Question

我已将按钮的可见性设置为“已消失”，但现在当我想设置按钮可见时，在尝试设置按钮的可见性时出现以下错误

    @Bind(R.id.btn1)
    Button btn1;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        View view = inflater.inflate(R.layout.hifragment_main, container, false);

      if(1==1) 
        {
            btn1.setVisibility(View.VISIBLE);
        }
        return view;
    }

Answer 1

您没有初始化按钮，请按以下方式初始化，

View view = inflater.inflate(R.layout.hifragment_main, container, false);
btn1 = (Button) view.findViewById(R.id.btn1);

Answer 2

您需要初始化按钮对象。

btn1 = (Button) findViewById(R.id.your_btn_id);

然后您可以查看if (btn1 != null)

Answer 3

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        View view = inflater.inflate(R.layout.hifragment_main, container, false);
        btn =view.findViewById(R.id.btn) // this line is important

        btn.setVisibility(View.VISIBLE);

        return view;
    }
//it's work for me .
`

尝试在空对象引用上调用虚方法'void android.widget.Button.setVisibility（int）'

3 个答案: