Fragment FragmentBasic.zip null pointer TextView article
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Example have error code:
//developer.android.com/training/basics/fragments/creating.html
Try to change ArticleFragment.java
//developer.android.com/training/basics/fragments/creating.html
Try to change ArticleFragment.java
/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* //www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.fragments;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class ArticleFragment extends Fragment {
final static String ARG_POSITION = "position";
int mCurrentPosition = -1;
TextView articleText;
@Override
// public View onCreateView(LayoutInflater inflater, ViewGroup container,
// Bundle savedInstanceState) {
//
// // If activity recreated (such as from screen rotate), restore
// // the previous article selection set by onSaveInstanceState().
// // This is primarily necessary when in the two-pane layout.
// if (savedInstanceState != null) {
// mCurrentPosition = savedInstanceState.getInt(ARG_POSITION);
// }
//
// // Inflate the layout for this fragment
// return inflater.inflate(R.layout.article_view, container, false);
// }
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// If activity recreated (such as from screen rotate), restore
// the previous article selection set by onSaveInstanceState().
// This is primarily necessary when in the two-pane layout.
if (savedInstanceState != null) {
mCurrentPosition = savedInstanceState.getInt(ARG_POSITION);
}
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.article_view, container, false);
articleText = (TextView) rootView.findViewById(R.id.article);
return rootView;
}
@Override
public void onStart() {
super.onStart();
// During startup, check if there are arguments passed to the fragment.
// onStart is a good place to do this because the layout has already been
// applied to the fragment at this point so we can safely call the method
// below that sets the article text.
Bundle args = getArguments();
if (args != null) {
// Set article based on argument passed in
updateArticleView(args.getInt(ARG_POSITION));
} else if (mCurrentPosition != -1) {
// Set article based on saved instance state defined during onCreateView
updateArticleView(mCurrentPosition);
}
}
public void updateArticleView(int position) {
//TextView article = (TextView) getActivity().findViewById(R.id.article); //Error: article=null.
if (articleText != null)
articleText.setText(Ipsum.Articles[position]);
mCurrentPosition = position;
}
/* ERROR public void updateArticleView(int position) {
TextView article = (TextView) getActivity().findViewById(R.id.article);
article.setText(Ipsum.Articles[position]);
mCurrentPosition = position;
}*/
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
// Save the current article selection in case we need to recreate the fragment
outState.putInt(ARG_POSITION, mCurrentPosition);
}
}
397LW NO topic_id
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Další témata ....(Topics)
If you create a button or view programmatically with OnClickListener you can set a tag key before button in parent layout is added.
And get correct button by this tag getTag() instead getId() in OnClickListener etc.
And get correct button by this tag getTag() instead getId() in OnClickListener etc.
Button button = new Button(getApplicationContext());
int idOfButton = button.getId(); // return -1
button.setTag("my_button");
String sTag = (String) button.getTag(); // return "my_button"
Calendar cal = new GregorianCalendar(), int year = cal.get(Calendar.YEAR),
ERA, MONTH, DAY_OF_MONTH, DAY_OF_WEEK, Android example code.
ERA, MONTH, DAY_OF_MONTH, DAY_OF_WEEK, Android example code.
public class MainActivity extends Activity {
TextView txtV;
Context cntx;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
txtV = (TextView)findViewById(R.id.idLabel);
cntx = this;
Calendar cal = new GregorianCalendar();
int era = cal.get(Calendar.ERA); // 0 B.C. before Christ, 1 Anno Domini
txtV.setText(txtV.getText() +"
" + era);
int year = cal.get(Calendar.YEAR); // 2011
txtV.setText(txtV.getText() +"
" + year);
int month = cal.get(Calendar.MONTH); // 0 is Januar
txtV.setText(txtV.getText() +"
" + month);
int day = cal.get(Calendar.DAY_OF_MONTH); // 1 to 31
txtV.setText(txtV.getText() +"
" + day);
int dayOfWeek = cal.get(Calendar.DAY_OF_WEEK); // 1=Sunday, 2=Monday ...
txtV.setText(txtV.getText() +"
" + dayOfWeek);
}
}
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new SampleView(this));
}
private static class SampleView extends View {
// CONSTRUCTOR
public SampleView(Context context) {
super(context);
setFocusable(true);
}
@Override
protected void onDraw(Canvas canvas) {
//drawARGB (int a, int r, int g, int b)
// a alpha component (0..255) of the color to draw onto the canvas
// r red component (0..255)
// g green component (0..255)
// b blue component (0..255)
canvas.drawARGB(255, 0, 255, 10);
}
}
}
If You create new xml file with prefix _ , for example _style.xml and You to clean project (Project->Clean), than package in folder project\gen will deleted with R.java class and new R.java not be created.
For to solving this problem You have to rename file without prefix _ as style.xml or name what You need and rebuild project.
If some ID cannot be resolved or is not a field get error occurence
You have to delete import android.R; in Activity.class if was inserted,
when this error is displayed.
For to solving this problem You have to rename file without prefix _ as style.xml or name what You need and rebuild project.
If some ID cannot be resolved or is not a field get error occurence
You have to delete import android.R; in Activity.class if was inserted,
when this error is displayed.
int[] mArrayOfInt;
String[] mArrayOfString;
List<String> mList;
public void saveState(Bundle map)
{
map.putIntArray("mArrayOfInt", mArrayOfInt);
map.putStringArray("mArrayOfString", mArrayOfString);
map.putStringArrayList("mList", mList);
}
public void restoreState(Bundle map)
{
mArrayOfInt= map.getIntArray("mArrayOfInt");
mArrayOfString = map.getStringArray("mArrayOfString");
mList = map.getStringArrayList("mList");
}
Editace: 2016-02-21 12:26:17
Počet článků v kategorii: 397
Url:fragment-fragmentbasic-zip-null-pointer-textview-article
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