Android Studio .csv檔讀寫

可以先參考Android Studio 檔案讀寫內有寫關於Android Studio讀寫檔案基礎介紹

本次使用ArrayList存放CSV資料,使用RecyclerView顯示資料

建立ArrayList Data Model

新增DataModel的Java class

public class DataModel {

    private String ID;
    private String Name;
    private String Score;

    public DataModel(String ID, String Name, String Score){
        this.ID = ID;
        this.Name = Name;
        this.Score = Score;
    }

    public String getID(){
        return ID;
    }
    public String getName(){
        return Name;
    }
    public String getScore(){
        return Score;
    }
}

並在Activity內宣告ArrayList

ArrayList<DataModel> datalist = new ArrayList<>()

建立RecyclerView & Adapter

在建立Adapter之前可以先建立ViewHolder

public class ViewHolder extends RecyclerView.ViewHolder {
    public TextView idtext, nametext, scoretext;
    public ViewHolder(@NonNull View itemView) {
        super(itemView);
        idtext = (TextView) itemView.findViewById(R.id.idtext);
        nametext = (TextView) itemView.findViewById(R.id.nametext);
        scoretext = (TextView) itemView.findViewById(R.id.scoretext);
    }
}

新增MainAdapter的Java class

public class MainAdapter extends RecyclerView.Adapter<ViewHolder>{

    private LayoutInflater inflater;
    private ArrayList<DataModel> dataM;
    public MainAdapter(Context ctx, ArrayList<DataModel> datalist){

        this.inflater = LayoutInflater.from(ctx);
        this.dataM = datalist;

    }
    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = inflater.inflate(R.layout.recycle_item,parent,false);
        ViewHolder holder = new ViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        DataModel data = dataM.get(position);
        holder.idtext.setText(data.getID());
        holder.nametext.setText(data.getName());
        holder.scoretext.setText(data.getScore());
    }

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

建立RecyclerView與Adapter連接

GridLayoutManager layoutManager = new GridLayoutManager(context, 1);
recycler.setLayoutManager(layoutManager);
mainAdapter = new MainAdapter(context,datalist);
recycler.setAdapter(mainAdapter);

讀取CSV檔

try{
    File storage = Environment.getExternalStorageDirectory();
    File file = new File(storage + "/TXT" , "TXT.csv");
    InputStreamReader fw = new InputStreamReader(new FileInputStream(file), "UTF-8");
    BufferedReader bw = new BufferedReader(fw); //將BufferedWeiter與FileWrite物件做連結
    String thisLine ;
    String thisaplit = ",";
    while ((thisLine = bw.readLine()) != null) {
        String[] CSVdate = thisLine.split(thisaplit,3);//建立矩陣欄位為3,以","做資料分隔
        datalist.add(new DataModel(CSVdate[0],CSVdate[1],CSVdate[2]));//將資料放入ArrayList
    }
    mainAdapter.notifyDataSetChanged();
    bw.close();
}catch(Exception e){
    Log.d("ExceptionError","==" + e.getMessage());
    e.printStackTrace();
}

點擊RecyclerView輸入資料

新增OnItemClickListener的interface

public interface OnItemClickListener {
    void onItemClick(RecyclerView parent, View view, int position);
}

並在Adapter中加入

private OnItemClickListener mOnItemClickListener = null;
public void setOnItemClickListener(OnItemClickListener onItemClickListener){
    this.mOnItemClickListener = onItemClickListener;
}

在Adapter加入implements View.OnClickListener

public class MainAdapter extends RecyclerView.Adapter<ViewHolder> implements View.OnClickListener

加入methods

public void onClick(View view) {
    int position = recycler.getChildAdapterPosition(view);
    if (mOnItemClickListener!=null){
        mOnItemClickListener.onItemClick(recycler,view,position);
    }
}

在ViewHolder onCreateViewHolder補上

view.setOnClickListener(this);

public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view = inflater.inflate(R.layout.recycle_item,parent,false);
    ViewHolder holder = new ViewHolder(view);
    view.setOnClickListener(this);
    return holder;
}

點擊RecyclerView使用自訂AlertDialog輸入

mainAdapter.setOnItemClickListener(new OnItemClickListener(){
    @Override
    public void onItemClick(RecyclerView parent, View view, int position) {

        AlertDialog.Builder alertDialog = new AlertDialog.Builder(
                MainActivity.this);
        View v = getLayoutInflater()
                .inflate(R.layout.set_dialog_layout,null);
        Button btn_ok = v.findViewById(R.id.button_ok);
        Button btn_cancal = v.findViewById(R.id.buttonCancel);
        TextView titleName = v.findViewById(R.id.titleName);
        EditText editTextInput = v.findViewById(R.id.editTextInput);
        titleName.setText(datalist.get(position).getName());
        alertDialog.setView(v);
        alertDialog.setCancelable(false); //禁用返回
        AlertDialog dialog = alertDialog.create();
        dialog.show();
        btn_ok.setOnClickListener(view1 -> {
            if(editTextInput.length()!=0)
            {
                datalist.set(position , new DataModel(
                        datalist.get(position).getID(),
                        datalist.get(position).getName(),
                        editTextInput.getText().toString()));//更改list
                mainAdapter.notifyDataSetChanged();//adapter更新
                dialog.dismiss();

            }
        });

        btn_cancal.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view2) {
                dialog.cancel();
            }
        });
    }
});

寫入CSV

try {
    final StringBuilder sb = new StringBuilder();
    File storage = Environment.getExternalStorageDirectory();
    File file = new File(storage + "/TXT" , "TXT.csv");
    if (!file.exists()) {
        file.createNewFile();
    }
    FileOutputStream os = new FileOutputStream(file, false);//(檔案,是否接續寫入)
    for (int i = 0; i < datalist.size(); i++) {
        List<String> array = new ArrayList<>();//一行欄位
        array.add(datalist.get(i).getID());
        array.add(datalist.get(i).getName());
        array.add(datalist.get(i).getScore());
        for (int j = 0; j < array.size(); j++) {
            sb.append(array.get(j));
            if (j < array.size() - 1) {
                sb.append(",");
            } else {
                sb.append("\n");
            }
        }
    }
    os.write(sb.toString().getBytes("UTF-8"));//將資料以UTF-8型態寫入
    os.flush();
    os.close();
}catch(Exception e){
    Log.d("ExceptionError","==" + e.getMessage());
    e.printStackTrace();
}