Delete Canvas - Fill Canvas Android example

Sqlite3 create database and table with load.bat file and fill data to table example.

1. Create folder for your project: my_sqlite_project


2. Open folder and create file load.bat and paste to load.bat this text and save to project folder:
   

   
   
   
   sqlite3 my_database.s3db < load_text.sql
   
   pause
   
   
   
   




3. Create load_text.sql file and paste this text and save to project folder:
   

   
   CREATE TABLE [android_metadata] (
   
   [locale] TEXT
   
   );
   
   
   
   
   
   
   
   
   
   CREATE TABLE [my_table] (
   
   [_id] int NULL,
   
   [word] VARCHAR(255)  NULL,
   
   [description] VARCHAR(255)  NULL
   
   
   
   
   
   
   
   
   
   .separator ";"
   
   .import text_file.txt my_table
   
   
   
   



4. Create text_file.txt and paste this text and save it as UTF-8:
   

   
   1;word1;my first word
   
   2;word2; my second word 
   
   

   
   



5. Download sqlite3.exe and put to project folder.


6. Run BAT file load.bat and read text instruction from console


7. If database created you can open and edit this with sqlite database explorer


8. Copy database to Asses Android project folder


9. If you want using this database in Android application on device, you have to copy this database to folder on device /data/data/com.MyPackage/databases/

How to change the image dynamically in ImageView and button setOnClickListener Android sample.


Main.java

ipackage cz.okhelp.my_game;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;


public class Main extends Activity {
private ImageView hImageViewSemafor;
private Button hButton;
	
	@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        hImageViewSemafor = (ImageView)findViewById(R.id.idImageViewSemafor);
        hButton = (Button) findViewById(R.id.idBtnChangeImage);
        hButton.setOnClickListener(mButtonChangeImageListener);
 
 
       
       
    }
	
    View.OnClickListener mButtonChangeImageListener = new OnClickListener() {
        public void onClick(View v) {
                // setImageResource will change image in ImageView
        	hImageViewSemafor.setImageResource(R.drawable.semafor_green);
            
        }
    };

}

main.xml
Put into res/drawable this pictures:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="//schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
    
       <ImageView
            android:src="@drawable/semafor_red"
            android:id="@+id/idImageViewSemafor"
            android:background="#66FFFFFF"
            android:adjustViewBounds="true"
            android:maxWidth="47dip"
            android:maxHeight="91dip"
            android:padding="10dip"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />    
    
</LinearLayout>

For and continue statement in Java.

public class MainClass {
	public static void main(String[] arg) {
		String[] arrayOfString = { "Hello", "people", "hello", "world!" };

		for (int i = 0; i < arrayOfString.length; i++){
			if(arrayOfString[i].equals("hello"))
				continue; // skip to for
			System.out.println(arrayOfString[i]);
		}
	}
}
/*
Hello
people
world!
*/

How add pair of strings to Hashtable, how get pair key value from Hashtable, how split string, basic Java Android example.

MainClass.java

import java.util.Enumeration;
import java.util.Hashtable;
public class MainClass {
	public static void main(String[] arg) {
		
		// english;germany dictionary
		String[] arrayOfString = { "one;eine", "two;zwei", "three;drei" };

	    Hashtable<String, String> hashTable = new Hashtable<String, String>();
	    for(String s: arrayOfString){
	    	String[] array = s.split(";");
	    	String sKey ="", sValue="";
	    	if(array.length > 1){
	    	sKey = array[0]; sValue = array[1];
	    		hashTable.put(sKey, sValue);
	    	}
	    }

	    Enumeration<String> enumer = hashTable.keys();
	    while (enumer.hasMoreElements()) {
	      String keyFromTable = (String) enumer.nextElement();
	      // get Returns the value to which the specified key is mapped, 
	      // or null if this map contains no mapping for the key
	      System.out.println(keyFromTable + " = " + hashTable.get(keyFromTable));
	    }       

	    
	}
}
/*
two = zwei
one = eine
three = drei
 */

Terms Screen size, density, density independent pixel, resolution as a picture - pictogram.


Test your knowledge
Q: How to find out the phone screen size?
A: (By length of display diagonale in inch -  Not to measure a diagonal of device!!!)

Q: What resolution has 720 x 1280 display?
A: (921600 pixels)

Q: What does it mean "240 dpi" screen density?
A: (Display have density 240 x 240  dots - "Tri-color LED etc." - per every physical (real) square inch. If you have icon 240x240 pixels, this will just occupy an area of one square inch on the display.)

Q: Phone have screen density 240 dpi. Image for 160 dpi screen density have size 128x 128 pixels. What will be the size of the image for 240 dpi screen density?
A: (Calculate the virtual pixels size.   128 * (240/160)  =  192.  You have to resize image to new size 192 x 192 physical pixels and put into folder drawable-hdpi (high) ~240dpi  for phone with screen density 240 dpi. ) or use density independend pixels 128dp x 128dp.