问第二个活动的按钮跳转到不应该是的主要活动

EN

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
//DEFINE WHICH BUTTON TO CLICK ON
Button ButtonParent;
Button ButtonKid;

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

    ButtonParent=findViewById(R.id.buttonParent);
    ButtonKid=findViewById(R.id.buttonKid);
    ButtonParent.setOnClickListener(this);
    ButtonKid.setOnClickListener(this);
}
@Override
public void onClick(View view) {
        if (view==ButtonParent) {
            Intent intent_Parent = new Intent(MainActivity.this, ParentLogin.class);
            intent_Parent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
            startActivity(intent_Parent);
        }else if(view==ButtonKid) {
            Intent intent_Kid = new Intent(MainActivity.this, KidLogin.class);
            intent_Kid.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
            startActivity(intent_Kid);
        }
    }
}

public class ParentLogin extends AppCompatActivity implements View.OnClickListener{
EditText pName;
EditText pNRIC;
Button ParentLogin;
Button ParentRegister;

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

    pName = findViewById(R.id.LoginParentName);
    pNRIC = findViewById(R.id.ParentNRIC);

    ParentLogin=findViewById(R.id.LoginParentSubmit);
    ParentRegister=findViewById(R.id.LoginParentRegister);
    ParentLogin.setOnClickListener(this);
    ParentRegister.setOnClickListener(this);
}
@Override
public void onClick(View view) {
    if (view == ParentLogin) {

        String ParentName = pName.getText().toString().trim();
        String ParentNRIC = pNRIC.getText().toString().trim();
        boolean res = ParentDAO.checkParent(ParentName, ParentNRIC);
        if ((TextUtils.isEmpty(ParentName))||!(TextUtils.isEmpty(ParentNRIC))) {
            Toast toast= Toast.makeText(ParentLogin.this, "Please fill in all the empty columns which are available", Toast.LENGTH_SHORT);
            toast.setGravity(Gravity.CENTER_HORIZONTAL|Gravity.CENTER_VERTICAL,0,0);
            toast.show();

        } else {
            if (res) {
                Toast.makeText(ParentLogin.this, "Login Successfully", Toast.LENGTH_SHORT).show();
                Intent intent_parentActivity = new Intent(ParentLogin.this, ParentActivity.class);
                intent_parentActivity.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(intent_parentActivity);
            } else {
                Toast.makeText(ParentLogin.this, "Login not Successfully", Toast.LENGTH_SHORT).show();
            }
        }
    }else if(view==ParentRegister) {
        Intent intent_parentRegister = new Intent(ParentLogin.this, ParentRegistration.class);
        intent_parentRegister.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        startActivity(intent_parentRegister);
    }
}
}