Question

我制作了两个旋转器，我的第二个旋转器依赖于第一个旋转器。当我点击第二个微调器时，我的程序崩溃了。这就是我的logcat所说的：

03-11 12:09:35.076: ERROR/AndroidRuntime(367): FATAL EXCEPTION: main
03-11 12:09:35.076: ERROR/AndroidRuntime(367): java.lang.NullPointerException
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:355)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.widget.ArrayAdapter.getDropDownView(ArrayAdapter.java:376)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.widget.Spinner$DropDownAdapter.getDropDownView(Spinner.java:332)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.widget.Spinner$DropDownAdapter.getView(Spinner.java:328)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.widget.AbsListView.obtainView(AbsListView.java:1409)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.widget.ListView.measureHeightOfChildren(ListView.java:1216)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.widget.ListView.onMeasure(ListView.java:1127)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.view.View.measure(View.java:8313)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1017)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:386)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:309)
03-11 12:09:35.076: ERROR/AndroidRuntime(367):     at android.view.View.measure(View.java:8313)

这是我的代码：

package com.test;


import java.io.IOException;

import org.json.JSONException;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Spinner;
import android.widget.Toast;

public class SearchActivity extends Activity implements AdapterView.OnItemSelectedListener
{

     boolean flag=true;
     Spinner spinner;
     public String [] doctorsname=new String[1000];

    String[] items = {"psychologist", "neurologist","dentist"};

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);


        setContentView(R.layout.searchact);

        for(int i=0;i<1000;i++)
         doctorsname[i]=null;

        Button b=(Button)findViewById(R.id.button2);
        Button b1=(Button)findViewById(R.id.button3);

        spinner = (Spinner) findViewById(R.id.spinner1);
        ArrayAdapter<CharSequence> adapter = new ArrayAdapter(this, android.R.layout.simple_spinner_item,items);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);

        spinner.setOnItemSelectedListener(this);

        b.setOnClickListener(new View.OnClickListener() {


        public void onClick(View v) 
        {
            Intent i = new Intent(SearchActivity.this,DocprofileextActivity.class);
            startActivity(i);       
        }
    });

        b1.setOnClickListener(new View.OnClickListener() {


        public void onClick(View v) 
        {
            Intent i = new Intent(SearchActivity.this,DocprofileextActivity.class);
            startActivity(i);       
        }
    });
    }

    public void onItemSelected(AdapterView<?> parent, View view, int position,long id) 
    {

         if(parent==spinner)
         {
            Toast toast = Toast.makeText(this, items[position], 2000);
            toast.show();

            logintosever obj1=new logintosever();

            try 
            {
                doctorsname=obj1.searchbycategory(items[position]);
            }
            catch (IOException e) 
            {
                e.printStackTrace();
            }
            catch (JSONException e) 
            {
                e.printStackTrace();
                flag=false;
            }

            Spinner spinner = (Spinner) findViewById(R.id.doctorsname);

            if(doctorsname!=null)
            {
                ArrayAdapter<CharSequence> adapter = new ArrayAdapter(this, android.R.layout.simple_spinner_item,doctorsname);
                adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
                spinner.setEnabled(true);
                spinner.setAdapter(adapter);
            }
            else
            {
                spinner.setEnabled(false);
            }
         }

    }

    public void onNothingSelected(AdapterView<?> arg0) 
    {

    }


    public void onItemSelected2(AdapterView<?> parent, View view, int position,long id) 
    {
    }


}

Answer 1

我首先向你发表评论，因为它们看起来更重要：

请回到原来的问题并接受答案 - how does accepting an answer works - 这也解释了为什么你应该这样做..
请您在下次发布代码时尝试删除不相关的代码，这会使您有机会阅读代码。

关于你的问题我不是很确定但是它的NullPointerException意味着你试图在一个不接受null的地方使用一个带空值的变量也许会尝试将你的吐司变量更改为 -

Toast toast = Toast.makeText(this, "item:"+items[position], 2000);

所以你不能把null放在吐司里面。

Answer 2

主要问题是您的数组大小与您的适配器不匹配，假设您的数组是10个元素，而您的适配器只有5个元素，

装置 string [10] = {“a”，“b”，“c”，“d”，“e”};

微调器onItemSelected制作问题

2 个答案: