如何在静态主或之后定义按钮和TextView？

Question

这是我的活动。我陷入了困境，需要帮助。 我需要读取数据，将它们作为关键字并生成地图＆lt;＆gt;。通过按键从用户获取密钥显示密钥的结果，然后在用户批准时将另一个按钮添加到列表中。

app.get('/*',(req,res) => {
    // send file as response
    // __dirname -- > points to current director
    res.sendFile(path.join(__dirname,'./index.html'));
})

我需要在main（）之后访问Buttons和TextViews。我尝试了几种方法但到目前为止没有成功。 我需要在main之后使用Buttons和TextViews。我需要地图＆lt;＆gt;在使用它们之前。 我试过让它们静态或在onCreate（）中定义但是没有成功。我感谢任何帮助。

我在得到答案后做了这个编辑 这是用作方法的Java文件

public class ExcelReaderActivity extends AppCompatActivity {


public static final String SAMPLE_XLSX_FILE_PATH = "/home/saeid/Documents/ABBREV.xlsx";
public static final Map<String, String> numberDescMap = new HashMap<>();

public final TextView productInput = findViewById(R.id.textView_InputProductNumber);
public final TextView productName = findViewById(R.id.textView_ProductName);
public final Button checkInput = findViewById(R.id.button_GO);
public final Button addInput = findViewById(R.id.button_AddProduct);

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


public static void main(String[] args) throws IOException, InvalidFormatException {

    // Creating a Workbook from an Excel file (.xls or .xlsx)
    Workbook workbook = WorkbookFactory.create(new File(SAMPLE_XLSX_FILE_PATH));

    // Retrieving the number of sheets in the Workbook
    System.out.println("Workbook has " + workbook.getNumberOfSheets() + " Sheets : ");

    // obtain a sheetIterator and iterate over it
    Iterator<Sheet> sheetIterator = workbook.sheetIterator();
    System.out.println("Retrieving Sheets using Iterator");
    while (sheetIterator.hasNext()) {
        Sheet sheet = sheetIterator.next();
        System.out.println("=> " + sheet.getSheetName());
    }

    // Getting the Sheet at index zero
    Sheet sheet = workbook.getSheetAt(0);
    Row rowCount = sheet.getRow(0);
    int totalNumberOfRows = sheet.getPhysicalNumberOfRows();
    int totalNumberOfColumns = rowCount.getPhysicalNumberOfCells();
    System.out.print("number of rows => " + totalNumberOfRows + "\n");
    System.out.print("number of columns => " + totalNumberOfColumns + "\n");

    // Create a DataFormatter to format and get each cell's value as String
    DataFormatter dataFormatter = new DataFormatter();

    // obtain a rowIterator and columnIterator and iterate over them
    System.out.println("\n\nIterating over Rows and Columns using Iterator\n");
    Iterator<Row> rowIterator = sheet.rowIterator();

    for (int currentRow = 1; currentRow < totalNumberOfRows; currentRow++){
        Row row = rowIterator.next();
        row = sheet.getRow(currentRow);
        Cell cell0 = row.getCell(0);
        Cell cell1 = row.getCell(1);
        String cellValue0 = dataFormatter.formatCellValue(cell0);
        String cellValue1 = dataFormatter.formatCellValue(cell1);
        numberDescMap.put(cellValue0,cellValue1);
        //System.out.print(currentRow + "-  *" + dbNumbers + "*" +  "*" + description + "*" + "\n");
    }

    List<String> dbNumbers = new ArrayList(numberDescMap.keySet());
    List<String> description = new ArrayList(numberDescMap.values());

    int checkIndex = 1;
    for (String mapkeys : dbNumbers){
        System.out.println(checkIndex++ + "- " + mapkeys + "==>" +numberDescMap.get(mapkeys) + "\n");
    }

    // Closing the workbook
    workbook.close();
}
}

}

我做了一个调试，工作簿总是为null，我在活动中得到null。

这就是我在活动中称之为

的方式

public class FileReader{
private final Activity activity;
public FileReader(Activity activity) {this.activity = activity;
}
public static final String SAMPLE_XLSX_FILE_PATH = "/home/saeid/Documents/ABBREV.xlsx";
public static final Map<String, String> numberDescMap = new HashMap<>();
public Map<String, String> ExcelFileReader() {
    // Creating a Workbook from an Excel file (.xls or .xlsx)
    Workbook workbook = null;
    try {
        workbook = WorkbookFactory.create(new File(SAMPLE_XLSX_FILE_PATH));
    } catch (IOException e) {
        e.printStackTrace();
    } catch (InvalidFormatException e) {
        e.printStackTrace();
    }

    // obtain a sheetIterator and iterate over it
    Iterator<Sheet> sheetIterator = workbook.sheetIterator();
    System.out.println("Retrieving Sheets using Iterator");
    while (sheetIterator.hasNext()) {
        Sheet sheet = sheetIterator.next();
        //System.out.println("=> " + sheet.getSheetName());
    }
    // Getting the Sheet at index zero
    Sheet sheet = workbook.getSheetAt(0);
    Row rowCount = sheet.getRow(0);
    int totalNumberOfRows = sheet.getPhysicalNumberOfRows();
    int totalNumberOfColumns = rowCount.getPhysicalNumberOfCells();
    System.out.println("number of rows => " + totalNumberOfRows );
    System.out.println("number of columns => " + totalNumberOfColumns );

    // Create a DataFormatter to format and get each cell's value as String
    DataFormatter dataFormatter = new DataFormatter();

    // 1. You can obtain a rowIterator and columnIterator and iterate over them
    System.out.println("\n\nIterating over Rows and Columns using Iterator\n");
    Iterator<Row> rowIterator = sheet.rowIterator();
    for (int currentRow = 1; currentRow < totalNumberOfRows; currentRow++) {
        Row row = rowIterator.next();
        row = sheet.getRow(currentRow);
        Cell cell0 = row.getCell(0);
        Cell cell1 = row.getCell(1);
        String cellValue0 = dataFormatter.formatCellValue(cell0);
        String cellValue1 = dataFormatter.formatCellValue(cell1);
        numberDescMap.put(cellValue0, cellValue1);
        //System.out.print(currentRow + "-  *" + dbNumbers + "*" +  "*" + description + "*" + "\n");
    }
    // Closing the workbook
    try {
        workbook.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return numberDescMap;
}

Answer 1

确保您正确理解活动生命周期。结帐link

您不需要使用 public static void main

    public class ExcelReaderActivity extends AppCompatActivity {

    public static final String SAMPLE_XLSX_FILE_PATH = "/home/saeid/Documents/ABBREV.xlsx";
    public static final Map<String, String> numberDescMap = new HashMap<>();

    public final TextView productInput ;
    public final TextView productName;
    public final Button checkInput ;
    public final Button addInput;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.reader_excel);
        productInput = findViewById(R.id.textView_InputProductNumber);
        productName = findViewById(R.id.textView_ProductName);
        checkInput = findViewById(R.id.button_GO);
        addInput = findViewById(R.id.button_AddProduct);
        createWorkbook();
    }


    createWorkbook(){

        // Creating a Workbook from an Excel file (.xls or .xlsx)
        Workbook workbook = WorkbookFactory.create(new File(SAMPLE_XLSX_FILE_PATH));

        // Retrieving the number of sheets in the Workbook
        System.out.println("Workbook has " + workbook.getNumberOfSheets() + " Sheets : ");

        // obtain a sheetIterator and iterate over it
        Iterator<Sheet> sheetIterator = workbook.sheetIterator();
        System.out.println("Retrieving Sheets using Iterator");
        while (sheetIterator.hasNext()) {
            Sheet sheet = sheetIterator.next();
            System.out.println("=> " + sheet.getSheetName());
        }

        // Getting the Sheet at index zero
        Sheet sheet = workbook.getSheetAt(0);
        Row rowCount = sheet.getRow(0);
        int totalNumberOfRows = sheet.getPhysicalNumberOfRows();
        int totalNumberOfColumns = rowCount.getPhysicalNumberOfCells();
        System.out.print("number of rows => " + totalNumberOfRows + "\n");
        System.out.print("number of columns => " + totalNumberOfColumns + "\n");

        // Create a DataFormatter to format and get each cell's value as String
        DataFormatter dataFormatter = new DataFormatter();

