所以我有一个非常基本的布局,在屏幕的顶部有一个EditText和一个Button。当有人点击按钮时,EditText输入将保存到文本视图中,然后隐藏EditText以及按钮。这是我的代码:
public void setName(View view){
EditText editText = (EditText) findViewById(R.id.getUserName);
Button button = (Button) findViewById(R.id.setName);
TextView textView = (TextView) findViewById(R.id.displayName);
playerName = editText.getText().toString();
textView.setText(playerName);
editText.setVisibility(View.GONE);
button.setVisibility(View.GONE);
textView.setTextSize(40);
textView.setVisibility(View.VISIBLE);
}
当旋转屏幕时,再次调用onCreate,如下所示:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_score_keeper);
// Identifies a textView
TextView textView = (TextView) findViewById(R.id.displayName);
// Hide that textView until later
textView.setVisibility(View.GONE);
// Set player name to default value
playerName = "Player Name";
// Set score to default value
score = 0;
}
这个问题是它丢失了我隐藏EditText和Button的事实,并且还隐藏了TextView。
如何保持所有这些属性相同? (例如,保持文本相同,文本大小,视图的可见性等); 是否可以使用onSaveInstanceState?
谢谢你们。
OSFTW
答案 0 :(得分:5)
你肯定可以在Activity的savedInstanceState上执行此操作,但我也建议(因为这可能是你在多个位置执行的操作)只编写View的子类,这也保存了它作为状态的可见性,例如:
public class VisibiitySaveTextView extends TextView {
//These are just keys to save and restore values from the state
private static final String SUPER_STATE = "super_state";
private static final String VISIBILITY = "visibility";
//Constructors
@Override
public Parcelable onSaveInstanceState () {
Bundle state = new Bundle();
//Piggyback off of the View's implementation and store that
//bundle of saved information in our container bundle
state.putParcelable(SUPER_STATE, super.onSaveInstanceState());
//Store the current visibility of the View in the saved state
state.putInt(VISIBILITY, getVisibility());
return state;
}
@Override
public void onRestoreInstanceState (Parcelable state) {
//state should always be an instance of Bundle since that's what
//we're saving, but check for safety
if (state instanceof Bundle) {
Bundle savedState = (Bundle)state;
//Set the visibility of the View to match the visibility that
//we retained in onSavedInstanceState(), falling back to the
//current visibility as default if no state was saved
setVisibility(savedState.getInt(VISIBILITY, getVisibility()));
//Pull out the superclass state we saved, and let the superclass
//handle restoring all of the other state
Parcelable superState = savedState.getParcelable(SUPER_STATE);
super.onRestoreInstanceState(superState);
} else {
//Nothing special to do here other than pass it up to the super
super.onRestoreInstanceState(state);
}
}
}
编辑:让Activity处理状态的示例:
private static final String MY_EDIT_TEXT_VISIBILITY = "my_edit_text_visibility";
private static final String MY_TEXT_VIEW_VISIBILITY - "my_text_view_visibility";
private static final String MY_BUTTON_VISIBILITY - "my_button_visibility";
@Override
protected void onSaveInstanceState (Bundle outState) {
super.onSaveInstanceState(outState);
//Save the state of each of these. It's super important to add null checks here
//(which is why I prefer to let the View handle it) as in some cases this can
//get called after the Views have been destroyed.
if (myEditText != null) {
outState.putInt(MY_EDIT_TEXT_VISIBILITY, myEditText.getVisibility());
}
if (myTextView != null) {
outState.putInt(MY_TEXT_VIEW_VISIBILITY, myTextView.getVisibility());
}
if (myButton != null) {
outState.putInt(MY_BUTTON_VISIBILITY, myButton.getVisibility());
}
}
@Override
protected void onRestoreInstanceState (Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
//Check if we have saved state, and restore the visibility
//to all of the Views we care about
if (savedInstanceState != null) {
myEditText.setVisibility(savedInstanceState.getInt(MY_EDIT_TEXT_VISIBILITY, myEditText.getVisibility()));
myTextView.setVisibility(savedInstanceState.getInt(MY_TEXT_VIEW_VISIBILITY, myTextView.getVisibility()));
myButton.setVisibility(savedInstanceState.getInt(MY_BUTTON_VISIBILITY, myButton.getVisibility()));
}
}
答案 1 :(得分:0)
覆盖:
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState)
{
super.onRestoreInstanceState(savedInstanceState);
if (button not visible)
savedInstanceState.putBoolean("Visibility", false);
savedInstanceState.putString("text", "EditView text");
}
on onCreate:
if (savedInstanceState != null) {
boolean x = savedInstanceState.getBoolean("visibility");
String s = savedInstanceState.getString("text");
// set values
}