Get the color of a specific pixel Java Android example

While cycle Java basic example with array of strings.

MainClass.java

public class MainClass {
	public static void main(String[] arg) {
		String[] arrayOfString = { "Hello", "people", "hello", "world!" };
                int i = 0;
		while ( i < arrayOfString.length ){
			System.out.println(arrayOfString[i]);
			i++;
		}
	}
}

Log.e println needs a message error.
E/AndroidRuntime(330): FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{b.paint/b.paint.MainActivity}: java.lang.NullPointerException: println needs a message

Try this code:

		// Error
                String s = null;
		Log.e("bla", s); // !!! error Log.e println needs a message error.
                // OK
		String s = null;
		Log.e("bla", s+""); // OK 

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>

Long press by finger on screen
From dialogue select Widgets
Select your widget
Put your widget on the screen

Video tutorial - to add home screen widgets - Android 2.1

InputStream, getResources(),openRawResource()

 java.io.InputStream is;
is = context.getResources().openRawResource(R.drawable.my_image);

Drawable mDrawable = context.getResources().getDrawable(R.drawable.button);
mDrawable.setBounds(150, 20, 300, 100);


Drawable[] mDrawables;
int[] resIDs = new int[] {
                R.drawable.btn_ok,
                R.drawable.btn_storno,
                R.drawable.btn_help
            };
            mDrawables = new Drawable[resIDs.length];
            Drawable prev = mDrawable;
            for (int i = 0; i < resIDs.length; i++) {
                mDrawables[i] = context.getResources().getDrawable(resIDs[i]);
                mDrawables[i].setDither(true);
                addToTheRight(mDrawables[i], prev);
                prev = mDrawables[i];
            }