我正在使用Eclipse创建一个Android应用程序，用户可在其中输入彩票号码。然后，该应用程序使用Jsoup从最新的实时抽奖中检索彩票号码，以解析来自国家彩票网站的html彩票号码。然后用户按下检查按钮，之后打开新活动，显示用户号码和抽奖号码之间的匹配，以检查用户是否赢得了抽奖。在这一点上，我希望有一个按钮，允许用户打开彩票网页，以便他们检查他们的奖品，如果他们匹配他们的数字。但是我打开浏览器有困难。在用户输入他们的号码并点击检查按钮之后，程序崩溃，因此他们甚至没有达到将他们的号码与彩票号码进行比较的程度。我收到错误，我无法启动活动DisplayNumbersActivity，因为有一个空指针异常。任何人都可以帮我确定我的代码有什么问题或我如何解决它？提前致谢！我在下面列出了主要活动和DisplayNumbers活动代码。
public class DisplayNumbersActivity extends Activity {
private EditText urlText;
private Button checkWeb;
@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_numbers);
// Show the Up button in the action bar.
setupActionBar();
//get the message from the intent
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
//create the text view
TextView textView = new TextView(this);
textView.setTextSize(20);
textView.setTextColor(Color.RED);
textView.setText(message);
//set the text view as the activity layout
setContentView(textView);
urlText = (EditText) findViewById(R.id.url_field);
checkWeb = (Button) findViewById(R.id.checkWeb);
//set up event handlers
checkWeb.setOnClickListener (new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
openBrowser();
}//onClick
});//setOnClickListener
urlText.setOnKeyListener(new OnKeyListener() {
@Override
public boolean onKey(View view, int keyCode, KeyEvent event) {
// TODO Auto-generated method stub
if (keyCode == KeyEvent.KEYCODE_ENTER) {
openBrowser();
return true;
}
return false;
}//onKey
});//setOnKeyListener
}//onCreate
//open a browser on the URL specified in the text box
private void openBrowser() {
Uri uri = Uri.parse(urlText.getText().toString());
Intent intent = new Intent(Intent.ACTION_VIEW, uri);
startActivity(intent);
}//openBrowser
/**
* Set up the {@link android.app.ActionBar}, if the API is available.
*/
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
private void setupActionBar() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
getActionBar().setDisplayHomeAsUpEnabled(true);
}
}//setUpActionBar
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
// This ID represents the Home or Up button. In the case of this
// activity, the Up button is shown. Use NavUtils to allow users
// to navigate up one level in the application structure. For
// more details, see the Navigation pattern on Android Design:
//
// http://developer.android.com/design/patterns/navigation.html#up-vs-back
//
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}//onOptionsItemSelected
}//class
public class MainActivity extends Activity {
private final static String NATIONAL_LOTTERY_DRAW_URL = "http://www.national-lottery.co.uk/player/p/drawHistory.do";
public final static String EXTRA_MESSAGE = ".com.example.lottochecker.MESSAGE";
boolean bonus = false;
boolean jackpot = false;
int lottCount = 0;
Button check;
Integer [] numbers;
int bonusBall;
String userInput = "";
final int MAX = 49;
boolean validType = false;
int userGuess;
private LotteryDraw lotteryDraw;
@Override
//when the activity is created, call the layout class
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}//onCreate
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}//onCreateOptionsMenu
//called when the user clicks the send button
public void checkNumbers(View view) {
//set up an array of text boxes for the user to put in their numbers
EditText[] text_fields = new EditText[6];
//set up an array of string variables for holding user input
String[] str_nums = new String[6];
//set up an array to hold integer values having been converted from the user input as a String
int[] int_nums = new int[6];
//populate the array of text boxes with user input
text_fields[0] = (EditText) findViewById(R.id.enter_numbers);
text_fields[1] = (EditText) findViewById(R.id.enter_numbers2);
text_fields[2] = (EditText) findViewById(R.id.enter_numbers3);
text_fields[3] = (EditText) findViewById(R.id.enter_numbers4);
text_fields[4] = (EditText) findViewById(R.id.enter_numbers5);
text_fields[5] = (EditText) findViewById(R.id.enter_numbers6);
for(int i=0; i<6; i++)
{
str_nums[i] = text_fields[i].getText().toString();
// if the text box is empty, print error and stop processing.
