JAVA TIPS AND LOGICS

1. Conditional Operators

int value1 = 1;

int value2 = 2;

// AND Operator   "&&"

if((value1 == 1) && (value2 == 2))

// here Both statements are true condition is true other wise false
            System.out.println("value1 is 1 AND value2 is 2");

if((value1 == 2) && (value2 == 1))

            System.out.println("value1 is 2 AND value2 is 1");

// OR Operator   "||"

        if((value1 == 1) || (value2 == 1))

         // here Any one statements are true condition is true other wise false

            System.out.println("value1 is 1 OR value2 is 1");

    Output
             value1 is 1 AND value2 is 2
                   value1 is 1 OR  value2 is 1


2. Equality and Relational Operators

    int value1 = 1;

int value2 = 2;

         // Both values are equal this condition true
if (value1 == value2)
System.out.println("value1 == value2");
        // value1 not equal to value2 this condition is true
if (value1 != value2)
System.out.println("value1 != value2");              
if (value1 > value2)
System.out.println("value1 > value2");            
if (value1 < value2)
System.out.println("value1 < value2");
if (value1 <= value2)
System.out.println("value1 <= value2"); 

    Output
               value1 != value2
               value1 < value2
               value1 <= value2

3. Operators

     int result = 1 + 2; // result is now 3
        System.out.println(result);

        result = result - 1; // result is now 2
        System.out.println(result);

        result = result * 2; // result is now 4
        System.out.println(result);

        result = result / 2; // result is now 2
        System.out.println(result);

        result = result + 8; // result is now 10
        System.out.println(result);
        
        result = result % 7; // result is now 3
        System.out.println(result);   

    Output
             3 , 2, 4, 10, 3

4. if and else-if


        int testscore = 76;
        char grade;
        if (testscore >= 90) {
            grade = 'A';
        } else if (testscore >= 80) {
            grade = 'B';
        } else if (testscore >= 70) {
            grade = 'C';
        } else if (testscore >= 60) {
            grade = 'D';
        } else {
            grade = 'F';
        }
        System.out.println("Grade = " + grade);
  
    Output              

                   grade = 'C';

5. Loop While and for

        int count = 0;
        // While loop
        while (count < 11) {          
            System.out.println("Count while: " + count);
            count++;
        }            
           // for loop
            for(int i=0; i<11; i++){
                System.out.println("Count for: " + i);
        }

      Output
           Here Both outputs are same but conditions are different
                   Count while: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
                   Count for: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

6. for to loop through the array

int[] numbers = { 1,2,3,4,5,6,7,8,9,10 };
        for (int item : numbers) {
            System.out.println("Count is: " + item);
        }

    Output
           Count is: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

7. Number found in single Array-list(unlabeled break)

     // here number found in specific array list
int[] arrayOfInts =  { 32, 7, 3, 89, 12, 106, 20,  8012, 62, 51 };
       // search number is 12
        int searchfor = 12;
        int i;
        boolean foundIt = false;

        for (i = 0; i < arrayOfInts.length; i++) {
            if (arrayOfInts[i] == searchfor) {
                foundIt = true;
                break;
            }
        }
        if (foundIt) {
            System.out.println("Found " + searchfor + " at index " + i);
        } else {
            System.out.println(searchfor + " not in the array");
        }

      Output
             search number is in array list                     

                   // "Found " search number " at index " index number 

                   // here out put is number 12 this number in index 4
                      Found  12 at index  4

                   // number not found 
                      12  not in the array

8. for loops to search for a value in a two-dimensional array.

int[][] arrayOfInts = {      { 132, 817, 35, 589 },
                                                  { 12, 106, 200, 80 },
                                                  { 522, 12, 94, 150 }
                                          };
       int searchfor = 94;
       int i;
       int j = 0;
       boolean foundIt = false;
   search:
       for (i = 0; i < arrayOfInts.length; i++) {
           for (j = 0; j < arrayOfInts[i].length; j++) {
           
               if (arrayOfInts[i][j] == searchfor) {
                   foundIt = true;
                   break search;
               }
           }
       }
       if (foundIt) {
           System.out.println("Found " + searchfor + " at " + i + ", " + j);
       } else {
           System.out.println(searchfor + " not in the array");
       }

   Output
               // if 94 available in array list
                        Found 94 at 2, 2
                     // if specified number not in array list
                       number(94)  not in the array


9. program increments and find letter count in String.

