Android Dialog Example , post on : http://phonbopit.com/how-to-show-android-dialog/

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:padding="16dp">

    <TextView
        android:text="Android Dialog Example"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/text_title"
        android:textSize="22sp"
        android:textColor="#D74B4C"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="8dp"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button_dialog_simple"
        android:text="Simple Dialog"
        android:gravity="center"
        android:padding="16dp"
        android:textSize="20sp"
        android:textColor="#FFFFFF"
        android:background="#D74B4C"
        android:layout_marginTop="16dp"
        android:layout_below="@+id/text_title"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button_dialog_list"
        android:text="List Dialog"
        android:gravity="center"
        android:layout_marginTop="16dp"
        android:padding="16dp"
        android:textSize="20sp"
        android:textColor="#FFFFFF"
        android:background="#D74B4C"
        android:layout_below="@+id/button_dialog_simple" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button_dialog_single_choice"
        android:text="Single Choice Dialog"
        android:gravity="center"
        android:layout_marginTop="16dp"
        android:padding="16dp"
        android:textSize="20sp"
        android:textColor="#FFFFFF"
        android:background="#D74B4C"
        android:layout_below="@+id/button_dialog_list" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button_dialog_multi_choice"
        android:text="Multi Choice Dialog"
        android:gravity="center"
        android:layout_marginTop="16dp"
        android:padding="16dp"
        android:textSize="20sp"
        android:textColor="#FFFFFF"
        android:background="#D74B4C"
        android:layout_below="@+id/button_dialog_single_choice"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button_dialog_custom"
        android:text="Custom Dialog 1"
        android:gravity="center"
        android:layout_marginTop="16dp"
        android:padding="16dp"
        android:textSize="20sp"
        android:textColor="#FFFFFF"
        android:background="#D74B4C"
        android:layout_below="@+id/button_dialog_multi_choice" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button_dialog_custom2"
        android:text="Custom Dialog 2"
        android:gravity="center"
        android:layout_marginTop="16dp"
        android:padding="16dp"
        android:textSize="20sp"
        android:textColor="#FFFFFF"
        android:background="#D74B4C"
        android:layout_below="@+id/button_dialog_custom" />

</RelativeLayout>

custom_dialog.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="64dp"
        android:text="Login"
        android:gravity="center"
        android:textSize="32sp" />
    <EditText
        android:id="@+id/username"
        android:inputType="textEmailAddress"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Username" />
    <EditText
        android:id="@+id/password"
        android:inputType="textPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Password"/>
</LinearLayout>

custom_dialog2.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">
    <EditText
        android:id="@+id/username"
        android:inputType="textEmailAddress"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:layout_marginLeft="4dp"
        android:layout_marginRight="4dp"
        android:layout_marginBottom="4dp"
        android:hint="Username" />
    <EditText
        android:id="@+id/password"
        android:inputType="textPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="4dp"
        android:layout_marginLeft="4dp"
        android:layout_marginRight="4dp"
        android:layout_marginBottom="16dp"
        android:hint="Password"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:weightSum="1">

        <Button
            android:id="@+id/button_cancel"
            android:layout_weight="0.5"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:padding="16dp"
            android:text="Cancel"/>

        <Button
            android:id="@+id/button_login"
            android:layout_weight="0.5"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:padding="16dp"
            android:text="Login"/>
    </LinearLayout>
</LinearLayout>

MainActivity.java

package com.phonbopit.sample.dialog;

import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.util.ArrayList;

public class MainActivity extends ActionBarActivity {

    private Button mSimpleDialog;
    private Button mListDialog;
    private Button mSingleChoiceDialog;
    private Button mMultiChoiceDialog;
    private Button mCustomDialog1;
    private Button mCustomDialog2;

    private static final String[] NAMES = {"KitKat", "Jelly Bean",
            "Ice Cream Sandwich", "Honeycomb", "Gingerbread", "Froyo"};

    private int mIndexSelected;
    private ArrayList<Integer> mMultiSelected;

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

        // Link to all View that declare in activity_main.xml
        mSimpleDialog = (Button) findViewById(R.id.button_dialog_simple);
        mListDialog = (Button) findViewById(R.id.button_dialog_list);
        mSingleChoiceDialog =
                (Button) findViewById(R.id.button_dialog_single_choice);
        mMultiChoiceDialog =
                (Button) findViewById(R.id.button_dialog_multi_choice);
        mCustomDialog1 = (Button) findViewById(R.id.button_dialog_custom);
        mCustomDialog2 = (Button) findViewById(R.id.button_dialog_custom2);

        // Set OnClickListener each button with difference dialog
        mSimpleDialog.setOnClickListener(SimpleDialogOnClick);
        mListDialog.setOnClickListener(ListDialogOnClick);
        mSingleChoiceDialog.setOnClickListener(SingleDialogOnClick);
        mMultiChoiceDialog.setOnClickListener(MultiDialogOnClick);
        mCustomDialog1.setOnClickListener(CustomDialogOnClick);
        mCustomDialog2.setOnClickListener(CustomDialog2OnClick);
    }


