java - 我如何从 fragment 打开新布局并返回 fragment

Question

我有一个 fragment 有 3 种布局:A.java, B.java, C.java, Newpage.Java, Main.Java

和布局:act_main, act_a, act_b, act_c, act_newpage

我想通过单击按钮从 fragment 创建和打开新布局，然后再次返回 fragment 。我试过了，但没有用。我有什么错？

    //in Main.Java
    public class MainActivity extends AppCompatActivity {
        private Toolbar toolbar;
        private TabLayout tabLayout;
        private ViewPager viewPager;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            viewPager = (ViewPager) findViewById(R.id.viewpager);
            viewPager.setOffscreenPageLimit(3);
            setupViewPager(viewPager);
            tabLayout = (TabLayout) findViewById(R.id.tabs);
            tabLayout.setupWithViewPager(viewPager);
            setupTabIcons();
        }

        private void setupTabIcons() {
            tabOne = (TextView) LayoutInflater.from(this).inflate(R.layout.custom_tab, null);
            tabOne.setText("A");
            tabOne.setCompoundDrawablesWithIntrinsicBounds(0, R.drawable.A_40_negative, 0, 0);
            tabLayout.getTabAt(0).setCustomView(tabOne);

            tabTwo = (TextView) LayoutInflater.from(this).inflate(R.layout.custom_tab, null);
            tabTwo.setText("B");
            tabOne.setCompoundDrawablesWithIntrinsicBounds(0, R.drawable.B_40_negative, 0, 0);
            tabLayout.getTabAt(1).setCustomView(tabTwo);

            tabThree = (TextView) LayoutInflater.from(this).inflate(R.layout.custom_tab, null);
            tabThree.setText("C");
            tabThree.setCompoundDrawablesWithIntrinsicBounds(0, R.drawable.C_40_negative, 0, 0);
            tabLayout.getTabAt(2).setCustomView(tabTwo);
        }

        private void setupViewPager(ViewPager viewPager) {
            ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
            adapter.addFrag(new A(), "A");
            adapter.addFrag(new B(), "B");
            adapter.addFrag(new C(), "C");
            viewPager.setAdapter(adapter);
        }

        class ViewPagerAdapter extends FragmentPagerAdapter {
            private final List<Fragment> mFragmentList = new ArrayList<>();
            private final List<String> mFragmentTitleList = new ArrayList<>();

            public ViewPagerAdapter(FragmentManager manager) {
                super(manager);
            }
            @Override
            public Fragment getItem(int position) {
                return mFragmentList.get(position);
            }
            @Override
            public int getCount() {
                return mFragmentList.size();
            }
            public void addFrag(Fragment fragment, String title) {
                mFragmentList.add(fragment);
                mFragmentTitleList.add(title);
            }
            @Override
            public CharSequence getPageTitle(int position) {
                return mFragmentTitleList.get(position);
            }
        }
    }

    //in A.Java;
    public class A extends Fragment {
        public A() {
        // Required empty public constructor
        }
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
        }
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            View view = inflater.inflate(R.layout.act_A, container, false);

            btnOpenNewLayout.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    Intent intent = new Intent(getActivity(), Newpage.class);
                    startActivity(intent);
                }
            });
            return view;
        }
    }


    //in Newpage.Java;
    public class Newpage extends Fragment{

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

AndroidManifest.xml

    <?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:dist="http://schemas.android.com/apk/distribution"
        package="com.blabla.myapp">
        <dist:module dist:instant="true" />

        <application
            android:allowBackup="true"
            android:icon="@mipmap/ic_launcher"
            android:label="@string/app_name"
            android:supportsRtl="true"
            android:theme="@style/MyMaterialTheme">
            <activity android:name=".MainActivity">
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>
            <activity android:name="Newpage">
            </activity>
        </application>

    </manifest>

error:android.content.ActivityNotFoundException: Unable to find explicit activity class {.......}; have you declared this activity in your AndroidManifest.xml?

我该怎么做？怎么了？感谢您的帮助。

Answer 1

改变

//in Newpage.Java;
public class Newpage extends Fragment{

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

到

//in Newpage.Java;
public class Newpage extends Activity{

    public Newpage() {
    }
    public View onCreate(Bundle savedInstanceState) {
        setContentView(R.layout.act_newpage);
    }
}

要返回上一个 Activity ，您需要在单击按钮时调用 finish()