 

String searchMe   = "peter piper picked a ppppp " +    "peck of pickled peppers";
int max = searchMe.length();
int letterCount = 0;

for (int i = 0; i < max; i++) {
// select specific letter here select "p" letter
if (searchMe.charAt(i) != 'p')
continue;  
letterCount++;
}
System.out.println("Found " + letterCount + " p's in the string."); 

      Output
            Found  14 p's in the string.

Simple free hand Paint with Color Changes using Color Picker

1.MAIN ACTIVITY 


import com.example.simplepaint.PickerDialog.OnColorChangedListener;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RelativeLayout;

public class MainActivity extends Activity {

private RelativeLayout relativelayout;

// Instance variables
private Paint mPaint, mBitmapPaint;
private MyView mView;
private Bitmap mBitmap;
private Canvas mCanvas;
private Path mPath;
private Button ClearPaint, Colorpaint;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

relativelayout = (RelativeLayout) findViewById(R.id.item);


DisplayMetrics metrics = getBaseContext().getResources().getDisplayMetrics();
int w = metrics.widthPixels;
int h = metrics.heightPixels;

System.out.println(" width " + w);
System.out.println(" height " + h);

mView = new MyView(this, w, h);
mView.setDrawingCacheEnabled(true);

mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.GREEN);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(5);

ClearPaint = (Button) findViewById(R.id.ClearPaint);
ClearPaint.setOnClickListener(new OnClickListener() {

public void onClick(View v) {
mBitmap.eraseColor(Color.TRANSPARENT);
mPath.reset();
mView.invalidate();
}
});

Button Colorpaint = (Button) findViewById(R.id.color);
Colorpaint.setOnClickListener(new OnClickListener() {

public void onClick(View v) {

int _color = R.color.red;
new PickerDialog(v.getContext(),new OnColorChangedListener()  {

         public void colorChanged(int color) {
         mPaint.setColor(color);
         Log.i("TAG", "mpaint one" +mPaint);
          }
      }, mPaint.getColor(), _color).show();
     Log.i("TAG", "mpaint two" +mPaint);
}
});    
relativelayout.addView(mView);
}

/*/// color changed function, getting value from ColorPickerDialog ///
public void colorChanged(int color) {
mPaint.setColor(color);
} */

// //////////******************* Pinting view *******************///////////////////

public class MyView extends View {

public MyView(Context c, int w, int h) {
super(c);
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
// Bitmap mBitmap =
// Bitmap.createScaledBitmap(originalBitmap,200,200,true);
mCanvas = new Canvas(mBitmap);
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
mBitmapPaint
.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
// mBitmap = Bitmap.createBitmap(bw, bh, Bitmap.Config.ARGB_8888);
// mCanvas = new Canvas(mBitmap);
}

@Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.TRANSPARENT);
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath(mPath, mPaint);
}

// //////************touching evants for painting**************///////
private float mX, mY;
private static final float TOUCH_TOLERANCE = 5;

private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}

private void touch_move(float x, float y) {
float dx = Math.abs(x - mX);
float dy = Math.abs(y - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
mX = x;
mY = y;
}
}

private void touch_up() {
mPath.lineTo(mX, mY);
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
mPath.reset();
}

@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
touch_up();
invalidate();
break;
}
return true;
} // end of touch events for image
}// end MyView
}

2.MAIN.XML


<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <RelativeLayout
        android:id="@+id/item"
        android:layout_below="@+id/linear"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

        <ImageView
            android:id="@+id/imageView"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_alignParentLeft="true"
            android:layout_alignParentTop="true"
            android:src="@drawable/cat" />

    </RelativeLayout>

    <LinearLayout
        android:id="@+id/linear"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" >

        <Button
            android:id="@+id/color"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="ChangeColor" />

        <Button
            android:id="@+id/ClearPaint"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="ClearPaint" />
    </LinearLayout>

</RelativeLayout>


 3. COLORPICKERVIEW ACTIVITY

import android.app.Dialog;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Shader;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;

public class PickerDialog extends Dialog {

    public interface OnColorChangedListener {
        void colorChanged(int color);
    }

    private OnColorChangedListener mListener;
    private int mInitialColor, mDefaultColor;
    //private String mKey;

private static class ColorPickerView extends View {

private Paint mPaint;
private float mCurrentHue = 0;
private int mCurrentX = 0, mCurrentY = 0;
private int mCurrentColor, mDefaultColor;
private final int[] mHueBarColors = new int[258];
private int[] mMainColors = new int[65536];
private OnColorChangedListener mListener;

ColorPickerView(Context c, OnColorChangedListener l, int color, int defaultColor)  {
super(c);
mListener = l;
mDefaultColor = defaultColor;

