将数据从一个设计选项卡传递到另一选项卡

Each fragment is associated with the parent activity. so you can't directly communicate from one fragment to another fragment. You will need to go through Parent Activity using interface.

Check this docs : https://developer.android.com/training/basics/fragments/communicating.html

On button click pass the value to methods in your custom interface and access those methods in second fragment.

when I try to swipe to FragmentTwo nothing gets called in FragmentTwo

为此，您需要实现片段生命周期-https: //developer.android.com/reference/android/app/Fragment.html

更新

在您的代码中进行了一些修改后，只需查看以下内容即可。代码 -

Manifex.xml

<application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity"
            android:theme="@style/Theme.AppCompat.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

MainActivity.java

package com.app.onkar.tabdemo;

import android.support.v4.app.Fragment;
import android.support.design.widget.TabLayout;

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.os.Bundle;
import android.support.v7.widget.Toolbar;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements ViewPager.OnPageChangeListener {

    private Toolbar toolbar;
    private TabLayout tabLayout;
    private ViewPager viewPager;

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

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

        viewPager = (ViewPager) findViewById(R.id.viewpager);
        tabLayout = (TabLayout) findViewById(R.id.tabs);


        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());

        adapter.addFragment(new FragmentOne(), "ONE");
        adapter.addFragment(new FragmentTwo(), "TWO");
        viewPager.setAdapter(adapter);

        viewPager.addOnPageChangeListener(this);
        tabLayout.setupWithViewPager(viewPager);
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

    }

    @Override
    public void onPageSelected(int position) {
        System.out.println("onPageSelected Called");
    }

    @Override
    public void onPageScrollStateChanged(int state) {

    }

    public static class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();
        private static int count = 2;

        public void addFragment(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

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

        @Override
        public Fragment getItem(int position) {

            switch (position) {
                case 0:
                    return new FragmentOne();
                case 1:
                    return new FragmentTwo();
            }
            return null;
        }

        @Override
        public int getCount() {
            return count;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
                case 0:
                    return "Tab One";
                case 1:
                    return "Tab Two";
            }
            return null;
        }
    }
}

FragmentOne.java

package com.app.onkar.tabdemo;

import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;

public class FragmentOne extends Fragment {
    private EditText editText;
    private Button btnSendData;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        System.out.println("IN FRAGMENT ONE");
        View view = inflater.inflate(R.layout.fragment_one,container,false);

        editText = (EditText) view.findViewById(R.id.et_name);
        btnSendData = (Button) view.findViewById(R.id.btn_send);

        btnSendData.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                FragmentTwo fragment = new FragmentTwo();
                Bundle bundle = new Bundle();
                bundle.putString("username",editText.getText().toString());
                fragment.setArguments(bundle);
                getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.second_frag,fragment).commit();
            }
        });

        return view;
    }
}

FragmentTwo.java

package com.app.onkar.tabdemo;


import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;


public class FragmentTwo extends Fragment {

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        System.out.println("IN FRAGMENT TWO");
        View view = inflater.inflate(R.layout.fragment_two,container,false);
        TextView txt2 = (TextView) view.findViewById(R.id.textView2);
        Bundle bundle = getArguments();
        if(bundle!= null)
        {
            String value = getArguments().getString("username");
            txt2.setText(value);
        }
        return  view;
    }

    @Override
    public void onResume() {
        super.onResume();
        System.out.println("onResume gets called");
    }

}

布局文件没有变化。只需尝试上面的代码-它完全可以按照您想要的方式工作。希望对您有所帮助！

屏幕