Fragment+Viewpaager

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

    <android.support.v4.view.ViewPager
        android:id="@+id/Mypager"
        android:layout_width="match_parent"
        android:layout_height="150dp"></android.support.v4.view.ViewPager>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <EditText
            android:id="@+id/editquery"
            android:layout_weight=""
            android:hint="请输入要查询的城市"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
        <Button
           android:id="@+id/weatherquery"
            android:layout_weight=""
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="查询天气"/>
    </LinearLayout>
    <TextView
        android:id="@+id/weatherText"
        android:layout_width="match_parent"
        android:layout_height="150dp" />

</LinearLayout>

package com.example.shexinhai_08222;

import android.graphics.Color;
import android.os.Handler;
import android.os.Message;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private ViewPager viewPager1;
    private Button btnweather,btnlvshi;
    ArrayList<Button> viewlist = new ArrayList<Button>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.item);

        initView();
        viewPager1.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {

            @Override
            public int getCount() {
                return ;
            }
            @Override
            public Fragment getItem(int position) {
              Fragment fragment = null;

               switch (position){
                   case :
                       fragment = new WeatherFragment();
                       break;
                   case :
                       fragment = new LvshiFragment();
                       break;
               }
                return fragment;
            }
        });

        viewPager1.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }
            @Override
            public void onPageSelected(int position) {
                for(int i = ;i<viewlist.size();i ++){
                    Button button = viewlist.get(i);
                    if (i==position) {
                        button.setTextColor(Color.RED);
                    }else {
                        button.setTextColor(Color.BLACK);
                    }
                }
            }
            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

    }
    private void initView(){

        viewPager1 = (ViewPager) findViewById(R.id.mypagerall);
        btnweather = (Button) findViewById(R.id.weather);
        btnlvshi = (Button) findViewById(R.id.lvshi);

        viewlist.add(btnweather);
        viewlist.add(btnlvshi);

        for (int i = ;i<viewlist.size();i++){
            viewlist.get(i).setOnClickListener(this);
        }
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.weather:
                viewPager1.setCurrentItem();
                break;
            case R.id.lvshi:
                viewPager1.setCurrentItem();
                break;
        }
    }

}