Uncaught TypeError при вызове функции Javascript в Android

Question

Я разработчик Android и новичок в JavaScript. Я контролирую веб-просмотр из своей активности с помощью javascript. На моей странице входа, когда я использую функции Java Script, я получаю некоторые огромные ошибки. Пожалуйста, направляйте меня, чтобы избежать этих ошибок.

Код:

web.loadUrl("javascript:document.getElementById(\"umail\").value = \"" 
     + email + "\";"); 
web.loadUrl("javascript:document.getElementById(\"password\").value = \"" 
     + pwd + "\";"); 
web.loadUrl("javascript:document.getElementById(\"confirmpassword\").value = \"" 
     + confirm_pwd + "\";"); 
web.loadUrl("javascript:func_register_step1('signin')"); 

web.loadUrl("javascript:window.JSInterface.getErrorMSG(document.getElementById('errormessagetd').innerHTML);"); 
web.loadUrl("javascript:window.JSInterface.getWarningMSG(document.getElementById('warning_msg').innerHTML);"); 

Ошибка:

05-15 11:52:28.310: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:28.310: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:28.310: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:28.310: E/Web Console(3722): Uncaught ReferenceError: func_register_step1 is not defined at null:1 
05-15 11:52:28.310: E/Web Console(3722): Uncaught TypeError: Cannot read property 'innerHTML' of null at null:1 
05-15 11:52:28.310: E/Web Console(3722): Uncaught TypeError: Cannot read property 'innerHTML' of null at null:1 
05-15 11:52:31.240: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:31.240: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:31.240: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:31.240: E/Web Console(3722): Uncaught ReferenceError: func_register_step1 is not defined at null:1 
05-15 11:52:31.250: E/Web Console(3722): Uncaught TypeError: Cannot read property 'innerHTML' of null at null:1 
05-15 11:52:31.250: E/Web Console(3722): Uncaught TypeError: Cannot read property 'innerHTML' of null at null:1 
05-15 11:52:33.590: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:33.590: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:33.590: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:33.590: E/Web Console(3722): Uncaught ReferenceError: func_register_step1 is not defined at null:1 
05-15 11:52:33.600: E/Web Console(3722): Uncaught TypeError: Cannot read property 'innerHTML' of null at null:1 
05-15 11:52:33.600: E/Web Console(3722): Uncaught TypeError: Cannot read property 'innerHTML' of null at null:1 
05-15 11:52:40.260: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:40.270: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:40.270: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:40.270: E/Web Console(3722): Uncaught ReferenceError: func_register_step1 is not defined at null:1 
05-15 11:52:40.270: E/Web Console(3722): Uncaught TypeError: Cannot read property 'innerHTML' of null at null:1 
05-15 11:52:40.270: E/Web Console(3722): Uncaught TypeError: Cannot read property 'innerHTML' of null at null:1 
05-15 11:52:41.290: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:41.290: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:41.290: E/Web Console(3722): Uncaught TypeError: Cannot set property 'value' of null at null:1 
05-15 11:52:41.290: E/Web Console(3722): Uncaught ReferenceError: func_register_step1 is not defined at null:1 
05-15 11:52:41.290: E/Web Console(3722): Uncaught TypeError: Cannot read property 'innerHTML' of null at null:1 
05-15 11:52:41.290: E/Web Console(3722): Uncaught TypeError: Cannot read property 'innerHTML' of null at null:1 

Answer 1

По выброшенных ошибок, кажется, что document.getElementById(...) возвращает нулевое значение. И поэтому применяя .value и .innerHTML для нулевого выброса ошибок.

Я подозреваю, что страница не загружается, когда вы вызываете функцию javascript. Когда вы называете свой javascript, я имею в виду, в каком методе? Чтобы убедиться, что страница загружена, вы можете позвонить loadUrl в методе onPageFinished объекта WebViewClient.