Android学习笔记（十一）——将Fragment添加到Activity中以及参数传递

将Fragment添加到Activity中

Fragment的布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center">
    <TextView
        android:id="@+id/tv_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="#000"
        android:text="我是AFragment"
        android:textSize="20sp"
        android:gravity="center"/>

</LinearLayout>

Activity的布局文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"
    android:layout_height="match_parent"
>
    <Button
        android:id="@+id/btn_change"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="更换fragment"
        />
    <FrameLayout                                            //用于放置Fragment
        android:id="@+id/fl_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@+id/btn_change"/>
</RelativeLayout>

将这个AFragment添加到Activity中去，通过Activity中的java代码

private AFragment mAFragment;
 //实例化AFragment
 mAFragment=new AFragment();
 //将AFragment添加到activity中去,记得调用commit
getSupportFragmentManager()beginTransaction().add(R.id.fl_container,mAFragment).commitAllowingStateLoss();

效果显示：

点击按钮将AFragment切换成BFragment

 mbtnChange=(Button)findViewById(R.id.btn_change);
        mbtnChange.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(mBFragment==null){
                    mBFragment=new BFragment();
                }
                getSupportFragmentManager().beginTransaction().replace(R.id.fl_container,mBFragment).commitAllowingStateLoss();    //这里将add方法换成replace方法
            }
        });

效果展示：

参数传递——通过setArguements（）

注意：不能直接写一个带参数的构造函数来传递参数

在AFragment中的java代码：

public class AFragment extends Fragment {
    private TextView mTvtitle;
  //  private Activity mActivity;

    public static AFragment setInstance(String title){   //Fragment传递参数
        AFragment afragment=new AFragment();
        Bundle bundle=new Bundle();
        bundle.putString("title",title);
        afragment.setArguments(bundle);
        return afragment;
    }
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view =inflater.inflate(R.layout.fragment_a,container,false);   //找到布局文件
        //return super.onCreateView(inflater, container, savedInstanceState);
        return view;
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        mTvtitle=(TextView)view.findViewById(R.id.tv_title);   //找到组件
        if(getArguments()!=null){
            mTvtitle.setText(getArguments().getString("title"));   //得到传递的参数
        }
    }
    }

在Activity的java代码中：

mAFragment=AFragment.setInstance("我是参数");    //通过setInstance设置参数

//将AFragment添加到activity中去,记得调用commit
        getSupportFragmentManager().beginTransaction().add(R.id.fl_container,mAFragment).commitAllowingStateLoss();

效果显示：