如何显示其他布局？

Question

我是android开发的新手，只是想一路学习！

我正在创建一个Android应用程序，该应用程序希望显示不同的视图，其中一个用于显示重量，天气和水合情况（现在我称它们为“视图”）。 尽管当我运行我的应用程序时，我只会显示一个视图。

为了在选项卡式视图中显示其他两个布局，我必须添加/修改什么代码？

这是我在MainActivity.java中的代码

    package com.oxinc.android.drate;

import android.support.design.widget.TabLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;

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.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;

import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    int quantity = 0;
    String outcome = "";
    int required = 0;
    int height = 0;

    /**
     * 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);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        // 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);

        //Tabbed Layout
        TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(mViewPager);

        //Floating Action Button
        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Are you hydrated?", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    /**
     * 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 static PlaceholderFragment fragment_main() {
            PlaceholderFragment fragment = new PlaceholderFragment();
            return fragment;
        }

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static PlaceholderFragment weight(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 hydration = inflater.inflate(R.layout.hydration, container, false);
            return hydration;
        }
    }

    /**
     * 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.weight(position + 1);
        }

        @Override
        public int getCount() {
            // Show 3 total pages.
            return 3;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
                case 0:
                    return "Hydration";
                case 1:
                    return "Weigh In";
                case 2:
                    return "Weather";
            }
            return null;
        }
    }

        public void eight(View view) {
            quantity = quantity + 8;
            displayQuantity(quantity);
        }

        public void twelve(View view) {
            quantity = quantity + 12;
            displayQuantity(quantity);
        }

        public void sixteen(View view) {
            quantity = quantity + 16;
            displayQuantity(quantity);
        }

        public void thirty_two(View view) {
            quantity = quantity + 32;
            displayQuantity(quantity);
        }

        public void sixty_four(View view) {
            quantity = quantity + 64;
            displayQuantity(quantity);
        }

        //Reset Button
        public void reset(View view) {
            quantity = 0;
            displayQuantity(quantity);
            outcome = "";
            displayOutcome(outcome);
        }

        //Starts the basic formula for oz. per day
        public int height(int value) {
            EditText height = (EditText) findViewById(R.id.height);
            String height_value = height.getText().toString();
            int int_height = Integer.parseInt(height_value);

            if (int_height >= 60) {
                required = 64;
            }
            return required;
        }
        /**
         * This method is called when the check button is clicked.
         */
        public String check(View view) {

            height((int) height);
            if (quantity >= required) {
                outcome = "You have met your goal!!";
            } else {
                outcome = "Keep trying you are almost there";
            }
            displayOutcome(outcome);
            return outcome;
        }

        //Displays the Outcome to the outcome text view
        public void displayOutcome(String n) {
            TextView outcomeTextView = (TextView) findViewById(
                    R.id.outcome_text_view);
            outcomeTextView.setText(outcome);
        }

        /**
         * This method displays the given quantity value on the screen.
         */
        public void displayQuantity(int quantity) {
            TextView quantityTextView = (TextView) findViewById(
                    R.id.quantity_text_view);
            quantityTextView.setText(quantity + "");
        }

}

一次运行它，我只会看到三个屏幕，如下所示：

Answer 1

在你里面
public Fragment getItem(int position) {
在你里面
public class SectionsPagerAdapter extends FragmentPagerAdapter {
实施此：

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                return new fragment1();
            case 1:
                return new fragment2();
            case 2:
                return new fragment3();
            default:
                // this should never happen
                return null;
                //return new Fragment();
        }
    }

其中“ fragment1-2和3”是您定义在此处运行的Java类的名称。

我完全按照这种方式使用“ getItem”，里面没有其他内容。 因此，我不知道您是否必须维护return PlaceholderFragment.weight(position + 1); 那里。 尝试将其注释掉，看看会发生什么。 我也不使用createview。 最好。

Answer 2

问题在这里

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

您总是在每个片段中都增加水合布局