To save instance state, override onSaveInstanceState() method to put it in outState. Then retrieve it in onCreate(). And override onPrepareOptionsMenu() method to set Visible of menu items accordingly.
Modify MainActivity.java in last exercise.
package com.example.androidmenu;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.Toast;
import android.widget.ToggleButton;
public class MainActivity extends Activity {
Menu menu;
ToggleButton toggleButtonUp, toggleButtonDown;
Boolean savedMenuUpIsVisible, savedMenuDownIsVisible;
final static String KEY_Menu_Up = "KEY_MENU_UP";
final static String KEY_Menu_Down = "KEY_MENU_DOWN";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toggleButtonUp = (ToggleButton)findViewById(R.id.buttonup);
toggleButtonDown = (ToggleButton)findViewById(R.id.buttondown);
toggleButtonUp.setOnCheckedChangeListener(new OnCheckedChangeListener(){
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if(menu != null){
MenuItem item_up = menu.findItem(R.id.action_up);
item_up.setVisible(isChecked);
}
}});
toggleButtonDown.setOnCheckedChangeListener(new OnCheckedChangeListener(){
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (menu != null){
MenuItem item_down = menu.findItem(R.id.action_down);
item_down.setVisible(isChecked);
}
}});
if(savedInstanceState != null){
savedMenuUpIsVisible = savedInstanceState.getBoolean(KEY_Menu_Up, true);
savedMenuDownIsVisible = savedInstanceState.getBoolean(KEY_Menu_Down, true);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
this.menu = menu;
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()){
case R.id.action_settings:
Toast.makeText(getApplicationContext(),
"Setting...",
Toast.LENGTH_SHORT).show();
break;
case R.id.action_up:
Toast.makeText(getApplicationContext(),
"Up...",
Toast.LENGTH_SHORT).show();
break;
case R.id.action_down:
Toast.makeText(getApplicationContext(),
"Down...",
Toast.LENGTH_SHORT).show();
break;
case R.id.action_other:
Toast.makeText(getApplicationContext(),
"Other...",
Toast.LENGTH_SHORT).show();
break;
default:
Toast.makeText(getApplicationContext(),
"Unknown...",
Toast.LENGTH_SHORT).show();
break;
}
//Return false to allow normal menu processing to proceed,
//true to consume it here.
return false;
}
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
if(savedMenuUpIsVisible != null){
MenuItem item_up = menu.findItem(R.id.action_up);
item_up.setVisible(savedMenuUpIsVisible);
}
if(savedMenuDownIsVisible != null){
MenuItem item_down = menu.findItem(R.id.action_down);
item_down.setVisible(savedMenuDownIsVisible);
}
return super.onPrepareOptionsMenu(menu);
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
if (menu != null){
MenuItem item_up = menu.findItem(R.id.action_up);
outState.putBoolean(KEY_Menu_Up, item_up.isVisible());
MenuItem item_down = menu.findItem(R.id.action_down);
outState.putBoolean(KEY_Menu_Down, item_down.isVisible());
}
}
}
Download the files.
0 comments:
Post a Comment