Android开发 保存Activity的状态值

切换activity时对已输入的数据进行保存, 当返回到当前界面时, 数据可以保存下来
话不多说, 直接上代码

/**
*当界面临时切换出去是, 即调用onPause方法时, 该方法被调用
*/
public class MainActivity extends Activity {
	private final static String TAG = "MainActivity";
	private static final String CONTENT = "content";
	private Button secondBtn = null;
	private EditText txt = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		txt = (EditText) findViewById(R.id.txt);//获取输入框对象
		if (null != savedInstanceState && savedInstanceState.containsKey(CONTENT)) {
			txt.setText(savedInstanceState.getString(CONTENT));//再次回到该界面时, 对值进行恢复
		}
		secondBtn = (Button) findViewById(R.id.secondBtn);
		secondBtn.setOnClickListener(listener);
		Log.i(TAG, "MainActivity-->onCreate");
	}
	/**
	 * 当main_activity执行onPause方法时,也就是切换页面到其他界面,此时使用该方法对输入框数据进行保存
	 */
	@Override
	//Bundle对象类似于java.util.Map,以键值对的形式存储数据
	protected void onSaveInstanceState(Bundle outState) {
		super.onSaveInstanceState(outState);
		Log.i(TAG, "MainActivity-->onSaveInstanceState");
		String content = txt.getText().toString();
		outState.putString(CONTENT, content);//存储数据到Bundle
	}
}

至此 问题完美解决