Android中Fragment的动态加载和双屏切换问题

步骤：1、在Activity布局文件中定义framelayout用于添加Fragment2、创建两个Fragment用于切换3、获取Fragment管理器，并开启事物FragmentTransaction4、通FragmentTransaction.add(resource id, fragment)将fragment添加到布局上，提交事物commit5、通FragmentTransaction. replace(resource id, fragment)切换显示的fragment，提交事物commit

acvitity_dynamic.xml <Button        android:id="@+id/btn_change"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="切换" />    <FrameLayout        android:id="@+id/fl_fragment"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:background="@android:color/holo_green_light"></FrameLayout>

DynamicAcvitity.javapublic class DynamicActivity extends AppCompatActivity {    private Button btn_change;    private BlankFragment blank;    private SecFragment sec;    private Fragment fragment;//用该变量表示现在展示的是哪一个fragment    private FragmentManager manager;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_dynamic);        blank = new BlankFragment();        sec = new SecFragment();        fragment=blank;        manager=getSupportFragmentManager();        //开始一个事物        FragmentTransaction transaction=manager.beginTransaction();        transaction.add(R.id.fl_fragment,blank);        transaction.commit();//事物要提交过后才会有效        //实例化按钮        btn_change= (Button) findViewById(R.id.btn_change);        btn_change.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                //一个事物提交后结束不能再用，要新建一个事物                FragmentTransaction transaction1=manager.beginTransaction();                if(fragment instanceof BlankFragment){                        fragment=sec;                }else {                    fragment=blank;                }                transaction1.replace(R.id.fl_fragment,fragment);                transaction1.commit();            }        });