Question

我正在尝试在MyActivity中创建一个片段，并将需要显示的数据传递给它。我目前正在尝试通过静态方法newInstance()

将所有数据打包到一个捆绑包中

但是，当我打开活动时，尝试在onCreateView()中打开捆绑包时会收到Null Pointer异常

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.os.Bundle.getInt(java.lang.String, int)' on a null object reference

这是在第一次调用getInt()时发生的，这使我认为getArguments()由于某种原因正在返回空包，而我不知道为什么会返回空包。

MyActivity.java

/* Create Status Bar fragment */
FragmentManager fragMngr = getSupportFragmentManager();
frag = (StatusBarFragment)fragMngr.findFragmentById(R.id.f_container2);
if (frag == null)
{
    frag = StatusBarFragment.newInstance(player.getMoney(),
                                         player.getHealth(),
                                         player.getEquipmentMass());
    fragMngr.beginTransaction().add(R.id.f_container2, frag).commit();
 }

StatusBarFragment.java

public class StatusBarFragment extends Fragment
{
    private static final String MONEY = "vg.my.citruscode.money";
    private static final String HEALTH = "vg.my.citruscode.health";
    private static final String EQUIPMENT_MASS = "vg.my.citruscode.equipmentMass";

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        View parentView = inflater.inflate(R.layout.fragment_status_bar, container, false);
        Bundle args = getArguments();

        // Omitted methods which update UI Elements
        updateMoney(args.getInt(MONEY, 0)); // This line causes exception
        updateHealth(args.getDouble(HEALTH, 0.0));
        updateEquipmentMass(args.getDouble(EQUIPMENT_MASS, 0.0));

        return parentView;
    }

    public static StatusBarFragment newInstance(int money, double health, double equipmentMass)
    {
        StatusBarFragment frag = new StatusBarFragment();
        Bundle args = new Bundle();

        args.putInt(MONEY, money);
        args.putDouble(HEALTH, health);
        args.putDouble(EQUIPMENT_MASS, equipmentMass);

        frag.setArguments(args);
        return frag;
    }
}

Answer 1

奇怪的方法。我认为args和数据之间缺少连接。在newInstance（）上执行此操作。MONEY= money和其他字符串。

检索捆绑参数时，为什么会出现Null指针异常？

1 个答案: