如何在 onCreate 中打开一个随机片段进行活动？

Question

我想在启动 MainAcitivity 时在我的框架布局中打开一个随机片段。

问题：

1. 如何将 random1 值转换为片段？

2. 按下屏幕上的按钮时是否很难“刷新”视图以获取另一个随机片段？

   public class Beginner extends ActionBarActivity {
   
   private SoundPool spool;
   public int soundID_R1;
   public int soundID_R5;
   public int soundID_R8;
   
   private Fragment_gehorINTbeginnerR1 intBegFragment_R1;
   private Fragment_gehorINTbeginnerR5 intBegFragment_R5;
   private Fragment_gehorINTbeginnerR8 intBegFragment_R8;
   private int randomFragmentNum;
   private FrameLayout container;
   private FragmentTransaction fragmentTransaction;
   
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.fragment_beginner);
   
       initUI();
   }
   
   private void initUI() {
       container = (FrameLayout) findViewById(R.id.beginner_frame);
       fragmentTransaction = getSupportFragmentManager().beginTransaction();
       setRandomFragment();
   }
   
   private void setRandomFragment() {
       Random random = new Random();
       randomFragmentNum = random.nextInt(2);
       //random choose fragment
       switch (randomFragmentNum) {
           case 0: {
               intBegFragment_R1 = new Fragment_gehorINTbeginnerR1();
               fragmentTransaction.replace(R.id.beginner_frame, intBegFragment_R1);
               fragmentTransaction.commit();
               break;
           }
           case 1: {
               intBegFragment_R5 = new Fragment_gehorINTbeginnerR5();
               fragmentTransaction.replace(R.id.beginner_frame, intBegFragment_R5);
               fragmentTransaction.commit();
               break;
           }
           case 2: {
               intBegFragment_R8 = new Fragment_gehorINTbeginnerR8();
               fragmentTransaction.replace(R.id.beginner_frame, intBegFragment_R8);
               fragmentTransaction.commit();
               break;
           }
       }
   }
   

Answer 1

这是一个例子：

   switch(random1.nextInt(3)){
        case 0:  setMyFragment(new Fragment_gehorINTbeginnerR1());
                 break;
        case 1: setMyFragment(new Fragment_gehorINTbeginnerR5());
                break;
        case 2: setMyFragment(new Fragment_gehorINTbeginnerR8());
                break;
    }

我使用一种方法来加载我的片段：

 public void setMyFragment(Fragment fr){
    try{
        FragmentManager fm = getSupportFragmentManager();
        if(fr != null){
            FragmentTransaction ft = fm.beginTransaction();
            ft.replace(R.id.Mainfragment, fr, null);
                            ft.commitAllowingStateLoss();
        }
    }catch(IllegalStateException e) {           
        Log.e(TAG, "ISE setting main view "+e.getMessage());
    }       
}

Answer 2

简单的解决方案（更新 2）。如果使用 2 个随机片段，则必须在 random.getInt() 中设置值 100，如果三个片段 - 150，四个 - 200...并添加块 if-else 用于逻辑选择片段：

 /**
     * Created by scijoker on 2/14/14.
     */
    public class TestRandomFragmentActivity extends FragmentActivity {
        private LoginFragment loginFragment;
        private SignUpFragment signUpFragment;
        private FragmentTransaction fragmentTransaction;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.access_activity);

            initUI();
        }

        private void initUI() {
            fragmentTransaction = getSupportFragmentManager().openTransaction();
            setRandomFragment();
        }

        private void setRandomFragment() {
            Random random = new Random();
           int randomFragmentNum = random.nextInt(100);
        if (randomFragmentNum < 50) {
            randomFragmentNum = 0;
        } else{
            randomFragmentNum = 1;
        }
            //random choose fragment
            switch (randomFragmentNum) {
                case 0: {
                    loginFragment = new LoginFragment();
                    fragmentTransaction.add(R.id.fl_container, loginFragment);
                    fragmentTransaction.commit()
                    break;
                }
                case 1: {
                    signUpFragment = new SignUpFragment();
                    fragmentTransaction.add(R.id.fl_container, signUpFragment);
                    fragmentTransaction.commit()
                    break;
                }
            }
        }

Answer 3

问题是随机的：在三个片段之间进行随机选择的参数非常小。这段代码可以帮助你。请插入 setRandomFragment():

randomFragmentNum = random.nextInt(150);
        if (randomFragmentNum < 50) {
            randomFragmentNum = 0;
        } else if (randomFragmentNum < 100) {
            randomFragmentNum = 1;
        } else randomFragmentNum = 2;

更新 2： 对于五个片段

randomFragmentNum = random.nextInt(250);
            if (randomFragmentNum < 50) {
                randomFragmentNum = 0;
            } else if (randomFragmentNum < 100) {
                randomFragmentNum = 1;
            } else if (randomFragmentNum < 150) {
                randomFragmentNum = 2;
            } else if (randomFragmentNum < 200) {
                randomFragmentNum = 3;
            } else 
                randomFragmentNum = 4;
            }