1、引用string.xml中的字符串

1) 代碼中 R.string.hello_world

2) XML中@string/hello_world

2、AndroidManifest

android:label指定Activity中標(biāo)題欄的內(nèi)容、也是應(yīng)用程序的名稱(chēng)。

intent-filter中的

標(biāo)識(shí)MainActivity是應(yīng)用的主程序。

3、Toast duration

Toast.LENGTH_SHORT//2S
Toast.LENGTH_LONG//3.5s

4、在Activity中使用Menu
重寫(xiě)onCreateOptionsMenu()

@Override
	public?boolean?onCreateOptionsMenu(Menu?menu)?{
		//?Inflate?the?menu;?this?adds?items?to?the?action?bar?if?it?is?present.
		getMenuInflater().inflate(R.menu.main,?menu);
		return?true;//表示允許將菜單顯示出來(lái)
	}

重寫(xiě) onOptionsItemSelected()

@Override
	public?boolean?onOptionsItemSelected(MenuItem?item)?{
		//?Handle?action?bar?item?clicks?here.?The?action?bar?will
		//?automatically?handle?clicks?on?the?Home/Up?button,?so?long
		//?as?you?specify?a?parent?activity?in?AndroidManifest.xml.
		int?id?=?item.getItemId();
		switch(id){
		case?R.id.add_item:
			Toast.makeText(this,?"add",?Toast.LENGTH_SHORT).show();
			break;
		case?R.id.remove_item:
			Toast.makeText(this,?"remove",?Toast.LENGTH_SHORT).show();
			break;
			default:
		}