4.14作业

4.14作业

看题目看了半天，才明白是怎么回事。。。要创几个布局。。。

用了动态方法创建Fragment。。。

由题意可知，创建了三个界面，一个主界面，两个Fragment界面

首先来看一下主界面的重要布局代码

以及两个Fragment界面，两个界面布局一样，很简单，一下是主要的布局代码

最大头的就是主界面的Java代码了！！！

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private Fragment blankFragment;
private Fragment secondFragment;
private boolean skip = true;
private boolean exit = false;

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

blankFragment = new BlankFragment();
FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.add(R.id.main, blankFragment);
transaction.commit();
}

public void onClick(View view) {
switch (view.getId()) {
case R.id.btn_main:
jump();
break;
}
}

private void jump() {
boolean exit = true;

if (skip) {
FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
if (secondFragment == null) {
secondFragment = new SecondFragment();
transaction.replace(R.id.main, secondFragment);
transaction.commit();
skip = false;
} else {
transaction.replace(R.id.main, secondFragment);
transaction.commit();
skip = false;
}
} else {
Toast.makeText(this, "这是第二个Fragment", Toast.LENGTH_LONG).show();
}
}

public boolean onKeyDown(int keyCode, KeyEvent event) {

if (event.getKeyCode() == KeyEvent.KEYCODE_BACK && exit) {

FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
skip = true;
exit = false;
transaction.replace(R.id.main, blankFragment);
transaction.commit();
return false;
} else {
finish();
}
return super.onKeyDown(keyCode, event);

}
}

当然了，两个Fragment布局的Java代码也要有所改变，以下

public class SecondFragment extends Fragment {

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
View view = inflater.inflate(R.layout.fragment_second,container,false);
return view;
}
}