity {
  
  private Button button2;
  
  private RadioButton radioButton;
  private RadioButton radioButton2;
  private RadioButton radioButton3;
  private RadioButton radioButton4;
  private RadioButton radioButton5;
  private RadioButton radioButton6;
  private RadioButton radioButton7;
  private RadioButton radioButton8;
  private RadioButton radioButton9;
  private RadioButton radioButton10;
  private RadioButton radioButton11;
  private RadioButton radioButton12;
  private RadioButton radioButton13;
  private RadioButton radioButton14;
  private RadioButton radioButton15;
  private RadioButton radioButton16;
  private RadioButton radioButton17;
  private RadioButton radioButton18;
  
  
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_questions);
  
  
      button2 = findViewById(R.id.button2);
      button2.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
              opendiagnosis();
              diagnosispart();
          }
      });
  
      //Question 1
      radioButton = findViewById(R.id.radioButton); //yes
      radioButton2 = findViewById(R.id.radioButton20); //no
      //Question 2
      radioButton3 = findViewById(R.id.radioButton4); //yes
      radioButton4 = findViewById(R.id.radioButton2); //no
      //Question 3
      radioButton5 = findViewById(R.id.radioButton6); //yes
      radioButton6 = findViewById(R.id.radioButton5); //no
      //Question 4
      radioButton7 = findViewById(R.id.radioButton7); //yes
      radioButton8 = findViewById(R.id.radioButton8); //no
      //Question 5
      radioButton9 = findViewById(R.id.radioButton9); //yes
      radioButton10 = findViewById(R.id.radioButton10); //no
      //Question 6
      radioButton11 = findViewById(R.id.radioButton12); //yes
      radioButton12 = findViewById(R.id.radioButton11); //no
      //Question 7
      radioButton13 = findViewById(R.id.radioButton13); //yes
      radioButton14 = findViewById(R.id.radioButton14); //no
      //Question 8
      radioButton15 = findViewById(R.id.radioButton15); //yes
      radioButton16 = findViewById(R.id.radioButton16); //no
      //Question 9
      radioButton17 = findViewById(R.id.radioButton17); //yes
      radioButton18 = findViewById(R.id.radioButton18); //no
  }
  
  
  public void opendiagnosis() {
      // for all pairs: one of each pair has to be checked
      boolean shouldStartNextActivity = (radioButton.isChecked() || radioButton2.isChecked())
              &amp;&amp; (radioButton3.isChecked() || radioButton4.isChecked()) &amp;&amp; (radioButton5.isChecked() || radioButton6.isChecked())
              &amp;&amp; (radioButton7.isChecked() || radioButton8.isChecked())&amp;&amp; (radioButton9.isChecked() || radioButton10.isChecked())
              &amp;&amp; (radioButton11.isChecked() || radioButton12.isChecked())&amp;&amp; (radioButton13.isChecked() || radioButton14.isChecked())
              &amp;&amp; (radioButton15.isChecked() || radioButton16.isChecked())&amp;&amp; (radioButton17.isChecked() || radioButton18.isChecked());
  
  
      if (shouldStartNextActivity){
          Intent intent = new Intent(this, answers.class);
          startActivity(intent);
      } else{
          Toast.makeText(getBaseContext(), "Please answer all the questions for an accurate diagnosis", Toast.LENGTH_LONG).show();
      }
  }
  
  public void diagnosispart() {
      EditText text = (findViewById(R.id.textView16));
  
      String value = text.getText().toString();
  
      Intent i = new Intent(this, answers.class);
      i.putExtra("Value1", "this is it");
      startActivity(i);
  
  }
  
  @Override
  public void onSaveInstanceState(Bundle savedInstanceState) {
      super.onSaveInstanceState(savedInstanceState);
  
  
      savedInstanceState.putBoolean("myOption1", radioButton.isChecked());
      savedInstanceState.putBoolean("myOption2", radioButton2.isChecked());
      savedInstanceState.putBoolean("myOption3", radioButton3.isChecked());
      savedInstanceState.putBoolean("myOption4", radioButton4.isChecked());
      savedInstanceState.putBoolean("myOption5", radioButton5.isChecked());
      savedInstanceState.putBoolean("myOption6", radioButton6.isChecked());
      savedInstanceState.putBoolean("myOption7", radioButton7.isChecked());
      savedInstanceState.putBoolean("myOption8", radioButton8.isChecked());
      savedInstanceState.putBoolean("myOption9", radioButton9.isChecked());
      savedInstanceState.putBoolean("myOption10", radioButton10.isChecked());
      savedInstanceState.putBoolean("myOption11", radioButton11.isChecked());
      savedInstanceState.putBoolean("myOption12", radioButton12.isChecked());
  }
  
  @Override
  public void onRestoreInstanceState(Bundle savedInstanceState) {
      super.onRestoreInstanceState(savedInstanceState);
  
      radioButton.setChecked(savedInstanceState.getBoolean("myOption1"));
      radioButton2.setChecked(savedInstanceState.getBoolean("myOption2"));
      radioButton3.setChecked(savedInstanceState.getBoolean("myOption3"));
      radioButton4.setChecked(savedInstanceState.getBoolean("myOption4"));
      radioButton5.setChecked(savedInstanceState.getBoolean("myOption5"));
      radioButton6.setChecked(savedInstanceState.getBoolean("myOption6"));
      radioButton7.setChecked(savedInstanceState.getBoolean("myOption7"));
      radioButton8.setChecked(savedInstanceState.getBoolean("myOption8"));
      radioButton9.setChecked(savedInstanceState.getBoolean("myOption9"));
      radioButton10.setChecked(savedInstanceState.getBoolean("myOption10"));
      radioButton11.setChecked(savedInstanceState.getBoolean("myOption11"));
      radioButton12.setChecked(savedInstanceState.getBoolean("myOption12"));
  
  }
  }
  </code></pre>
  
  <p>The intent is then passed to the answers activity where its meant to display in textView16:</p>
  
  <pre><code> public class answers extends AppCompatActivity {
  
   private Button button7;
  
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_answers);
  
      Bundle extras = getIntent().getExtras();
      if (extras == null) {
          return;
      }
  
      String value1 = extras.getString("Value1");
      if (value1 != null) {
  
          TextView displayintentextra = findViewById(R.id.textView16);
          displayintentextra.setText(value1);
      }
  
      button7 = findViewById(R.id.button7);
      button7.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
              reset();
          }
      });
  
  }
  
  
  public void reset() {
      Intent intent = new Intent(this, Questions.class);
      startActivity(intent);
  }
  
  }
  </code></pre>
  
  <p>Here is what the logcat says:</p>
  
  <pre><code>2020-01-30 08:07:37.581 20275-20275/com.example.mhtapplication E/AndroidRuntime: FATAL EXCEPTION: main
  Process: com.example.mhtapplication, PID: 20275
  java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference
      at com.example.mhtapplication.Questions.onlick(Questions.java:103)
  </code></pre>
  
  <p>XML file where the edittext view is based:</p>
  
  <pre><code>&lt;EditText
  android:id="@+id/textView16"
  android:layout_width="384dp"
  android:layout_height="wrap_content"
  android:layout_marginStart="8dp"
  android:layout_marginLeft="8dp"
  android:layout_marginTop="12dp"
  android:text=""
  app:layout_constraintStart_toStartOf="parent"
  app:layout_constraintTop_toBottomOf="@+id/textView13" /&gt;
  </code></pre>