    View.OnClickListener SimpleDialogOnClick = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            AlertDialog.Builder builder =
                    new AlertDialog.Builder(MainActivity.this);
            builder.setMessage("Are you ready?");
            builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    Toast.makeText(getApplicationContext(),
                            "OK, Let's go!", Toast.LENGTH_SHORT).show();
                }
            });
            builder.setNegativeButton("No, Thanks", null);
            builder.show();
        }
    };

    View.OnClickListener ListDialogOnClick = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            AlertDialog.Builder builder =
                    new AlertDialog.Builder(MainActivity.this);
            builder.setTitle("Select Your Favorite Name?");
            builder.setItems(NAMES, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    String selected = NAMES[which];
                    Toast.makeText(getApplicationContext(), "Select " +
                            selected, Toast.LENGTH_SHORT).show();
                }
            });
            builder.setNegativeButton("No, Thanks", null);
            builder.show();
        }
    };

    View.OnClickListener SingleDialogOnClick = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            AlertDialog.Builder builder =
                    new AlertDialog.Builder(MainActivity.this);
            builder.setTitle("Select Your Favorite Name?");

            //You need to set default item checked when open Dialog by use mIndexSelected.
            builder.setSingleChoiceItems(NAMES, mIndexSelected, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // store index with you choose in mIndexSelected.
                    mIndexSelected = which;
                }
            });
            builder.setPositiveButton("Confirm", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    Toast.makeText(getApplicationContext(), "Select: " +
                            NAMES[mIndexSelected], Toast.LENGTH_SHORT).show();
                    dialog.dismiss();
                }
            });

            builder.setNegativeButton("No", null);
            builder.show();
        }
    };

    View.OnClickListener MultiDialogOnClick = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mMultiSelected = new ArrayList<Integer>();

            AlertDialog.Builder builder =
                    new AlertDialog.Builder(MainActivity.this);
            builder.setTitle("Select Your Favorite Name?");
            builder.setMultiChoiceItems(NAMES, null, new DialogInterface.OnMultiChoiceClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which, boolean isChecked) {
                    if (isChecked) {
                        mMultiSelected.add(which);
                    } else if (mMultiSelected.contains(which)) {
                        mMultiSelected.remove(Integer.valueOf(which));
                    }
                }
            });

            builder.setPositiveButton("Confirm", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    StringBuffer buffer = new StringBuffer();
                    for (Integer team : mMultiSelected) {
                        buffer.append(" ");
                        buffer.append(NAMES[team]);
                    }
                    Toast.makeText(getApplicationContext(), "Select:" +
                            buffer.toString(), Toast.LENGTH_SHORT).show();
                    dialog.dismiss();
                }
            });

            builder.setNegativeButton("No, Thanks", null);
            builder.show();
        }
    };

    View.OnClickListener CustomDialogOnClick = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            AlertDialog.Builder builder =
                    new AlertDialog.Builder(MainActivity.this);
            LayoutInflater inflater = getLayoutInflater();

            View view = inflater.inflate(R.layout.custom_dialog, null);
            builder.setView(view);

            final EditText username = (EditText) view.findViewById(R.id.username);
            final EditText password = (EditText) view.findViewById(R.id.password);

            builder.setPositiveButton("Login", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // Check username password
                    if (username.getText().equals("[email protected]") &&
                            password.getText().equals("demo")) {
                        Toast.makeText(getApplicationContext(), "Login success!",
                                Toast.LENGTH_SHORT).show();
                    } else {
                        Toast.makeText(getApplicationContext(), "Login Failed!",
                                Toast.LENGTH_SHORT).show();
                    }
                }
            });
            builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {

                }
            });

            builder.show();
        }
    };

    View.OnClickListener CustomDialog2OnClick = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            final Dialog dialog = new Dialog(MainActivity.this);
            dialog.setTitle("Phonbopit Login System");
            dialog.setContentView(R.layout.custom_dialog2);

            final EditText username = (EditText) dialog.findViewById(R.id.username);
            final EditText password = (EditText) dialog.findViewById(R.id.password);
            Button buttonCancel = (Button) dialog.findViewById(R.id.button_cancel);
            Button buttonLogin = (Button) dialog.findViewById(R.id.button_login);

            buttonCancel.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    dialog.dismiss();
                }
            });

            buttonLogin.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    // Check username password
                    if (username.getText().equals("[email protected]") &&
                            password.getText().equals("demo")) {
                        Toast.makeText(getApplicationContext(), "Login success!",
                                Toast.LENGTH_SHORT).show();
                        dialog.dismiss();
                    } else {
                        Toast.makeText(getApplicationContext(), "Login Failed!",
                                Toast.LENGTH_SHORT).show();
                    }
                }
            });
            dialog.show();
        }
    };

}