Android 我的动态滑块上的NullException

我想问一下，每次到达int[]数组中的最后一个对象时，如何处理NullException

这是我的信息标签

package com.example.aldrinjohn.milktracktest;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;

/**
 * Created by Aldrin John on 3/20/2017.
 */

public class InformationTab extends Fragment{
    ViewPager viewPager;
    CustomSwipeAdapter adapter;
    Button btnTrivia,btnBenefitB,btnBenefitM,btnPump,btnStoring,btnInfo;
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.informationtab, container, false);
        viewPager = (ViewPager)rootView.findViewById(R.id.view_pager);

        btnTrivia = (Button)rootView.findViewById(R.id.trivia);
        btnTrivia.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                GlobalVariables.buttonClick = "trivia";
                adapter = new CustomSwipeAdapter(getActivity());
                viewPager.setAdapter(adapter);
            }
        });
        btnBenefitB = (Button)rootView.findViewById(R.id.benefit_babies);
        btnBenefitB.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                GlobalVariables.buttonClick = "benefitb";
                adapter = new CustomSwipeAdapter(getActivity());
                viewPager.setAdapter(adapter);
            }
        });
        btnBenefitM = (Button)rootView.findViewById(R.id.benefit_mother);
        btnBenefitM.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                GlobalVariables.buttonClick = "benefitm";
                adapter = new CustomSwipeAdapter(getActivity());
                viewPager.setAdapter(adapter);
            }
        });
        btnPump = (Button)rootView.findViewById(R.id.pump);
        btnPump.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                GlobalVariables.buttonClick = "pump";
                adapter = new CustomSwipeAdapter(getActivity());
                viewPager.setAdapter(adapter);
            }
        });
        btnStoring = (Button)rootView.findViewById(R.id.storing);
        btnStoring.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                GlobalVariables.buttonClick = "storing";
                adapter = new CustomSwipeAdapter(getActivity());
                viewPager.setAdapter(adapter);
            }
        });
        btnInfo = (Button)rootView.findViewById(R.id.tips);
        btnInfo.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                GlobalVariables.buttonClick = "tips";
                adapter = new CustomSwipeAdapter(getActivity());
                viewPager.setAdapter(adapter);
            }
        });

        return rootView;

    }

}

这是我的

package com.example.aldrinjohn.milktracktest;

import android.content.Context;
import android.provider.ContactsContract;
import android.support.v4.view.PagerAdapter;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;

import com.google.android.gms.ads.formats.NativeAd;
import com.google.android.gms.tagmanager.Container;

/**
 * Created by Aldrin John on 3/26/2017.
 */

public class CustomSwipeAdapter extends PagerAdapter{
    private int[] trivia = {R.drawable.c1,R.drawable.c2,R.drawable.c3,R.drawable.c4, R.drawable.c5,R.drawable.c6};
    private int[] benefitBaby = {R.drawable.c7,R.drawable.c8,R.drawable.c9};
    private int[] benefitMother = {R.drawable.c91,R.drawable.c92};
    private int[] info = {R.drawable.a1,R.drawable.a2,R.drawable.a3,R.drawable.a4,R.drawable.a5,R.drawable.a6,R.drawable.a7,
                            R.drawable.a8,R.drawable.a9,R.drawable.a91,R.drawable.a92};
    private int[] storing = {R.drawable.b1,R.drawable.b2,R.drawable.b3,R.drawable.b4};
    private int[] pump = {R.drawable.a21,R.drawable.a22,R.drawable.a23,R.drawable.a24,R.drawable.a25,R.drawable.a31,R.drawable.a32,
            R.drawable.a33,R.drawable.a34,R.drawable.a35,R.drawable.pic1,R.drawable.pic2,R.drawable.pic3,R.drawable.pic4,R.drawable.pic5};

    private Context ctx;
    private LayoutInflater layoutInflater;

    public CustomSwipeAdapter(Context ctx)
    {
        this.ctx = ctx;
    }

    @Override
    public int getCount() {
        return pump.length;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return (view==(LinearLayout)object);
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position){

        layoutInflater = (LayoutInflater)ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        final View item_view = layoutInflater.inflate(R.layout.swipe_layout,container,false);
        ImageView imgTrivia = (ImageView)item_view.findViewById(R.id.image_view);

        if(GlobalVariables.buttonClick.equals("trivia"))
        {
            imgTrivia.setImageResource(trivia[position]);
        }
        else if (GlobalVariables.buttonClick.equals("benefitb"))
        {
            imgTrivia.setImageResource(benefitBaby[position]);
        }
        else if (GlobalVariables.buttonClick.equals("benefitm"))
        {
            imgTrivia.setImageResource(benefitMother[position]);
        }
        else if (GlobalVariables.buttonClick.equals("storing"))
        {
            imgTrivia.setImageResource(storing[position]);
        }
        else if (GlobalVariables.buttonClick.equals("tips"))
        {
            imgTrivia.setImageResource(info[position]);
        }
        else if (GlobalVariables.buttonClick.equals("pump"))
        {
            imgTrivia.setImageResource(pump[position]);
        }

        container.addView(item_view);

        return item_view;
    }
@Override
    public void destroyItem(ViewGroup container, int position, Object object){
        container.removeView((LinearLayout)object);
    }


}

---

解决了！我刚刚使用了一个全局变量类，它包含单击的幻灯片数量。并将其返回给getCount函数

全局变量类？听起来是个糟糕的主意。您只需要在getCount中返回一些值。您可以改为创建“成员变量”