Simple Android thread and handler example
onCreate()
{
//layout and progress bar we have
//thread creation
thread = new Thread(new Mythread())
thread.start();
handler = new Handler()
{
handleMessage(Message msg)
{
//set value to progress bar
}
};
}
class Mythread implements Runnable
{
run()
{
//create Message object
for(int i =0;i<10;i++)
{
Message msg = Message.obtain();
msg.arg1 = i;
handler.sendMesahe(mg);
}
}
}
Download an image and send it to UI android httpurlconnection
private void downloadImage(String urlStr) {
progressDialog = ProgressDialog.show(this, "", "Downloading Image from " + urlStr);
final String url = urlStr;
new Thread() {
public void run() {
InputStream in = null;
Message msg = Message.obtain();
msg.what = 1;
try {
in = openHttpConnection(url);
bitmap = BitmapFactory.decodeStream(in);
Bundle b = new Bundle();
b.putParcelable("bitmap", bitmap);
msg.setData(b);
in.close();
}catch (IOException e1) {
e1.printStackTrace();
}
messageHandler.sendMessage(msg);
}
}.start();
}
private Handler messageHandler = new Handler() {
public void handleMessage(Message msg) {
super.handleMessage(msg);
ImageView img = (ImageView) findViewById(R.id.imageView);
img.setImageBitmap((Bitmap) (msg.getData().getParcelable("bitmap")));
progressDialog.dismiss();
}
};
Fibonacci series
class FibExample{
public static void main(String args[])
{
int n1=0,n2=1,n3,i,count=10;
System.out.print(n1+" "+n2);//printing 0 and 1
for(i=2;i<count;i++)//loop starts from 2 because 0 and 1 are already printed
{
n3=n1+n2;
System.out.print(" "+n3);
n1=n2;
n2=n3;
}
}}
Find duplicates in array
public class DuplicateArray {
public static void main(String[] args) {
int sample [] = {1,2,3,4,5,2,3,4,2,2,2};
HashMap<Integer ,Integer> testMap = new HashMap<Integer,Integer>();
for(int num : sample)
{
int i = 1;
if(!testMap.containsKey(num))
{
testMap.put(num, i);
}else
{
testMap.put(num, testMap.get(num)+1);
}
//System.out.println("print"+num);
}
for (HashMap.Entry<Integer, Integer> entry : testMap.entrySet()) {
System.out.println("Key : " + entry.getKey() + " Value : " + entry.getValue());
}
}
}
Reverse a String
public class ReverseString {
public static void main(String[] args) {
String test ="ABCD";
StringBuffer sb = new StringBuffer();
for(int i = test.length()-1 ;i>=0;i--)
{
sb.append(test.charAt(i));
}
System.out.println("print rev"+sb.toString());
}
}
Java Simple CallBack Example
public interface EventInterface {
public void notifyEventExample();
}
public class CallBack {
public EventInterface eI;
public CallBack(EventInterface eventInt)
{
this.eI = eventInt;
sendEvent();
}
public void sendEvent()
{
eI.notifyEventExample();
}
}
public class CallBackreceiver implements EventInterface {
public CallBackreceiver() { CallBack testCallBack = new CallBack(this); }
/* * public void testMethod() { testCallBack.sendEvent(); } */ public static void main(String args[]) {
CallBackreceiver receicer = new CallBackreceiver(); // receicer.testMethod();
}
public void notifyEventExample() { System.out.println("I'm Called"); }
}
Download an image from web service and load into an image view
@Override
protected Bitmap doInBackground(String... params) {
Bitmap bitmap = null;
try {
URL url = new URL(params[0]);
bitmap = BitmapFactory.decodeStream((InputStream)url.getContent());
} catch (IOException e) {
Log.e(TAG, e.getMessage());
}
return bitmap;
}
@Override
protected void onPostExecute(Bitmap bitmap) {
imageView.setImageBitmap(bitmap);
}
Reverse a string with out using String Buffer and String builder
public static String reverse(String source){
if(source == null || source.isEmpty()){
return source;
}
String reverse = "";
for(int i = source.length() -1; i>=0; i--){
reverse = reverse + source.charAt(i);
}
return reverse;
}
Alternate thread printing odd and even
public class PrintOddEvenInSequence {
private boolean isOddPrinting = false;
private boolean isEvenPrinting = false;
private int oddNum = 0;
private int evenNum = 0;
public static void main (String args[]) {
final PrintOddEvenInSequence oddEvenInSequence = new PrintOddEvenInSequence();
Thread printOddNumThread = new Thread(new Runnable() {
public void run() {
oddEvenInSequence.printOddNumber();
}
});
printOddNumThread.start();
Thread printEvenNumThread = new Thread(new Runnable() {
public void run() {
oddEvenInSequence.printEvenNumber();
}
});
printEvenNumThread.start();
}
private void printOddNumber() {
synchronized (this) {
while (true) {
while (isEvenPrinting) {
try {
System.out.println("Waiting to print odd number");
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
isOddPrinting = true;
System.out.println(++oddNum);
isOddPrinting = false;
notify();
}
}
}
private void printEvenNumber() {
synchronized (this) {
while (true) {
while (isOddPrinting) {
try {
System.out.println("Waiting to print even number");
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
isEvenPrinting = true;
System.out.println(++evenNum);
isEvenPrinting = false;
notify();
}
}
}
}
Find number of repeating characters in a string
public class Testmain {
public static void main(String args[])throws Exception{
int count = 0;
String s = "ABCDABD";
for(int i = 0;i<s.length();i++)
{
for(int j = i+1;j<s.length();j++)
{
if(s.charAt(i)==s.charAt(j))
{
count++;
System.out.println("repeated character is "+s.charAt(i));
}
}
}
System.out.println("count "+count);
}
}
Remove Specific character from string
public static String removeCharInString (String string, char charToBeRemoved) {
if (string == null)
return "";
StringBuilder strBuild = new StringBuilder ();
for (int i = 0; i < string.length (); i++) {
char chr = string.charAt (i);
if (chr == charToBeRemoved)
continue;
strBuild.append (chr);
}
return strBuild.toString ();
}
}
