SharedPreferencesActivity.java

package com.google.mcommerce.sample.android.chapter07.preferences;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

import com.google.mcommerce.sample.android.R;

/**
 * Entry into our redirection example, describing what will happen.
 */
public class SharedPreferencesActivity extends Activity {
	static final int INIT_TEXT_REQUEST = 0;
	static final int NEW_TEXT_REQUEST = 1;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);

		setContentView(R.layout.c07_redirect_main);

		// Watch for button clicks.
		Button clearButton = (Button) findViewById(R.id.clear);
		clearButton.setOnClickListener(mClearListener);
		Button newButton = (Button) findViewById(R.id.newView);
		newButton.setOnClickListener(mNewListener);

		// Retrieve the current text preference. If there is no text
		// preference set, we need to get it from the user by invoking the
		// activity that retrieves it. To do this cleanly, we will
		// temporarily hide our own activity so it is not displayed until the
		// result is returned.
		if (!loadPrefs()) {
			Intent intent = new Intent(this, SharedPreferencesGetter.class);
			startActivityForResult(intent, INIT_TEXT_REQUEST);
		}
	}

	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		if (requestCode == INIT_TEXT_REQUEST) {

			// If the request was cancelled, then we are cancelled as well.
			if (resultCode == RESULT_CANCELED) {
				finish();

				// Otherwise, there now should be text... reload the prefs,
				// and show our UI. (Optionally we could verify that the text
				// is now set and exit if it isn't.)
			} else {
				loadPrefs();
			}

		} else if (requestCode == NEW_TEXT_REQUEST) {

			// In this case we are just changing the text, so if it was
			// cancelled then we can leave things as-is.
			if (resultCode != RESULT_CANCELED) {
				loadPrefs();
			}

		}
	}

	private final boolean loadPrefs() {
		// Retrieve the current redirect values.
		// NOTE: because this preference is shared between multiple
		// activities, you must be careful about when you read or write
		// it in order to keep from stepping on yourself.
		SharedPreferences preferences = getSharedPreferences("RedirectData", 0);

		mTextPref = preferences.getString("text", null);
		if (mTextPref != null) {
			TextView text = (TextView) findViewById(R.id.text);
			text.setText(mTextPref);
			return true;
		}

		return false;
	}

	private OnClickListener mClearListener = new OnClickListener() {
		public void onClick(View v) {
			// Erase the preferences and exit!
			SharedPreferences preferences = getSharedPreferences(
					"RedirectData", 0);
			preferences.edit().remove("text").commit();
			finish();
		}
	};

	private OnClickListener mNewListener = new OnClickListener() {
		public void onClick(View v) {
			// Retrieve new text preferences.
			Intent intent = new Intent(SharedPreferencesActivity.this,
					SharedPreferencesGetter.class);
			startActivityForResult(intent, NEW_TEXT_REQUEST);
		}
	};

	private String mTextPref;
}