How to Handle Back button in android

In this example we will explain how to handle/detect android Mobile Back Button in android programmatically.

/*This allows the system to properly navigate backward when the user presses the Back button.              However, there are a few cases in which your app should manually specify the Back behavior
   in order to provide*/

MainActivity.java
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package com.androidbeginner.testcode;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.widget.Toast;

@SuppressLint("ResourceAsColor")
public class MainActivity extends Activity {

@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getActionBar().setTitle("Used Back Button");
setContentView(R.layout.activity_main);

}

@Override
public void onBackPressed() {
Toast.makeText(getApplicationContext(), "On press Button :--Open PreviousActivity",   Toast.LENGTH_LONG).show();
super.onBackPressed();
}
}

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Back Button Navigation for fragment.

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getSupportFragmentManager().beginTransaction()
    .add(detailFragment, "detail")
    // Add this transaction to the back stack
    .addToBackStack()
    .commit();
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Back Button Navigation for webview.

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@Override
public void onBackPressed() {
   if (mWebView.canGoBack()) {
       mWebView.goBack();
       return;
   }

   // Otherwise defer to system default behavior.
   super.onBackPressed();
}
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