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

  <LinearLayout
      android:id="@+id/main"
      android:layout_width="match_parent"
      android:layout_height="0dp"
      android:layout_weight="1"
      android:orientation="horizontal">

  </LinearLayout>
<Button
    android:id="@+id/btn_main"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="onClick"
    android:background="#000000"
    android:textColor="#0000ff"
    android:text="点击"
    android:textSize="30sp"
    />

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

<LinearLayout
    android:id="@+id/second"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1"
    android:orientation="horizontal"
    >

</LinearLayout>
<TextView
    android:gravity="center"
    android:id="@+id/btn_two"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#000000"
    android:textColor="#ffffff"
    android:text="这是第一个Fragment"
    android:textSize="20sp"/>

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;
}
 }

posted @ 2017-04-18 20:40  yeech  阅读(142)  评论(0编辑  收藏  举报