[移动开发]Android Fragment的使用

Android Fragment的使用

实现效果:

项目目录:

具体代码:

容器, 必须是一个Activity, 在这里是主类

public class MainActivity extends AppCompatActivity {

    Button btnA;
    Button btnB;
    Button btnC;

    //直接在创建属性的阶段就使用new对象的方式实例化三个fragment对象
    FragmentA fragmentA = new FragmentA();
    FragmentB fragmentB = new FragmentB();
    FragmentC fragmentC = new FragmentC();

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

        //通过id将三个路由button实例化到本类中
        btnA = findViewById(R.id.btnA);
        btnB = findViewById(R.id.btnB);
        btnC = findViewById(R.id.btnC);

        //在打开应用的时候直接显示fragmentA显示的内容
        getSupportFragmentManager().
                beginTransaction().
                add(R.id.FrameLayout,fragmentA).
                commitAllowingStateLoss();

        //按钮A点击监听: 点击按钮A就跳转至FragmentA
        btnA.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                getSupportFragmentManager().
                        beginTransaction().
                        replace(R.id.FrameLayout, fragmentA).
                        commitAllowingStateLoss();
            }
        });

        //按钮B点击监听: 点击按钮B就跳转至FragmentB
        btnB.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                getSupportFragmentManager().
                        beginTransaction().
                        replace(R.id.FrameLayout, fragmentB).
                        commitAllowingStateLoss();
            }
        });

        //按钮C点击监听: 点击按钮C就跳转至FragmentC
        btnC.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                getSupportFragmentManager().
                        beginTransaction().
                        replace(R.id.FrameLayout, fragmentC).
                        commitAllowingStateLoss();
            }
        });

    }

}

其对应的 容器layout布局

activity_main.xml

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <FrameLayout
            android:id="@+id/FrameLayout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_above="@+id/LinearLayout1"/>

        <TableLayout
            android:id="@+id/LinearLayout1"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:stretchColumns="*"
            android:padding="3dip"
            android:layout_alignParentBottom="true">
            <TableRow>
                <Button
                    android:id="@+id/btnA"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="A"
                    android:paddingTop="10sp"
                    android:paddingBottom="10sp"/>
                <Button
                    android:id="@+id/btnB"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="B"
                    android:paddingTop="10sp"
                    android:paddingBottom="10sp"/>
                <Button
                    android:id="@+id/btnC"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="C"
                    android:paddingTop="10sp"
                    android:paddingBottom="10sp"/>
            </TableRow>
        </TableLayout>

    </RelativeLayout>

</LinearLayout>

FragmentA的布局:

<TextView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="Fragment A"
    android:textAlignment="center"
    android:layout_gravity="center"
    android:gravity="center"
    android:textColor="#000000"
    android:textSize="50sp"/>

FragmentA的代码, 无需是Activity, 但必须继承Fragment:

//类必须 extends Fragment, 并重写下面两个方法
public class FragmentA extends Fragment {

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle saveInstanceState){
        //R.layout.fragment_a 这个是FragmentA对应的layout界面
        return inflater.inflate(R.layout.fragment_a, container, false);
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle saveInstanceState){
        super.onViewCreated(view,saveInstanceState);
    }

}

FragmentB的布局:

<TextView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="Fragment B"
    android:textAlignment="center"
    android:layout_gravity="center"
    android:gravity="center"
    android:textColor="#2196F3"
    android:textSize="50sp"/>

FragmentB的代码, 无需是Activity, 必须继承Fragment:

//类必须 extends Fragment, 并重写下面两个方法
public class FragmentB extends Fragment {

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle saveInstanceState){
        //R.layout.fragment_b 这个是FragmentB对应的layout界面
        return inflater.inflate(R.layout.fragment_b, container, false);
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle saveInstanceState){
        super.onViewCreated(view,saveInstanceState);
    }

}

FragmentC的布局:

<TextView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="Fragment C"
    android:textAlignment="center"
    android:layout_gravity="center"
    android:gravity="center"
    android:textColor="#4CAF50"
    android:textSize="50sp"/>

FragmentC的代码, 无需是Activity, 必须继承Fragment:

public class FragmentC extends Fragment {

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle saveInstanceState){
        //R.layout.fragment_c 这个是FragmentC对应的layout界面
        return inflater.inflate(R.layout.fragment_c, container, false);
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle saveInstanceState){
        super.onViewCreated(view,saveInstanceState);
    }
}