嘗試setOnItemSelectedListener（this）時應用程序崩潰;

Question

嗨，大家好我正在開發一個應用程序。我想用它從紡紗人中選擇他/她的生日。我將根據spinner3更改天數。如果用戶選擇一個有30天的月份，我的應用程序需要設置微調器4只包含高達30的數字。當用戶選擇一個微調器項目3時，我需要此設置。 但我的應用程序崩潰時，我打開它。它不會崩潰，如果我註釋掉這一行： spinner3.setOnItemSelectedListener（this）;（解決了這個）

新的問題：它運行onItemSelected（適配器視圖父，觀景，詮釋POS，長ID）唯一的

希望你能找到的問題。由於

SignUp2.java：

package com.geniboys.sosyaaal; 

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

import android.app.ActionBar; 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.View; 
import android.widget.AdapterView; 
import android.widget.ArrayAdapter; 
import android.widget.Spinner; 

public class SignUp2 extends Activity implements 
AdapterView.OnItemSelectedListener { 

    Spinner spinner4 = (Spinner) findViewById(R.id.spinner4); 
    Spinner spinner2 = (Spinner) findViewById(R.id.spinner2); 
    Spinner spinner3 = (Spinner) findViewById(R.id.spinner3); 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_sign_up2); 

     ActionBar actionBar = getActionBar(); 
     actionBar.hide(); 


     List<String> list = new ArrayList<String>(); 

     Calendar c = Calendar.getInstance(); 
     int year = c.get(Calendar.YEAR); 

     for(int i = 1972; i <= year+4; ++i) 
     { 
      String foo = Integer.toString(i); 
      list.add(foo); 
     } 

     ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, list); 
     dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
     spinner2.setAdapter(dataAdapter); 

     spinner3.setOnItemSelectedListener(this); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.sign_up2, menu); 
     return true; 
    } 


     public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) 
     { 
      // An item was selected. You can retrieve the selected item using 
      String ay = (String) parent.getItemAtPosition(pos); 

      List<String> list = new ArrayList<String>(); 

      if(ay == "Ocak" || ay == "Mart" || ay == "Mayıs" || ay == "Temmuz" || ay == "Ekim" || ay == "Aralık") 
      { 
       for(int i = 1; i<=31; ++i) 
       { 
        String foo = Integer.toString(i); 
        list.add(foo); 
       } 
      } 
      if(ay == "Şubat") 
      { 
       for(int i = 1; i<=28; ++i) 
       { 
        String foo = Integer.toString(i); 
        list.add(foo); 
       } 
      } 
      else 
      { 
       for(int i = 1; i<=30; ++i) 
       { 
        String foo = Integer.toString(i); 
        list.add(foo); 
       } 
      } 



     ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(SignUp2.this, android.R.layout.simple_spinner_item, list); 
     dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
     spinner4.setAdapter(dataAdapter);   
    } 

    @Override 
    public void onNothingSelected(AdapterView<?> arg0) 
    { 

    } 



    public void geri(View view) 
    { 
     super.onBackPressed(); 
    } 

    public void ileri(View view) 
    { 

    } 

} 

activity_sign_up2.xml：

<RelativeLayout xmlns:tools="http://schemas.android.com/tools" 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:background="@drawable/registerbackground" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    tools:context=".SignUpActivity" > 

    <Button 
     android:id="@+id/button2" 
     style="?android:attr/buttonStyleSmall" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignBottom="@+id/textView4" 
     android:layout_alignRight="@+id/editText1" 
     android:onClick="ileri" 
     android:text="@string/layoutIleri" 
     android:textColor="#ffffff" /> 

    <TextView 
     android:id="@+id/textView1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentTop="true" 
     android:layout_marginLeft="28dp" 
     android:layout_marginTop="70dp" 
     android:text="@string/loginTanim" 
     android:textColor="#ffffff" 
     android:textSize="20sp" /> 

    <TextView 
     android:id="@+id/textView4" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentTop="true" 
     android:layout_centerHorizontal="true" 
     android:layout_marginTop="30dp" 
     android:text="@string/loginKayit" 
     android:textAppearance="?android:attr/textAppearanceLarge" 
     android:textColor="#ffffff" /> 

    <Button 
     android:id="@+id/button1" 
     style="?android:attr/buttonStyleSmall" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignBottom="@+id/textView4" 
     android:layout_alignLeft="@+id/textView1" 
     android:onClick="geri" 
     android:text="@string/layoutGeri" 
     android:textColor="#ffffff" /> 

    <EditText 
     android:id="@+id/editText1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_below="@+id/textView1" 
     android:layout_toRightOf="@+id/textView1" 
     android:ems="10" 
     android:hint="@string/loginAdhint" 
     android:textColor="#ffffff" /> 

    <Spinner 
     android:id="@+id/spinner2" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignRight="@+id/editText1" 
     android:layout_alignTop="@+id/textView3" 
     android:layout_toRightOf="@+id/textView3" 
     android:textColor="#ffffff" /> 

    <EditText 
     android:id="@+id/editText2" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_above="@+id/textView2" 
     android:layout_alignLeft="@+id/textView1" 
     android:layout_alignRight="@+id/textView2" 
     android:textColor="#ffffff" 
     android:ems="10" > 

    </EditText> 

    <EditText 
     android:id="@+id/editText3" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignRight="@+id/textView1" 
     android:layout_below="@+id/textView1" 
     android:layout_toRightOf="@+id/editText2" 
     android:textColor="#ffffff" 
     android:ems="10" /> 
    <requestFocus /> 

