试图将对话框表单发布到http URL时显示空指针的Android对话框
我是android新手,这是我的问题,我有一个弹出的对话框表单,它假设使用android Http post将表单提交到URL,当我单击表单的提交按钮时,它强制关闭应用程序,我从logcat收到一条错误消息,说它是空指针试图将对话框表单发布到http URL时显示空指针的Android对话框,android,http,dialog,Android,Http,Dialog,我是android新手,这是我的问题,我有一个弹出的对话框表单,它假设使用android Http post将表单提交到URL,当我单击表单的提交按钮时,它强制关闭应用程序,我从logcat收到一条错误消息,说它是空指针 protected Dialog onCreateDialog(int id) { switch (id) { case DIALOG_TEXT_ENTRY: //This shows how to add a custom la
protected Dialog onCreateDialog(int id) {
switch (id) {
case DIALOG_TEXT_ENTRY:
//This shows how to add a custom layout to an AlertDialog
LayoutInflater factory = LayoutInflater.from(this);
final View textEntryView = factory.inflate(R.layout.commentlayout, null);
return new AlertDialog.Builder(HomeActivity.this)
.setIcon(R.drawable.ic_launcher)
.setTitle(R.string.app_name)
.setView(textEntryView)
.setPositiveButton(R.string.Submit, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
postComment();
}
})
.setNegativeButton(R.string.cancal, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
/* User clicked cancel so do some stuff */
}
}).create();
}
return null;
}
//this comes after the setContentView(R.Layout.view)
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.view);
public void postComment() {
nameField = (EditText) findViewById(R.id.editText1);
countryField = (EditText) findViewById(R.id.editText2);
commentField = (EditText) findViewById(R.id.commentField);
//get message from message fields
String name = nameField.getText().toString();
String count = countryField.getText().toString();
String comm = commentField.getText().toString();
//check whether the name field is empty or not
if (name.length() > 0) {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://_______");
try {
List < NameValuePair > nameValuePairs = new ArrayList < NameValuePair > (3);
nameValuePairs.add(new BasicNameValuePair("namet", name));
nameValuePairs.add(new BasicNameValuePair("countryt", count));
nameValuePairs.add(new BasicNameValuePair("commentt", comm));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
httpclient.execute(httppost);
nameField.setText(""); //reset the message text field
countryField.setText("");
commentField.setText("");
Toast.makeText(getBaseContext(), "Sent", Toast.LENGTH_SHORT).show();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
} else {
//display message if text field is empty
Toast.makeText(getBaseContext(), "All fields are required", Toast.LENGTH_SHORT).show();
}
只需替换nameField=EditText findViewByIdR.id.editText1;和其他2个具有以下代码
nameField = (EditText) textEntryView.findViewById(R.id.editText1);
countryField = (EditText) textEntryView.findViewById(R.id.editText2);
commentField = (EditText) textEntryView.findViewById(R.id.commentField);
编辑
为什么要添加textEntryView
答案是,当您使用任何布局时,它都有根视图。该根视图用于根据子视图的资源ID提取其子视图
当您在活动中选择两个不同的布局时,这意味着有两个根视图,其中一个由活动使用,可通过ActivityName.this.findViewById方法访问。但如果您想使用另一个布局,则需要添加另一个根视图的引用,该根视图位于您的案例textEntryView中。因此,只在该根中搜索儿童 假设以下视图来自R.layout.commentlayout 替换以下内容:
nameField = (EditText) findViewById(R.id.editText1);
countryField = (EditText) findViewById(R.id.editText2);
commentField = (EditText) findViewById(R.id.commentField);
与
你能从LogCat发布错误的stacktrace吗?你能告诉我在哪一个地方得到空指针异常吗?谢谢你们的回复,我在这里得到它,String name=nameField.getText.toString;nameField初始化了吗?如果你们有一个解决方案或者更好的方法,请回答,如果有效的话,我很乐意接受你们的回答。你可以编辑我发布的代码。我现在会尝试这种方法,并立即回复你。我会尝试这种方法,并回复你。谢谢你的回答。成功了。我刚试过。但是,请您解释一下为什么要将textEntryView添加到它中,这样可以帮助以后可能会遇到类似问题的其他人
nameField = (EditText) findViewById(R.id.editText1);
countryField = (EditText) findViewById(R.id.editText2);
commentField = (EditText) findViewById(R.id.commentField);
nameField = (EditText)dialog.findViewById(R.id.editText1);
countryField = (EditText)dialog.findViewById(R.id.editText2);
commentField = (EditText)dialog.findViewById(R.id.commentField);