Windows set Environment Variables - Java path

When Eclipse and the emulator runs.
To access the DDMS perspective, go to Window > Open Perspective > DDMS. If DDMS does not appear, go to Window > Open Perspective > Other ... and select DDMS.

Open Devices TAB. Window -> Show view -> Devices

From Devices TAB select Screen Capture

Generate random number Android Java example source code.

		Random rand = new Random();
		int i = rand.nextInt() % 256; // range -255  +255
		System.out.print(i + "

"); // -184
		i = Math.abs(rand.nextInt() % 12); // range 0  +11
		System.out.print(i); // 7

// Math.random() start with 0.  e.g. 0.35981234 
int nRan = (int) (Math.random()*10); // 0 - 10

// nextDouble(), nextFloat(), nextInt(), nextLong() returns 0 - 10
import java.util.Random;´

Random r = new Random();
int nRan = r.nextInt(); // 0 - 10
double dRan = r.nextDouble() * 10; // e.g. 7.496285271597397

nextDouble – return 0 - 1
nextFloat – same as double
nextInt –  -2147483648  +2147483647
nextLong –  -922337203685775808  +9223372036854775807
nextGaussian –  0.0 aberation 1.0.

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);
    }
}

Try each step separately:

1. Restart Eclipse


2. Clean project and rebuild


3. Create a new project and try it if the problem persists, if no move copy project to other folder, delete project from workspace , create new project same name and copy java, xml etc. files to new project


4. Close Eclipse, backup folder c:\Users\myName\workspace\.metadata and delete it. Restart Eclipse try again import project to workspace



5. Re-installing the Android Developer Tools



6. Re-installing Eclipse - rename old folder with Android to Android_old, create new folder C:\Program Files\Android and copy new Eclipse with sdk into new folder



7. Created a new project importing from the file system



8. Created a new project from subversion

Update TextView from TimerTask, Handler, schedule, run, cancel TimerTask, Android example

public class TimerActivity extends Activity {
	TimerTask mTimerTask;
	final Handler handler = new Handler();
	Timer t = new Timer();	
TextView hTextView;
TableRow hTableRow;
Button hButton, hButtonStop;


private int nCounter = 0;
@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        hTextView = (TextView)findViewById(R.id.idTextView);
        hButton = (Button)findViewById(R.id.idButton);
        hButton.setOnClickListener(mButtonStartListener);
        hButtonStop = (Button)findViewById(R.id.idButtonStop);
        hButtonStop.setOnClickListener(mButtonStopListener);

         
        
    } // end onCreate

View.OnClickListener mButtonStartListener = new OnClickListener() {
	public void onClick(View v) {
		doTimerTask();
    }
};



	
	View.OnClickListener mButtonStopListener = new OnClickListener() {
    	public void onClick(View v) {
    		stopTask();
    		
    	}
    };
    
    
    public void doTimerTask(){

    	mTimerTask = new TimerTask() {
    	        public void run() {
    	                handler.post(new Runnable() {
    	                        public void run() {
    	                        	nCounter++;
                                        // update TextView
    	                        	hTextView.setText("Timer: " + nCounter);

    	                        	Log.d("TIMER", "TimerTask run");
    	                        }
    	               });
    	        }};

            // public void schedule (TimerTask task, long delay, long period) 
    	    t.schedule(mTimerTask, 500, 3000);  // 

    	 }

    	  public void stopTask(){

    	   if(mTimerTask!=null){
    	      hTextView.setText("Timer canceled: " + nCounter);

    	      Log.d("TIMER", "timer canceled");
    	      mTimerTask.cancel();
    	 }
    
    }    
}