android-emulator - Running an android application

Question

I am having trouble when I am trying to run my simple android applications On my system I tested for some other applications which were not created on my system and those worked well but when I edit those on my system then also these applications wont work. I am getting many errors

09-26 07:23:55.458: E/AndroidRuntime(1341):     ... 11 more
    at com.calculation.MainActivity.<init>(MainActivity.java:19)
    at java.lang.Class.newInstanceImpl(Native Method)
:   at java.lang.Class.newInstance(Class.java:1130)
    at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2128)

Why am I getting this Please Help me

package com.calculation;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import android.app.AlertDialog;
import android.content.DialogInterface;

public class MainActivity extends Activity {

    EditText value1,value2;
    Button add;
    TextView display;
    int num1=0, num2=0, total=0;
    final AlertDialog alertdialog= new AlertDialog.Builder(MainActivity.this).create();
    @SuppressWarnings("deprecation")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        value1=(EditText)findViewById(R.id.input1);
        value2=(EditText)findViewById(R.id.input2);
        add=(Button)findViewById(R.id.btnadd);
        display=(TextView)findViewById(R.id.result);
        if(value1==null)
        {
            alertdialog.setTitle("AlertDialog");
            alertdialog.setMessage("Please Enter a Valid Input");
            alertdialog.setIcon(R.drawable.ic_launcher);
            alertdialog.setButton("Ok", new DialogInterface.OnClickListener() {

                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // TODO Auto-generated method stub
                    Toast.makeText(getApplicationContext(), "You Clicked OK" , Toast.LENGTH_LONG).show();
                }
            });
        }
        else if(value2==null)
        {
            alertdialog.setTitle("AlertDialog");
            alertdialog.setMessage("Please Enter a Valid Input");
            alertdialog.setIcon(R.drawable.ic_launcher);
alertdialog.setButton("Ok", new DialogInterface.OnClickListener() {

                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // TODO Auto-generated method stub
                    Toast.makeText(getApplicationContext(), "You Clicked OK" , Toast.LENGTH_LONG).show();
                }
            });
        }
          add.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub

                num1=Integer.parseInt(value1.getText().toString());
                num2=Integer.parseInt(value2.getText().toString());
                total=num1+num2;
                display.setText("ADDITION IS"+total);
            }
        });


    }

}

Answer 1

The Problem was of api levels the apps which were tested were created many years back in different api level and environment so the alert dialog error was coming alert dialog can be in this way

private void showinvalidemail() {
        // TODO Auto-generated method stub
        AlertDialog.Builder dialogbuilder = new AlertDialog.Builder(this);
        dialogbuilder.setTitle("Invalid Email");
        dialogbuilder.setMessage("Please Enter Valid Email");
        dialogbuilder.setIcon(R.drawable.mexit);
        dialogbuilder.setPositiveButton("Ok",
                new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface arg0, int arg1) {
                        // TODOAuto-generated method stub
                        Toast.makeText(getApplicationContext(),
                                "You Clicked OK", Toast.LENGTH_LONG).show();
                    }
                });
        AlertDialog alertdialog = dialogbuilder.create();
        alertdialog.show();
    }