Viewpager编辑？

Question

我对Android很新，我试图自定义android studio的默认视图寻呼机。 。我试图获取查看寻呼机的页码，例如为每个页面设置不同的图像。

    package blabla.example.com.bla;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;


public class MainActivity extends AppCompatActivity {

    /**
     * The {@link android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. We use a
     * {@link FragmentPagerAdapter} derivative, which will keep every
     * loaded fragment in memory. If this becomes too memory intensive, it
     * may be best to switch to a
     * {@link android.support.v4.app.FragmentStatePagerAdapter}.
     */
    private SectionsPagerAdapter mSectionsPagerAdapter;

    /**
     * The {@link ViewPager} that will host the section contents.
     */
    private ViewPager mViewPager;

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


        // Create the adapter that will return a fragment for each of the three
        // primary sections of the activity.
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);

    }



    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        private static final String ARG_SECTION_NUMBER = "section_number";

        public PlaceholderFragment() {
        }

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;



    }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
             View rootView = inflater.inflate(R.layout.fragment_main, container, false);
             TextView textView = (TextView) rootView.findViewById(R.id.section_label);
            textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));


            ImageView levelImage = (ImageView) rootView.findViewById(R.id.imageView3);

            if (!ARG_SECTION_NUMBER.equals("1")) {
                levelImage.setImageResource(R.drawable.example1);
            }
            else if (!ARG_SECTION_NUMBER.equals("2")) {
                levelImage.setImageResource(R.drawable.example2);
            }
            else if (!ARG_SECTION_NUMBER.equals("3")) {
                levelImage.setImageResource(R.drawable.example3);
            }
            else if (!ARG_SECTION_NUMBER.equals("4")) {
                levelImage.setImageResource(R.drawable.example4);
            }
            else {
                levelImage.setImageResource(R.drawable.example5);
            }




            return rootView;

        }
    }

    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            // getItem is called to instantiate the fragment for the given page.
            // Return a PlaceholderFragment (defined as a static inner class below).
            return PlaceholderFragment.newInstance(position + 1);
        }

        @Override
        public int getCount() {
            // Show 5 total pages.
            return 5;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
                case 0:
                    return "SECTION 1";
                case 1:
                    return "SECTION 2";
                case 2:
                    return "SECTION 3";
                case 3:
                    return "SECTION 4";
                case 4:
                    return "SECTION 5";
            }
            return null;
        }


    }
}

你可以看到我到目前为止尝试了这个：））

ImageView levelImage = (ImageView) rootView.findViewById(R.id.imageView3);

        if (!ARG_SECTION_NUMBER.equals("1")) {
            levelImage.setImageResource(R.drawable.example51);
        }
        else if (!ARG_SECTION_NUMBER.equals("2")) {
            levelImage.setImageResource(R.drawable.example2);
        }
        else if (!ARG_SECTION_NUMBER.equals("3")) {
            levelImage.setImageResource(R.drawable.example3);
        }
        else if (!ARG_SECTION_NUMBER.equals("4")) {
            levelImage.setImageResource(R.drawable.example4);
        }
        else {
            levelImage.setImageResource(R.drawable.example5);
        }

但它没有用。我该怎么办？

Answer 1

变量ARG_SECTION_NUMBER包含String，您只是将其用作在getArguments()捆绑中查找值的键。所以你应该改变你的代码：

if (getArguments().getInt(ARG_SECTION_NUMBER) == 1) {
    ...
}
else if (getArguments().getInt(ARG_SECTION_NUMBER) == 2) {
    ...
}

当然，一个更好的解决方案是将图像资源id直接放入包中，而不是仅仅放入一个节号，然后创建一个巨大的if / else树。像这样：

public static PlaceholderFragment newInstance(int sectionNumber, int drawableId) {
    PlaceholderFragment fragment = new PlaceholderFragment();
    Bundle args = new Bundle();
    args.putInt(ARG_SECTION_NUMBER, sectionNumber);
    args.putInt(ARG_DRAWABLE_ID, drawableId);
    fragment.setArguments(args);
    return fragment;
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    ...
    ImageView levelImage = (ImageView) rootView.findViewById(R.id.imageView3);
    levelImage.setImageResource(getArguments().getInt(ARG_DRAWABLE_ID));

    return rootView;
}