Android Examples : example 1

creating app for sending and receiving data from one activity to another:

MainActivity.java
package com.example.sample;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

EditText et1;
EditText et2;

Button b;

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

et1= (EditText) findViewById(R.id.uname);
et2= (EditText) findViewById(R.id.pwd);
b= (Button)findViewById(R.id.sub);
b.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
String str1=et1.getText().toString();
String str2=et2.getText().toString();

if (str1.equals("admin") && str2.equals("admin"))
{
Intent in= new Intent(getApplicationContext(),sample.class);
in.putExtra("username", str1);

startActivity(in);
}
if(str1.equals("")&& str2.equals(""))
Toast.makeText(getApplicationContext(), "Please Enter Username & Password", 200).show();

}
});

}
}

sample.java

package com.example.sample;

import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

import android.widget.EditText;

import android.widget.TextView;

import android.widget.Toast;

public class sample extends Activity

{

EditText et1;

EditText et2;

public void onCreate(Bundle b)

{

super.onCreate(b);

//setContentView(R.layout.one);

//Intent i=new Intent(sample.class,MainActivity.this);

// et1=(EditText) findViewById(R.id.uname);

// et2=(EditText) findViewById(R.id.pwd);

//Intent i=new Intent("username",this);

String str= getIntent().getExtras().getString("username");

Toast.makeText(getApplicationContext(), str, 500).show();

TextView tv=new TextView(getApplicationContext());

tv.setText("welcome"+str);

setContentView(tv);

}

activity_main.xml

<LinearLayout 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=".MainActivity"

android:orientation="vertical">

<ImageView

android:id="@+id/img1"

android:layout_width="wrap_content"