package com.example.helloworld;

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;

public class MainActivity extends Activity
{
    private Button button;
 @Override
 protected void onCreate(Bundle savedInstanceState)
 {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  
     this.button = (Button) this.findViewById(R.id.button1);
         this.button.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View v) {
                 Intent intent = new Intent();
                 intent.setClass(MainActivity.this, IntentActivity.class);
                 intent.putExtra("name", "Hello World");
                 startActivity(intent);
             }
         }); 
 } 
}

<activity
   android:name="com.example.helloworld.IntentActivity"> </activity>

package com.example.helloworld;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
import android.content.Intent;
public class IntentActivity extends Activity
{
 @Override
 protected void onCreate(Bundle savedInstanceState)
 {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_intent);
  Intent intent = getIntent();
  String string = intent.getStringExtra("name");

  TextView textView = new TextView(this);
  textView.setTextSize(40);
  textView.setText(string);
  
  setContentView(textView);
 }
}