Android Custom Listener Example

Custom listener implemnatation in android with Full Sourcecode.
WorkHelper : Processing class  

package com.customlistener;

import android.location.Location;
import android.util.Log;

/**
 * @author piyush
 * Does data processing.
 */
public class WorkHelper {

 private HelperResult helperResult;
 private String tag="WorkHelper",resultString;
 private int randomNumber=-1,limit=1000;
 
 public WorkHelper(HelperResult helperResult) {
  this.helperResult=helperResult;
 }
 
 public void doProcessing()
 {
  //generate number between 0 to 1000
  randomNumber=(int)(Math.random()*limit);  
  Log.d(tag,"doProcessing:"+randomNumber);
  
  resultString="New RandomNumber is : "+randomNumber;
  //post data back to MainActivity
  helperResult.getResult(resultString);
 }
 
 public static abstract class HelperResult{
        public abstract void getResult(String resultString);
    }
}

MainActivity : UI Class

package com.customlistener;

import com.customlistener.WorkHelper.HelperResult;

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;

/**
 * Main Activity 
 * @author piyush
 */
public class MainActivity extends Activity {
 
 private String tag="HelperResult",resultStr="";
 private Button startButton;
 private WorkHelper workHelper;
 private Context context;
 private TextView textViewData;
 
 /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        
        setContentView(R.layout.main);
        context=this;
        workHelper=new WorkHelper(helperResult);
        
        startButton=(Button)findViewById(R.id.button1);
        textViewData=(TextView)findViewById(R.id.textDetail);
        
        startButton.setOnClickListener(new OnClickListener() {
   
   @Override
   public void onClick(View v) 
   {
    //generate random number
    workHelper.doProcessing();
   }
  });
    }
    
    /**
     * Create Instance of HelperResult Class
     * and Implement getResult().
     */
    HelperResult helperResult=new HelperResult() 
    {
     @Override
  public void getResult(String resultString) {
   Log.d(tag,"in MainActivity");
   Log.d(tag,"Result Received :"+resultString);
   resultStr+=resultString+"\n";
   textViewData.setText(resultStr);   
  }
 };
    
}

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