// if not empty convert string to int and store in array
if(str_nums[i].equals(""))
{
Toast.makeText(MainActivity.this, "Please enter valid number in text box "+(i+1), Toast.LENGTH_LONG).show();
return;
}
else
{
int_nums[i] = Integer.parseInt(str_nums[i]);
}
}
// check validity of numbers entered
for(int i=0; i<6; i++)
{
// check numbers are in range
if (int_nums[i] < 1 || int_nums[i] > MAX)
{
Toast.makeText(MainActivity.this, "Number " + int_nums[i] + " in text box " + (i+1) + " is out of range. Please enter a number between 1 and 49", Toast.LENGTH_LONG).show();
return;
}
// check for duplicates
for(int j=0; j<6; j++)
{
if(i != j)
{
if (int_nums[i] == int_nums[j])
{
Toast.makeText(MainActivity.this, "The number " + int_nums[i] + " is dublicated in text boxes " + (i+1) + " and " + (j+1) + ". Duplicates can not be accepted", Toast.LENGTH_LONG).show();
return;
}
}
}
}
// numbers entered are valid
int matches = 0;
boolean bonus_match = false;
final int[] LOTTONUMBERS = lotteryDraw.getNumbers();
// check the 6 lotto numbers
for(int lotto_num = 0; lotto_num < 6; lotto_num++)
{
for(int user_num = 0; user_num < 6; user_num++)
{
if(LOTTONUMBERS[lotto_num] == int_nums[user_num])
{
matches++;
break;
}
}
}
// check the bonus ball
for(int user_num = 0; user_num < 6; user_num++)
{
if(lotteryDraw.getBonusBall() == int_nums[user_num])
{
bonus_match = true;
break;
}
}
//inform the user of the results
String output = "The lotto numbers are:\n";
for(int i=0; i<6; i++)
{
output = output + LOTTONUMBERS[i] + " ";
}
output = output + " bonus: " + lotteryDraw.getBonusBall();
output = output + "\n\nYour numbers are:\n";
for(int i=0; i<6; i++)
{
output = output + str_nums[i] + " ";
}
output = output + "\n\nYou have matched "+ matches + " numbers ";
if(bonus_match)
{
output = output + "and the bonus";
}
if(matches == 6)
{
output = output + "\n\nCONGRATULATIONS - YOU HAVE WON THE JACKPOT";
}
else if (matches >= 3)
{
output = output + "\n\nCONGRATULATIONS - you have won a prize";
}
else
{
output = output + "\n\nBad Luck - not enough matches to win";
}
//display the lottery results to the new activity
Intent intent = new Intent(this, DisplayNumbersActivity.class);
intent.putExtra(EXTRA_MESSAGE, output);
startActivity(intent);
}//method
public void getLotteryDrawFromWebsite(View view) {
ConnectivityManager connMgr = (ConnectivityManager)
getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
if (networkInfo != null && networkInfo.isConnected()) {
new DownloadWebpageTask().execute(NATIONAL_LOTTERY_DRAW_URL);
} else {
//TODO: add error info
}
}
private class DownloadWebpageTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... urls) {
// params comes from the execute() call: params[0] is the url.
try {
return downloadUrl(urls[0]);
} catch (IOException e) {
return "Unable to retrieve web page. URL may be invalid.";
}
}
// onPostExecute displays the results of the AsyncTask.
@Override
protected void onPostExecute(String result) {
lotteryDraw = extractLotteryDraw(result);
TextView tv = (TextView) findViewById(R.id.textView1);
tv.setText(lotteryDraw.toString());
//when the lottery draw has been received enable the check button for the user to check numbers
Button checkNumbers = (Button)findViewById(R.id.check);
checkNumbers.setEnabled(true);
//Log.d("DownloadWebpageTask", lotteryDraw.toString());
}
}
private String downloadUrl(String myurl) throws IOException {
InputStream is = null;
// Only display the first 100000 characters of the retrieved
// web page content.
int len = 200000;
try {
URL url = new URL(myurl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("POST");
conn.setDoInput(true);
conn.setRequestProperty( "User-agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4" );
// Starts the query
conn.connect();
is = conn.getInputStream();
// Convert the InputStream into a string
String contentAsString = readIt(is, len);
return contentAsString;
// Makes sure that the InputStream is closed after the app is
// finished using it.
} finally {
if (is != null) {
is.close();
}
}
}
private String readIt(InputStream stream, int len) throws IOException, UnsupportedEncodingException {
Reader reader = null;
reader = new InputStreamReader(stream, "UTF-8");
char[] buffer = new char[len];
reader.read(buffer);
return (new String(buffer)).trim();
}
private LotteryDraw extractLotteryDraw(String html) {
Log.d("extractLotteryDraw",html);
LotteryDraw lotteryDraw = new LotteryDraw();
Document doc = Jsoup.parse(html);
Elements elements = doc.getElementsByClass("drawhistory");
//System.out.println(elements.toString());
Element table = elements.first();
Element tbody = table.getElementsByTag("tbody").first();
Element firstLottoRow = tbody.getElementsByClass("lottorow").first();
Element dateElement = firstLottoRow.child(0);
System.out.println(dateElement.text());
Element gameElement = firstLottoRow.child(1);
System.out.println(gameElement.text());
Element noElement = firstLottoRow.child(2);
System.out.println(noElement.text());
String[] split = noElement.text().split(" - ");
int[] numbers = new int[split.length];
int i = 0;
for (String strNo : split) {
numbers[i] = Integer.valueOf(strNo);
i++;
}
lotteryDraw.setNumbers(numbers);
Log.v("DEBUG", "the value of numbers is " + numbers);
Element bonusElement = firstLottoRow.child(3);
Integer bonusBall = Integer.valueOf(bonusElement.text());
lotteryDraw.setBonusBall(bonusBall);
Log.v("DEBUG", "the value of numbers is " + numbers);
return lotteryDraw;
}//extractLotteryDraw
}//class
答案 0 :(得分：0)
在应用标记
内的 AndroidManifest.xml 中添加活动参考<activity android:name=".DisplayNumbersActivity"/>