Question

我试图为我的DialogFragment实现一个onCompleteListener。但是在将片段附加到activity时会出错。如果我遗漏了

    public void onAttach(Activity activity) {
    try {
        this.mListener = (OnCompleteListener) activity;
    } catch (final ClassCastException e) {
        throw new ClassCastException(activity.toString()
                + " must implement OnCompleteListener");
    }
}

方法，对话框显示但是值没有传递回调用活动。我也为Activity实现了OnCompleteListener。这是我在调用活动中的实现

public class ViewMoreActivity extends FragmentActivity implements
    OnClickListener, BuySharesDialogFragment.OnCompleteListener {
-------------------------------
-------------------------------
    @Override
public void onComplete(String shares, String total_cost, String sharename,
        String paymentmode) {
    Toast.makeText(getApplicationContext(), shares, Toast.LENGTH_LONG)
            .show();
}

}

我的DialogFragment

public class BuySharesDialogFragment extends DialogFragment implements
    OnClickListener, OnItemSelectedListener {
    public static interface OnCompleteListener {
    public abstract void onComplete(String shares, String total_cost,
            String sharename, String paymentmode);
}

private OnCompleteListener mListener;
-------------------------------
-------------------------------
@Override
public void onClick(View v) {
    switch (v.getId()) {
    case R.id.button_cancel:
        getDialog().dismiss();
        break;
    case R.id.dialogbutton_buy_shares:
        this.mListener.onComplete(String.valueOf(shares), total_cost
                .getText().toString(), company_name.getText().toString(),
                paymentmethod);
        break;
    }
}


public void onAttach(Activity activity) {
    try {
        this.mListener = (OnCompleteListener) activity;
    } catch (final ClassCastException e) {
        throw new ClassCastException(activity.toString()
                + " must implement OnCompleteListener");
    }
}

我可能在哪里出错？堆栈跟踪错误指向onAttach（）方法。这是前几行

10-03 12:38:26.890: E/AndroidRuntime(5903): FATAL EXCEPTION: main
10-03 12:38:26.890: E/AndroidRuntime(5903): android.support.v4.app.SuperNotCalledException: Fragment BuySharesDialogFragment{405a5e38 #2 fragment_edit_name} did not call through to super.onAttach()
`10-03 12:38:26.890`: E/AndroidRuntime(5903):   at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:869)
10-03 12:38:26.890: E/AndroidRuntime(5903):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1088)

Answer 1

应该是

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
        this.mListener = (OnCompleteListener) activity;
    } catch (final ClassCastException e) {
        throw new ClassCastException(activity.toString() + " must implement OnCompleteListener");
    }
}

您忘了拨打super.onAttach(activity);

Answer 2

执行此更改

public void onAttach(Activity activity) {
     super.onAttach(activity); //UPDATE HERE
    try {
        this.mListener = (OnCompleteListener) activity;
    } catch (final ClassCastException e) {
        throw new ClassCastException(activity.toString()
                + " must implement OnCompleteListener");
    }
}

如何为DialogFragment实现onCompleteListener

2 个答案: