错误NullPointerException

Question

此时我需要你们的帮助，我有以下代码，但是当我在日食中运行时，它完全是错误的，（错误是在下面的代码中签名）

package com.example.search;
import java.util.Calendar;
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.content.Intent;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.TextView;
import com.example.database.search.DBDataSource;
import com.example.database.search.Sma;

public class EditData extends Activity implements OnClickListener 
{   

int hour, minute, mYear,mMonth, mDay;
    static final int DATE_DIALOG_ID = 1;
    private EditText txtDate;
    private String[] arrMonth{"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"};
private DBDataSource dataSource; 
private long id;
private String Nama;
private String Alamat;
private Long Latitude;
private Long Longtitude;
private String Tanggal;
private String Email;
private String Website;
private String Facebook;
private String Twtitter;
private EditText edNama_sma, edAlamat_sma, edLatitude, edLongtitude, edTanggal, edEmail, edWebsite, edFacebook, edTwitter;
private TextView txId;
private Button btnSave;
private Button btnCancel;
private Sma sma;

@Override
public void onCreate(Bundle savedInstanceState)
{
      super.onCreate(savedInstanceState);
      setContentView(R.layout.edit_data);       
      //inisialisasi variabel
      edNama_sma    = (EditText) findViewById(R.id.editText_nama);
      edAlamat_sma  = (EditText) findViewById(R.id.editText_alamat);
      edLatitude    = (EditText) findViewById(R.id.editText_latitude);
      edLongtitude  = (EditText) findViewById(R.id.editText_longtitude);
      edTanggal     = (EditText) findViewById(R.id.editText_Tanggal);
      edEmail       = (EditText) findViewById(R.id.editText_Email);
      edWebsite     = (EditText) findViewById(R.id.editText_Website);
      edFacebook    = (EditText) findViewById(R.id.editText_Facebook);
      edTwitter     = (EditText) findViewById(R.id.editText_Twitter);

      txId = (TextView) findViewById(R.id.text_id_barang);


      // get the current date
        final Calendar c = Calendar.getInstance();
        mYear   = c.get(Calendar.YEAR);
        mMonth  = c.get(Calendar.MONTH);
        mDay    = c.get(Calendar.DAY_OF_MONTH);

       //WHEN  I ADD THIS CODE BELOW, then >> ERROR is happend >> java.lang.NullPointerExceptions
       //THIS FUNCTION IS USE FOR SHOWING DATETIMEPICKER 
        txtDate.setOnTouchListener(new View.OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                // TODO Auto-generated method stub
                showDialog(DATE_DIALOG_ID);
                return true;

            }
        });
      //UNTIL THIS LINE
      dataSource = new DBDataSource(this);
      dataSource.open();
      // ambil data sma dari extras
      Bundle bun = this.getIntent().getExtras();
      id            = bun.getLong("id");
      Nama          = bun.getString("Nama");
      Alamat        = bun.getString("Alamat");
      Latitude      = bun.getLong("Latitude");
      Longtitude    = bun.getLong("Longtitude");
      Tanggal       = bun.getString("Tanggal");
      Email         = bun.getString("Email");
      Website       = bun.getString("Website");
      Facebook      = bun.getString("Facebook");
      Twtitter      = bun.getString("Twitter");


      txId.append(String.valueOf(id));
      edNama_sma.setText(Nama);
      edAlamat_sma.setText(Alamat);
      edLatitude.setText(Latitude.toString());
      edLongtitude.setText(Longtitude.toString());
      edTanggal.setText(Tanggal);
      edEmail.setText(Email);
      edWebsite.setText(Website);
      edFacebook.setText(Facebook);
      edTwitter.setText(Twtitter);
      //set listener pada tombol
      btnSave = (Button) findViewById(R.id.button_save_update);
      btnSave.setOnClickListener(this);
      btnCancel = (Button) findViewById(R.id.button_cancel_update);
      btnCancel.setOnClickListener(this);
}
@Override
protected Dialog onCreateDialog(int id)
{
    switch (id) 
    {
        case DATE_DIALOG_ID:
            return new DatePickerDialog(this, mDateSetListener, mYear, mMonth, mDay);
    }
    return null;
}

private DatePickerDialog.OnDateSetListener mDateSetListener = new DatePickerDialog.OnDateSetListener()
{
        @Override
        public void onDateSet(DatePicker view, int year, int monthOfYear,int dayOfMonth) 
        {
            mYear = year;
            mMonth = monthOfYear;
            mDay = dayOfMonth;
            String sdate = arrMonth[mMonth] + " " + LPad(mDay + "", "0", 2) + ", " + mYear;
            txtDate.setText(sdate);
        }
    };
    private static String LPad(String schar, String spad, int len) 
    {
        String sret = schar;
        for (int i = sret.length(); i < len; i++) 
        {
            sret = spad + sret;
        }
        return new String(sret);
    }

@Override
public void onClick(View v) 
{
    // TODO Auto-generated method stub
    switch(v.getId())
    {
    // apabila tombol save diklik (update barang)
    case R.id.button_save_update :
        String ltd = edLatitude.getText().toString();
        String lotd = edLongtitude.getText().toString();
        Long latitude = Long.parseLong(ltd);
        Long longtitude = Long.parseLong(lotd);
        sma = new Sma();
        sma.setNama(edNama_sma.getText().toString());
        sma.setAlamat(edAlamat_sma.getText().toString());
        sma.setLatitude(latitude);
        sma.setLongitude(longtitude);
        sma.setEmail(edEmail.getText().toString());
        sma.setTgl_berdiri(edTanggal.getText().toString());
        sma.setWebsite(edWebsite.getText().toString());
        sma.setFacebook(edFacebook.getText().toString());
        sma.setTwitter(edTwitter.getText().toString());

        sma.setId(id);
        dataSource.updateBarang(sma);
        Intent i = new Intent(this, ViewData.class);
        startActivity(i);
        EditData.this.finish();
        dataSource.close();
        break;

    case R.id.button_cancel_update :
        finish();
        dataSource.close();
        break;
    }
  }
}

任何人都可以帮助我解决这个错误，我真的要感谢所有能够解决此代码的人，谢谢：D

Answer 1

您尚未初始化txtDate EtidText。

txtDate = (EditText) findViewById(R.id.txtDate);// or what ever you add the id for txtDate

那你就没事了。