用按钮从片段转到活动。 Android Studio

Question

我正在尝试使Android Studio中的下一个代码无效，它不起作用。我想通过按钮将片段（GalleryFragment）传递给活动（postropa）。我已经将botton与函数（BotonPulsado）链接了，但不知道出了什么问题（在设计视图中）。

Design View

代码：

import (...)

public class GalleryFragment extends Fragment {

    private GalleryViewModel galleryViewModel;

    public View onCreateView(@NonNull LayoutInflater inflater,
                             ViewGroup container, Bundle savedInstanceState) {
        galleryViewModel =
                ViewModelProviders.of(this).get(GalleryViewModel.class);
        View root = inflater.inflate(R.layout.fragment_gallery, container, false);
        final TextView textView = root.findViewById(R.id.text_gallery);
        galleryViewModel.getText().observe(getViewLifecycleOwner(), new Observer<String>() {
            @Override
            public void onChanged(@Nullable String s) {
                textView.setText(s);
            }
        });
        return root;
    }

    public void BotonPulsado(View view) {
        Intent intent = new Intent(getContext(), postropa.class);
        startActivity(intent);
    }
}

Answer 1

您应该创建Button变量作为类字段。

private GalleryViewModel galleryViewModel;
Button button; <<-------

之后，您需要在方法onCreateView()中定义它>

 button = (Button) findViewById(R.id.button2);
并在此按钮上设置onClickListener()以处理呼叫。在那里，您必须调用启动活动的方法。

button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            BotonPulsado();
        }
    });
您的最终代码：

import (...)

public class GalleryFragment extends Fragment {

    private GalleryViewModel galleryViewModel;
    Button button;

    public View onCreateView(@NonNull LayoutInflater inflater,
                             ViewGroup container, Bundle savedInstanceState) {
        galleryViewModel =
                ViewModelProviders.of(this).get(GalleryViewModel.class);
        View root = inflater.inflate(R.layout.fragment_gallery, container, false);
        final TextView textView = root.findViewById(R.id.text_gallery);
        galleryViewModel.getText().observe(getViewLifecycleOwner(), new Observer<String>() {
            @Override
            public void onChanged(@Nullable String s) {
                textView.setText(s);
            }
        });
        button = (Button) findViewById(R.id.button2);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                BotonPulsado();
            }
        });
        return root;
    }

    public void BotonPulsado() {
        Intent intent = new Intent(getContext(), postropa.class);
        startActivity(intent);
    }
}