Program: 78186
Project: 78186
Buggy source:
@Override public void onCreate(@Nullable Bundle savedInstanceState){
  super.onCreate(savedInstanceState);
  setContentView(R.layout.intro_view);
  findViewById(R.id.btn_login).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View view){
      switchView();
    }
  }
);
  findViewById(R.id.btn_back).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View view){
      switchView();
    }
  }
);
  findViewById(R.id.btn_scan).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View view){
      Intent i=new Intent(IntroViewActivity.this,QRview.class);
      i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
      i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
      startActivity(i);
    }
  }
);
  findViewById(R.id.btn_create).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View view){
      Snackbar mySnackbar=Snackbar.make(findViewById(R.id.introtop),"String_Node_Str",Snackbar.LENGTH_SHORT);
      mySnackbar.show();
    }
  }
);
  findViewById(R.id.btn_createNOW).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View view){
      EditText address=findViewById(R.id.address_text);
      EditText publickey=findViewById(R.id.public_text);
      EditText privatekey=findViewById(R.id.private_text);
      saveString("String_Node_Str",address.getText().toString());
      saveString("String_Node_Str",publickey.getText().toString());
      saveString("String_Node_Str",privatekey.getText().toString());
      Intent i=new Intent(IntroViewActivity.this,MainActivity.class);
      i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
      i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
      startActivity(i);
    }
  }
);
}

Fixed version (ground truth):
@Override public void onCreate(@Nullable Bundle savedInstanceState){
  super.onCreate(savedInstanceState);
  setContentView(R.layout.intro_view);
  findViewById(R.id.btn_login).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View view){
      switchView();
    }
  }
);
  findViewById(R.id.btn_back).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View view){
      switchView();
    }
  }
);
  findViewById(R.id.btn_scan).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View view){
      Intent i=new Intent(IntroViewActivity.this,QRview.class);
      i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
      i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
      startActivity(i);
    }
  }
);
  findViewById(R.id.btn_create).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View view){
      Snackbar mySnackbar=Snackbar.make(findViewById(R.id.introtop),"String_Node_Str",Snackbar.LENGTH_SHORT);
      mySnackbar.show();
    }
  }
);
  findViewById(R.id.btn_createNOW).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View view){
      EditText address=findViewById(R.id.address_text);
      EditText publickey=findViewById(R.id.public_text);
      EditText privatekey=findViewById(R.id.private_text);
      if (address.getText().toString().isEmpty() || publickey.getText().toString().isEmpty()) {
        Snackbar mySnackbar=Snackbar.make(findViewById(R.id.introtop),"String_Node_Str",Snackbar.LENGTH_SHORT);
        mySnackbar.show();
        return;
      }
      saveString("String_Node_Str",address.getText().toString());
      saveString("String_Node_Str",publickey.getText().toString());
      saveString("String_Node_Str",privatekey.getText().toString());
      Intent i=new Intent(IntroViewActivity.this,MainActivity.class);
      i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
      i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
      startActivity(i);
    }
  }
);
}