toLowerCase Locale toUperCase Locale Java Android

How set JAVA path to Environment Variables on Windows (7)
Select Start menu > Computer > System Properties > Advanced System Settings(properties).
Then open Advanced tab > Environment Variables and add a new system variable JAVA_HOME that points to your JDK folder, for example

 C:\Program Files\Java\jdk1.8.0_05

xml example source code with image.

   <TableLayout android:layout_width="match_parent" android:id="@+id/idTableInRadioGroup" android:layout_height="wrap_content">
        <TableRow android:id="@+id/tableRow1" android:layout_width="wrap_content" android:layout_height="wrap_content">


<RadioGroup android:id="@+id/idRadio_group_1_column"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginLeft="20dp"
            android:orientation="vertical">
 <RadioButton android:id="@+id/idRadio_1"
                android:text="@string/textLabel_1"/>
            <RadioButton android:id="@+id/idRadio_2"
                android:text="@string/textLabel_2"/>
            <RadioButton android:id="@+id/idRadio_3"
                android:text="@string/textLabel_3"/> 
 
        </RadioGroup>
<RadioGroup android:id="@+id/idRadio_group_2_column"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginLeft="20dp"
            android:orientation="vertical">
 
  <RadioButton android:id="@+id/idRadio_4"
                android:text="@string/textLabel_4"/>
            <RadioButton android:id="@+id/idRadio_5"
                android:text="@string/textLabel_5"/>
            <RadioButton android:id="@+id/idRadio_6"
                android:text="@string/textLabel_6"/>
        </RadioGroup>
</TableRow>        
    </TableLayout>

Toast in Android application is equivalent of Alert in JavaScript or MessageBox in WinApi.

// Toast android.widget.Toast.makeText(Context context, CharSequence text, int duration)
// public static Toast makeText (Context context, CharSequence text, int duration) 

Toast.makeText(getApplicationContext(), "Hello world!",
                  Toast.LENGTH_SHORT).show();

int occupy 4 bytes (32 bits) in memory

int in Java example of using Integer and Array of Integer and Iteger to String

        // get max end min values of int in Java example 4 bytes (32 bits) PC architecture
	System.out.println(Integer.MAX_VALUE); // 2147483647
	System.out.println(Integer.MIN_VALUE); // -2147483648


// members variable
private int mProgress = 10;

//integer to string java
int myInteger = 8;
String myString = Integer.toString(myInteger);

// a final variable can only be initialized once
static final int NUM_PARTICLES = 15;

 for (int i = 0; i < NUM_PARTICLES ; i++) { 
// do something
}

// int as return value of function
public int getCount() {
return 5;
}

// int as a parametr of function
public float getFloatFromInt(int i) {
float fRet = (float) i;
 return fRet;
}

//array of int
int[] anArray;              // declares an array of integers
          anArray = new int[2];      // allocates memory for 2 integers
          anArray[0] = 100; // initialize first element
          anArray[1] = 200; // initialize second element

for (int i = 0; i < anArray.length; i++) {
// print out values from anArray
System.out.println("Index: " + i);
System.out.println("Value: " + anArray[i]); 
}

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);
    }
}