// Get the current hue from the current color and update the main color field
float[] hsv = new float[3];
Color.colorToHSV(color, hsv);
mCurrentHue = hsv[0];
updateMainColors();

mCurrentColor = color;

// Initialize the colors of the hue slider bar
int index = 0;
for (float i=0; i<256; i += 256/42) // Red (#f00) to pink (#f0f)
{
mHueBarColors[index] = Color.rgb(255, 0, (int) i);
index++;
}
for (float i=0; i<256; i += 256/42) // Pink (#f0f) to blue (#00f)
{
mHueBarColors[index] = Color.rgb(255-(int) i, 0, 255);
index++;
}
for (float i=0; i<256; i += 256/42) // Blue (#00f) to light blue (#0ff)
{
mHueBarColors[index] = Color.rgb(0, (int) i, 255);
index++;
}
for (float i=0; i<256; i += 256/42) // Light blue (#0ff) to green (#0f0)
{
mHueBarColors[index] = Color.rgb(0, 255, 255-(int) i);
index++;
}
for (float i=0; i<256; i += 256/42) // Green (#0f0) to yellow (#ff0)
{
mHueBarColors[index] = Color.rgb((int) i, 255, 0);
index++;
}
for (float i=0; i<256; i += 256/42) // Yellow (#ff0) to red (#f00)
{
mHueBarColors[index] = Color.rgb(255, 255-(int) i, 0);
index++;
}

// Initializes the Paint that will draw the View
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setTextAlign(Paint.Align.CENTER);
mPaint.setTextSize(12);
}

// Get the current selected color from the hue bar
private int getCurrentMainColor()
{
int translatedHue = 255-(int)(mCurrentHue*255/360);
int index = 0;
for (float i=0; i<256; i += 256/42)
{
if (index == translatedHue)
return Color.rgb(255, 0, (int) i);
index++;
}
for (float i=0; i<256; i += 256/42)
{
if (index == translatedHue)
return Color.rgb(255-(int) i, 0, 255);
index++;
}
for (float i=0; i<256; i += 256/42)
{
if (index == translatedHue)
return Color.rgb(0, (int) i, 255);
index++;
}
for (float i=0; i<256; i += 256/42)
{
if (index == translatedHue)
return Color.rgb(0, 255, 255-(int) i);
index++;
}
for (float i=0; i<256; i += 256/42)
{
if (index == translatedHue)
return Color.rgb((int) i, 255, 0);
index++;
}
for (float i=0; i<256; i += 256/42)
{
if (index == translatedHue)
return Color.rgb(255, 255-(int) i, 0);
index++;
}
return Color.RED;
}

// Update the main field colors depending on the current selected hue
private void updateMainColors()
{
int mainColor = getCurrentMainColor();
int index = 0;
int[] topColors = new int[256];
for (int y=0; y<256; y++)
{
for (int x=0; x<256; x++)
{
if (y == 0)
{
mMainColors[index] = Color.rgb(255-(255-Color.red(mainColor))*x/255, 255-(255-Color.green(mainColor))*x/255, 255-(255-Color.blue(mainColor))*x/255);
topColors[x] = mMainColors[index];
}
else
mMainColors[index] = Color.rgb((255-y)*Color.red(topColors[x])/255, (255-y)*Color.green(topColors[x])/255, (255-y)*Color.blue(topColors[x])/255);
index++;
}
}
}

@Override
protected void onDraw(Canvas canvas) {
int translatedHue = 255-(int)(mCurrentHue*255/360);
// Display all the colors of the hue bar with lines
for (int x=0; x<256; x++)
{
// If this is not the current selected hue, display the actual color
if (translatedHue != x)
{
mPaint.setColor(mHueBarColors[x]);
mPaint.setStrokeWidth(1);
}
else // else display a slightly larger black line
{
mPaint.setColor(Color.BLACK);
mPaint.setStrokeWidth(3);
}
canvas.drawLine(x+10, 0, x+10, 40, mPaint);
}

// Display the main field colors using LinearGradient
for (int x=0; x<256; x++)
{
int[] colors = new int[2];
colors[0] = mMainColors[x];
colors[1] = Color.BLACK;
Shader shader = new LinearGradient(0, 50, 0, 306, colors, null, Shader.TileMode.REPEAT);
mPaint.setShader(shader);
canvas.drawLine(x+10, 50, x+10, 306, mPaint);
}
mPaint.setShader(null);

// Display the circle around the currently selected color in the main field
if (mCurrentX != 0 && mCurrentY != 0)
{
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setColor(Color.BLACK);
canvas.drawCircle(mCurrentX, mCurrentY, 10, mPaint);
}

