Android Tutorial #1 Handler Description

Main Activity






package com.aabit.handler;
import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.os.Handler;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    EditText un,pwd;
    Button login;

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

        init();
    }

    private void init(){
        un=(EditText)findViewById(R.id.un);
        pwd=(EditText)findViewById(R.id.pwd);
        login=(Button)findViewById(R.id.login);

        login.setOnClickListener(new View.OnClickListener() {
            @Override            public void onClick(View v) {

                new ThreadLogin(un.getText().toString(),pwd.getText().toString(),new myHandler()).execute((Object[])null);
            }
        });
    }


    private class myHandler extends Handler {
        @Override        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            boolean status=(boolean)msg.obj;
            if(status){
                Toast.makeText(getApplicationContext(),"Good",Toast.LENGTH_LONG).show();
            }
            else{
                Toast.makeText(getApplicationContext(),"Bad",Toast.LENGTH_LONG).show();
            }
        }
    }

}








ThreadLogin.class


package com.aabit.handler;

import android.os.AsyncTask;
import android.os.Message;
import android.os.Handler;
import android.text.Editable;

/** * Created by aabit on 2/27/16. */public class ThreadLogin extends AsyncTask<Object,Object,Boolean> {

    String uname;
    String pwd;
    Handler myHandler;

    public ThreadLogin(String uname, String pwd, Handler myHandler) {
        this.uname = uname;
        this.pwd = pwd;
        this.myHandler = myHandler;
    }

    @Override    protected Boolean doInBackground(Object... params) {
        if(this.uname.equals(this.pwd))
            return true;
        else            return false;
    }

    @Override    protected void onProgressUpdate(Object... values) {
        super.onProgressUpdate(values);
    }

    @Override    protected void onPostExecute(Boolean aBoolean) {
        super.onPostExecute(aBoolean);
        Message msg = new Message();
        msg.obj = aBoolean;
        myHandler.sendMessage(msg);
    }

    @Override    protected void onPreExecute() {
        super.onPreExecute();
    }
}


Layout 

Activity_main

<?xml version="1.0" encoding="utf-8"?><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"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.aabit.handler.MainActivity">


    <LinearLayout        android:orientation="vertical"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true"        android:layout_marginTop="160dp"        android:padding="20dp">

        <EditText            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:inputType="textPersonName"            android:text="Name"            android:ems="10"            android:id="@+id/un"            android:layout_gravity="center" />

        <EditText            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:inputType="textPassword"            android:ems="10"            android:id="@+id/pwd"            android:layout_gravity="center" />

        <Button            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:text="New Button"            android:id="@+id/login"            android:layout_gravity="center_horizontal" />
    </LinearLayout>
</RelativeLayout>