我有两个碎片 side by side 加入 MainActivity LeftFragment 有一个 RecyclerView 具有 colors 我想在屏幕上设置背景色和文字 Right Fragment 当点击屏幕上的任何颜色时 左片段

应用程序因错误而崩溃 null object reference 错误

这是我的 Github Repo .但是,添加一些代码以供参考。

左片段

public class LeftFragment extends Fragment {

    public LeftFragment() {
        // Required empty public constructor
    }

    public static LeftFragment newInstance() {
        return new LeftFragment();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_left, container, false);

        //    private OnColorChooseListener mOnColorChooseListener;
        ArrayList<Color> mColor = new ArrayList<>();

        mColor.add(new Color(getResources().getColor(R.color.colorRed), getResources().getString(R.string.red)));
        mColor.add(new Color(getResources().getColor(R.color.colorOrange), getResources().getString(R.string.orange)));
        mColor.add(new Color(getResources().getColor(R.color.colorYellow), getResources().getString(R.string.yellow)));
        mColor.add(new Color(getResources().getColor(R.color.colorLime), getResources().getString(R.string.lime)));
        mColor.add(new Color(getResources().getColor(R.color.colorGreen), getResources().getString(R.string.green)));
        mColor.add(new Color(getResources().getColor(R.color.colorCyan), getResources().getString(R.string.cyan)));
        mColor.add(new Color(getResources().getColor(R.color.colorBlue), getResources().getString(R.string.blue)));
        mColor.add(new Color(getResources().getColor(R.color.colorIndigo), getResources().getString(R.string.indigo)));
        mColor.add(new Color(getResources().getColor(R.color.colorViolet), getResources().getString(R.string.violet)));

        RecyclerView mRecyclerView = view.findViewById(R.id.color_list_view);
        RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getActivity());
        RecyclerView.Adapter mAdapter = new ColorAdapter(mColor, getActivity());
        mRecyclerView.setLayoutManager(mLayoutManager);
        mRecyclerView.setAdapter(mAdapter);

        return view;
    }

}

右片段

public class RightFragment extends Fragment {

    ColorAdapter     colorAdapter;
    ArrayList<Color> color;

    public RightFragment() {
        // Required empty public constructor
    }

    public static RightFragment newInstance() {
        return new RightFragment();
    }


    @Override
    public View onCreateView(
            LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState
    ) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_right, container, false);

        final ConstraintLayout constraintLayout = view.findViewById(R.id.right_color_block);
        final TextView         textView         = view.findViewById(R.id.right_color_text);

        colorAdapter.SetItemClickListener(new ColorAdapter.OnItemClickListener() {
            @Override
            public void OnItemClick(int position) {
                constraintLayout.setBackgroundColor(color.get(position).getmColor());
                textView.setText(color.get(position).getmLabel());
            }
        });

        return view;
    }

}

颜色适配器(RecyclerView)

public class ColorAdapter extends RecyclerView.Adapter<ColorAdapter.ColorViewHolder> {

    private List<Color>         mColor;
    private Context             mContext;
    private OnItemClickListener mOnItemClickListener;

    public ColorAdapter(List<Color> mColor, Context mContext) {
        this.mColor = mColor;
        this.mContext = mContext;
    }

    public void SetItemClickListener(OnItemClickListener listener) {
        this.mOnItemClickListener = listener;
    }

    @NonNull
    @Override
    public ColorViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.color_list_item, viewGroup, false);
        return new ColorViewHolder(view, mOnItemClickListener);
    }

    @Override
    public void onBindViewHolder(@NonNull final ColorViewHolder colorViewHolder, final int i) {

        final Color color = mColor.get(i);

        colorViewHolder.itemColorText.setText(color.getmLabel());
        colorViewHolder.itemColorText.setBackgroundColor(color.getmColor());

        colorViewHolder.itemColorText.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(mContext, "Item clicked: " + i, Toast.LENGTH_SHORT).show();
//                colorViewHolder.feedbackBlock.setBackgroundColor(color.getmColor());
                colorViewHolder.feedbackText.setText(color.getmLabel());
            }
        });

    }

    @Override
    public int getItemCount() {
        return mColor.size();
    }

    public interface OnItemClickListener {
        void OnItemClick(int position);
    }

    class ColorViewHolder extends RecyclerView.ViewHolder {

        public ConstraintLayout itemColorBlock;
        public TextView         itemColorText;
        public ConstraintLayout feedbackBlock;
        public TextView         feedbackText;

        public ColorViewHolder(@NonNull View itemView, final OnItemClickListener listener) {
            super(itemView);

            itemColorBlock = itemView.findViewById(R.id.color_block);
            itemColorText = itemView.findViewById(R.id.color_text);
            feedbackBlock = itemView.findViewById(R.id.right_color_block);
            feedbackText = itemView.findViewById(R.id.right_color_text);

            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    if (listener != null) {
                        int position = getAdapterPosition();

                        if (position != RecyclerView.NO_POSITION) {
                            listener.OnItemClick(position);
                        }
                    }
                }
            });

        }
    }

}

颜色

public class Color {

    private int mColor;
    private String mLabel;

    public Color(@ColorInt int color, String label) {
        this.mColor = color;
        this.mLabel = label;
    }

    public String getmLabel() {
        return mLabel;
    }

    public void setmLabel(String mLabel) {
        this.mLabel = mLabel;
    }

    public int getmColor() {
        return mColor;
    }

    public void setmColor(@ColorInt int mColor) {
        this.mColor = mColor;
    }

    @NonNull
    @Override
    public String toString() {
        return super.toString();
    }
}

主要活动

public class MainActivity extends AppCompatActivity {

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

        LeftFragment leftFragment = LeftFragment.newInstance();
        getSupportFragmentManager().beginTransaction().replace(R.id.left_container, leftFragment).commit();

        RightFragment rightFragment = RightFragment.newInstance();
        getSupportFragmentManager().beginTransaction().replace(R.id.right_container, rightFragment).commit();

    }

}