Android 持久状态

当你编辑某Text视图时可能会打断当前编辑切换到另外的活动中，如果要持久你的编辑状态那么应该在Activity.onPause（）里面做文章，  例如：

@Override
protected void onPause() {
    super.onPause();
    SharedPreferences.Editor editor = getPreferences(0).edit();
    editor.putString("text", mSavedEditText.getText().toString());
    editor.putInt("selection-start", mSavedEditText.getSelectionStart());
    editor.putInt("selection-end", mSavedEditText.getSelectionEnd());
    editor.commit();
}

当试图重新获得焦点时 需在Activity.onResume中操作 如下：

@Override
    protected void onResume() {
        super.onResume();
        SharedPreferences prefs = getPreferences(0); 
        String restoredText = prefs.getString("text", null);
        if (restoredText != null) {
            mSavedEditText.setText(restoredText, TextView.BufferType.EDITABLE);

            int selectionStart = prefs.getInt("selection-start", -1);
            int selectionEnd = prefs.getInt("selection-end", -1);
            if (selectionStart != -1 && selectionEnd != -1) {
                mSavedEditText.setSelection(selectionStart, selectionEnd);
            }
        }
    }