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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

/*
 * 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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314

Every fragment must have an empty constructor Android Java Class | every-fragment-must-have-an-empty-constructor-android-java-class


You have to add constructor!

    public static class YourFragment extends Fragment {
    //you have to add constructor!!!!!	
    public YourFragment(){}

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            View view = inflater.inflate(R.layout.activity_main, container, false);

            return view;
        }   

    }

377

5. Fragments Tutorial Ipsum.java – Czech language | 5-fragments-tutorial-ipsum-java-czech-language


5. Fragments Tutorial Ipsum.java – Czech language


Dil 5. Ipsum.java
V 1. dílu jsme se něco dozvěděli od XML souborech a typu procesoru pro správný běh Android Studia a emulátoru různých typů zařizení s Androidem.
V 2. dílu jsme rozebrali MainActivity.java
V 3. dílu jsme se zabývali HeadlinesFragment.java
V 4. dílu jsme se podívali na ArticleFragment.java


V tomto dílu je na řadě Ipsum.java soubor.
Používáme příklad i zip porojekt z https://developer.android.com/training/basics/fragments/creating.html
Pozorně si jej nastudujte.


package com.example.android.fragments;
/** Ipsum je veřejná třída, která obsahuje
dvě pole řetězců - stringů.
Pole Headlines slouží jako uložiště pro názvy, které
budou načteny do ListView - seznamu v HeadlinesFragment.java
Pole Articles je v našem případě zásobárnou článků, které
budou načteny dle pozice položky ListView předané z HeadlinesFragment
zoětbě do MainActivity a
odtud do ArticleFragment.java, jako parametr metody
articleFrag.updateArticleView(position);
nebo jako argument Bundle
Bundle args = new Bundle();
    args.putInt(ArticleFragment.ARG_POSITION, position);
	
Stringy - ukládat do souboru java je ošemetné (problémy s kódováním, vyhledávání výrazů atd.) 
U většího množství článků pak nepřehledné.
Navíc, uživatel nemůže tento text editovat.
K ukládaní většího množství dat, k jejich vyhledávání 
a editaci je lépe používat databáze.	
*/
public class Ipsum {

    static String[] Headlines = {
        "Article One",
        "Article Two"
    };

    static String[] Articles = {
        "Article One


Excepteur pour-over occaecat squid biodiesel umami ... farm-to-table.", "Article Two

Vinyl williamsburg non ... synth, vegan carles odd future." }; }
385

EditText.setOnKeyListener not working on maxLines EditText | edittext-setonkeylistener-not-working-on-maxlines-edittext


Check this in XML file if use singleLine
singleLine change to maxLines (1 if singleLine)
declare inputType


        android:maxLines="1"
        android:inputType="text"

366

App have transparent menu Android | app-have-transparent-menu-android


If the app have transparent menu and you do not want this,
try delete @style/AppTheme in application tag in AndroidManifest.xml
and try run module - project. If menu is not transparent , maybe it caused

 <application
        android:allowBackup="true"
        android:icon="@drawable/dicts_ico"
        android:label="@string/app_name" 
        android:theme="@style/AppTheme" // delete this row - run app - try menu
 >


Or try set values\styles.xml into basic Theme

<resources>

    <!--
        Base application theme, dependent on API level. This theme is replaced
        by AppBaseTheme from res/values-vXX/styles.xml on newer devices.
    -->
    <style name="AppBaseTheme" parent="android:Theme.Black">
        <!--
            Theme customizations available in newer API levels can go in
            res/values-vXX/styles.xml, while customizations related to
            backward-compatibility can go here.
        -->
    </style>

    <!-- Application theme. -->
    <style name="AppTheme" parent="AppBaseTheme">
        <!-- All customizations that are NOT specific to a particular API-level can go here. -->
    </style>

</resources>

285

Unable to resolve target android | unable-to-resolve-target-android


Unable to resolve target android-7
Try this solution:
Select project from tree (project explorer)
- right click on project
- properties
- select Android from tree
- change Project Build Target to higher (or change project build target)
- selct from menu: Project-Clean ( select your project - OK)


Editace: 2016-02-21 12:26:17
Počet článků v kategorii: 397
Url:fragment-fragmentbasic-zip-null-pointer-textview-article

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