        // obtain a rowIterator and columnIterator and iterate over them
        System.out.println("\n\nIterating over Rows and Columns using Iterator\n");
        Iterator<Row> rowIterator = sheet.rowIterator();

        for (int currentRow = 1; currentRow < totalNumberOfRows; currentRow++){
            Row row = rowIterator.next();
            row = sheet.getRow(currentRow);
            Cell cell0 = row.getCell(0);
            Cell cell1 = row.getCell(1);
            String cellValue0 = dataFormatter.formatCellValue(cell0);
            String cellValue1 = dataFormatter.formatCellValue(cell1);
            numberDescMap.put(cellValue0,cellValue1);
            //System.out.print(currentRow + "-  *" + dbNumbers + "*" +  "*" + description + "*" + "\n");
        }

        List<String> dbNumbers = new ArrayList(numberDescMap.keySet());
        List<String> description = new ArrayList(numberDescMap.values());

        int checkIndex = 1;
        for (String mapkeys : dbNumbers){
            System.out.println(checkIndex++ + "- " + mapkeys + "==>" +numberDescMap.get(mapkeys) + "\n");
        }

        // Closing the workbook
        workbook.close();
    }
}

您可以使用 createWorkbook 方法

中的所有视图实例

Answer 2

Do like this 
public class ExcelReaderActivity extends AppCompatActivity {


public static final String SAMPLE_XLSX_FILE_PATH = "/home/saeid/Documents/ABBREV.xlsx";
public static final Map<String, String> numberDescMap = new HashMap<>();

private  TextView productInput, productName ;
private Button checkInput , addInput ;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.reader_excel);
 productName = findViewById(R.id.textView_ProductName);
 productInput = findViewById(R.id.textView_InputProductNumber);
 checkInput = findViewById(R.id.button_GO);
  addInput = findViewById(R.id.button_AddProduct);
 workBookCalculation(); 
}

public void workBookCalculation() throws IOException, InvalidFormatException {

    // Creating a Workbook from an Excel file (.xls or .xlsx)
    Workbook workbook = WorkbookFactory.create(new File(SAMPLE_XLSX_FILE_PATH));

    // Retrieving the number of sheets in the Workbook
    System.out.println("Workbook has " + workbook.getNumberOfSheets() + " Sheets : ");

    // obtain a sheetIterator and iterate over it
    Iterator<Sheet> sheetIterator = workbook.sheetIterator();
    System.out.println("Retrieving Sheets using Iterator");
    while (sheetIterator.hasNext()) {
        Sheet sheet = sheetIterator.next();
        System.out.println("=> " + sheet.getSheetName());
    }

    // Getting the Sheet at index zero
    Sheet sheet = workbook.getSheetAt(0);
    Row rowCount = sheet.getRow(0);
    int totalNumberOfRows = sheet.getPhysicalNumberOfRows();
    int totalNumberOfColumns = rowCount.getPhysicalNumberOfCells();
    System.out.print("number of rows => " + totalNumberOfRows + "\n");
    System.out.print("number of columns => " + totalNumberOfColumns + "\n");

    // Create a DataFormatter to format and get each cell's value as String
    DataFormatter dataFormatter = new DataFormatter();

    // obtain a rowIterator and columnIterator and iterate over them
    System.out.println("\n\nIterating over Rows and Columns using Iterator\n");
    Iterator<Row> rowIterator = sheet.rowIterator();

    for (int currentRow = 1; currentRow < totalNumberOfRows; currentRow++){
        Row row = rowIterator.next();
        row = sheet.getRow(currentRow);
        Cell cell0 = row.getCell(0);
        Cell cell1 = row.getCell(1);
        String cellValue0 = dataFormatter.formatCellValue(cell0);
        String cellValue1 = dataFormatter.formatCellValue(cell1);
        numberDescMap.put(cellValue0,cellValue1);
        //System.out.print(currentRow + "-  *" + dbNumbers + "*" +  "*" + description + "*" + "\n");
    }

    List<String> dbNumbers = new ArrayList(numberDescMap.keySet());
    List<String> description = new ArrayList(numberDescMap.values());

    int checkIndex = 1;
    for (String mapkeys : dbNumbers){
        System.out.println(checkIndex++ + "- " + mapkeys + "==>" +numberDescMap.get(mapkeys) + "\n");
    }

    // Closing the workbook
    workbook.close();
}
}

并在活动中的任何位置使用textview;