Changing Activity in Android

In Android, a new page(html) is a new screen and thus is a new Activity, for example you have an application that has a preferences screen and you want to open that preferences on your application, here is how to do it.

Quick background, here we have 2 Activity classes, Main and Preferences, each activity has its own layout xml. I shall provide only the core code to do this and add a link to the other files that is required for this article.
package com.monmonja.firstDemo;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class Main extends Activity implements View.OnClickListener{
  private View preferencesBtn;
  @Override
  public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.main);
    this.preferencesBtn = (Button) this.findViewById(R.id.preferencesBtn);
    this.preferencesBtn.setOnClickListener(this);
  }

  public void onClick(View view) {
    if(view == this.preferencesBtn){
      Intent prefIntent = new Intent(this,Preferences.class);
      this.startActivity(prefIntent);
    }
  }
}


Quick Explanation
We set up a button to listen to a click event, and on that event we create a new Intent with Intent prefIntent = new Intent(this,Preferences.class);, where we pass the class name of Preferences, then we use this.startActivity(prefIntent); to start our new Activity. You can take a look at our Preferences.java and Preferences.xml to see that the results. When we're on the Preferences Screen you can hit the back button to go back to the Main Screen.

[gallery]
Preferences.xml Chaging Activity In Android
Main.xml Chaging Activity In Android
Preferences.java Chaging Activity In Android
Main.java Chaging Activity In Android