// Draw a 'button' with the currently selected color
mPaint.setStyle(Paint.Style.FILL);
mPaint.setColor(mCurrentColor);
canvas.drawRect(10, 316, 138, 356, mPaint);

// Set the text color according to the brightness of the color
if (Color.red(mCurrentColor)+Color.green(mCurrentColor)+Color.blue(mCurrentColor) < 384)
mPaint.setColor(Color.WHITE);
else
mPaint.setColor(Color.BLACK);
//canvas.drawText(getResources().getString(R.string.hello), 74, 340, mPaint);

// Draw a 'button' with the default color
mPaint.setStyle(Paint.Style.FILL);
mPaint.setColor(mDefaultColor);
canvas.drawRect(138, 316, 266, 356, mPaint);

// Set the text color according to the brightness of the color
if (Color.red(mDefaultColor)+Color.green(mDefaultColor)+Color.blue(mDefaultColor) < 384)
mPaint.setColor(Color.WHITE);
else
mPaint.setColor(Color.BLACK);
   //canvas.drawText(getResources().getString(R.string.hello), 202, 340, mPaint);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(276, 366);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() != MotionEvent.ACTION_DOWN) return true;
float x = event.getX();
float y = event.getY();

// If the touch event is located in the hue bar
if (x > 10 && x < 266 && y > 0 && y < 40)
{
// Update the main field colors
mCurrentHue = (255-x)*360/255;
updateMainColors();

// Update the current selected color
int transX = mCurrentX-10;
int transY = mCurrentY-60;
int index = 256*(transY-1)+transX;
if (index > 0 && index < mMainColors.length)
mCurrentColor = mMainColors[256*(transY-1)+transX];

// Force the redraw of the dialog
invalidate();
}
// If the touch event is located in the main field
if (x > 10 && x < 266 && y > 50 && y < 306)
{
mCurrentX = (int) x;
mCurrentY = (int) y;
int transX = mCurrentX-10;
int transY = mCurrentY-60;
int index = 256*(transY-1)+transX;
if (index > 0 && index < mMainColors.length)
{
// Update the current color
mCurrentColor = mMainColors[index];
// Force the redraw of the dialog
invalidate();
}
}
// If the touch event is located in the left button, notify the listener with the current color
if (x > 10 && x < 138 && y > 316 && y < 356)
mListener.colorChanged( mCurrentColor);

// If the touch event is located in the right button, notify the listener with the default color
if (x > 138 && x < 266 && y > 316 && y < 356)
mListener.colorChanged( mDefaultColor);

return true;
}
}

    public PickerDialog(Context context, OnColorChangedListener listener, int initialColor, int defaultColor) {
        super(context);

        mListener = listener;
      //  mKey = key;
        mInitialColor = initialColor;
        mDefaultColor = defaultColor;
    }
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
     
        OnColorChangedListener _ChangedListener = new OnColorChangedListener() {
            public void colorChanged( int color) {
                mListener.colorChanged(color);
                dismiss();
            }
        };

        setContentView(new ColorPickerView(getContext(), _ChangedListener, mInitialColor, mDefaultColor));
        setTitle("Color Picker");
    }
}

//Add this xml to  res/values 

4. COLOR.XML


<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="red">#ffff0000</color>
</resources>

1). we want choose any color use ing color picker  

Android Check Network Status

Android Check Network Status

public void CheckStatus() {  

 

ConnectivityManager connectionstate = (ConnectivityManager)               getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo network = connectionstate.getActiveNetworkInfo(); 

        

if (network != null && network.isConnected() == true) {

Toast.makeText(this, "Network Available", Toast.LENGTH_SHORT).show();

} else {

Toast.makeText(this, "Network Not Available", Toast.LENGTH_SHORT).show(); 

new AlertDialog.Builder(ChatsActivity.this)

            .setTitle("Connection failed")

            .setMessage("This application requires network access. Please, enable " + "mobile network or Wi-Fi.")

            

            .setPositiveButton("Accept", new DialogInterface.OnClickListener() {

            

                public void onClick(DialogInterface dialog, int which) {                         

                // Intent intent = new Intent(MainActivity.this, Settings.ACTION_WIRELESS_SETTINGS);

                // startActivity(intent);

                 ChatsActivity.this.startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));

                }

            })

            

            .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {

                public void onClick(DialogInterface dialog, int which) {

                 ChatsActivity.this.finish();

                }

            })

            .show();  

}

}

and also add these permissions in manifest.xml

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>