java - 在 ViewPager 中选择要开始的 fragment - Android

Question

我正在尝试制作一个登录屏幕，其中注册、登录和忘记密码屏幕都是 fragment ，放置如下:

忘记密码 |登入 |注册

我在 YouTube 上找到了一个向我展示如何执行此操作的简单视频。我遇到的唯一问题是，当我启动 Activity 时，它会在忘记密码 fragment 上打开，因为它是第一个 fragment ，但我希望它从中间开始，即登录 fragment 。这是主要 Activity 的代码。我应该更改或添加到此代码中，还是我采用了错误的方法来实现我想要实现的目标

访问.java

public class Access extends FragmentActivity {

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

        initializePaging();
    }

    private void initializePaging() {
        List<Fragment> fragments = new Vector<>();
        fragments.add(Fragment.instantiate(this, AccessForgotPassword.class.getName()));
        fragments.add(Fragment.instantiate(this, AccessLogin.class.getName()));
        fragments.add(Fragment.instantiate(this, AccessRegister.class.getName()));

        PagerAdapter mPagerAdapter = new PagerAdapter(this.getSupportFragmentManager(), fragments);

        ViewPager accessViewPager = (ViewPager) findViewById(R.id.accessViewPager);
        accessViewPager.setAdapter(mPagerAdapter);
    }

}

访问.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/accessMainLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".access.Access">

    <android.support.v4.view.ViewPager
        android:id="@+id/accessViewPager"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </android.support.v4.view.ViewPager>

</LinearLayout>

访问忘记密码.java

public class AccessForgotPassword extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        if (container == null) {
            return null;
        }
        return inflater.inflate(R.layout.access_forgot_password, container, false);
    }

}

access_forgot_password.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/accessForgotPasswordMainLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="#FF0000">
</LinearLayout>

访问登录.java

public class AccessLogin extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        if (container == null) {
            return null;
        }
        return inflater.inflate(R.layout.access_login, container, false);
    }

}

access_login.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/accessLoginMainLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="#00FF00">
</LinearLayout>

访问注册.java

public class AccessRegister extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        if (container == null) {
            return null;
        }
        return inflater.infalte(R.layout.access_register, container, false);
    }

}

access_register.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/accessRegisterMainLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="#0000FF">
</LinearLayout>

Answer 1

设置

accessViewPager.setCurrentItem(1);