    <Spinner 
     android:id="@+id/spinner1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignLeft="@+id/spinner2" 
     android:layout_alignTop="@+id/textView2" 
     android:entries="@array/loginSehirler" 
     android:prompt="@string/loginMemlekethint" 
     android:textColor="#ffffff" /> 

    <TextView 
     android:id="@+id/textView2" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignLeft="@+id/TextView01" 
     android:layout_below="@+id/editText3" 
     android:layout_marginTop="24dp" 
     android:text="@string/loginMemleket" 
     android:textColor="#ffffff" 
     android:textSize="20sp" /> 

    <TextView 
     android:id="@+id/TextView01" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_below="@+id/spinner2" 
     android:layout_toLeftOf="@+id/spinner2" 
     android:text="@string/loginDogumTarihi" 
     android:textColor="#ffffff" 
     android:textSize="20sp" /> 

    <TextView 
     android:id="@+id/textView3" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignRight="@+id/textView4" 
     android:layout_below="@+id/spinner1" 
     android:text="@string/loginMezuniyet" 
     android:textColor="#ffffff" 
     android:textSize="20sp" /> 

    <Spinner 
     android:id="@+id/spinner3" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_below="@+id/TextView01" 
     android:layout_marginTop="11dp" 
     android:layout_toLeftOf="@+id/editText3" 
     android:entries="@array/loginAylar" 
     android:prompt="@string/loginAylarhint" /> 

    <Spinner 
     android:id="@+id/spinner5" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignBottom="@+id/spinner4" 
     android:layout_alignLeft="@+id/spinner2" 
     android:layout_alignParentRight="true" /> 

    <Spinner 
     android:id="@+id/spinner4" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignBottom="@+id/spinner3" 
     android:layout_alignTop="@+id/spinner3" 
     android:layout_toLeftOf="@+id/spinner5" 
     android:layout_toRightOf="@+id/spinner3" /> 

</RelativeLayout> 

編輯：添加的logcat：

01-23 18:31:49.730: W/InputEventReceiver(28607): Attempted to finish an input event but the input event receiver has already been disposed. 
01-23 18:31:49.730: W/InputEventReceiver(28607): Attempted to finish an input event but the input event receiver has already been disposed. 
01-23 18:31:53.150: W/InputEventReceiver(28607): Attempted to finish an input event but the input event receiver has already been disposed. 
01-23 18:31:57.930: W/InputEventReceiver(28607): Attempted to finish an input event but the input event receiver has already been disposed. 
01-23 18:32:00.270: W/InputEventReceiver(28607): Attempted to finish an input event but the input event receiver has already been disposed. 
01-23 18:32:10.310: W/InputEventReceiver(28607): Attempted to finish an input event but the input event receiver has already been disposed. 

編輯：添加ANSWER

我不能回答我的問題。請添加這個屁股的答案：

在此更改if語句：

if(ay == "Ocak" || ay == "Mart" || ay == "Mayıs" || ay == "Temmuz" || ay == "Ekim" || ay == "Aralık") 
    { 
     for(int i = 1; i<=31; ++i) 
     { 
      String foo = Integer.toString(i); 
      list.add(foo); 
     } 
    } 
    if(ay == "Şubat") 
    { 
     for(int i = 1; i<=28; ++i) 
     { 
      String foo = Integer.toString(i); 
      list.add(foo); 
     } 
    } 
    else 
    { 
     for(int i = 1; i<=30; ++i) 
     { 
      String foo = Integer.toString(i); 
      list.add(foo); 
     } 
    } 

到

 if(ay.equals("Ocak") || ay.equals("Mart") || ay.equals("Mayıs") || ay.equals("Temmuz") || ay.equals("Ekim") || ay.equals("Aralık")) 
     { 
      for(int i = 1; i<=31; ++i) 
      { 
       String foo = Integer.toString(i); 
       list.add(foo); 
      } 
     } 
     else if(ay.equals("Şubat")) 
     { 
      for(int i = 1; i<=28; ++i) 
      { 
       String foo = Integer.toString(i); 
       list.add(foo); 
      } 
     } 
     else 
     { 
      for(int i = 1; i<=30; ++i) 
      { 
       String foo = Integer.toString(i); 
       list.add(foo); 
      } 
     } 

那裏面並宣佈方法紡紗解決了這個問題。感謝所有幫助過的人。

Answer 1

您不能在方法外部初始化Views。這將嘗試在layout被設置之前初始化它們，這意味着它們將是null，因爲它們存在於您的layout中。將其更改爲

public class SignUp2 extends Activity implements 
AdapterView.OnItemSelectedListener { 

//declare here 
Spinner spinner4; 
Spinner spinner2; 
Spinner spinner3; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_sign_up2); 

    //initialize here after you have called setContentView() 
    spinner4 = (Spinner) findViewById(R.id.spinner4); 
    spinner2 = (Spinner) findViewById(R.id.spinner2); 
    spinner3 = (Spinner) findViewById(R.id.spinner3); 

題外話在某些時候，你會想學會給您View S和其他變量更具體的，有意義的名稱。你有3 Spinners和知道哪些實際上會做什麼將有所幫助，如果他們的意思是像truckSpinner，例如，因爲當我看到這個名字，我知道這是Spinner我指定爲一個選擇卡車。

Answer 2

初始化您的微調器的setContentView（）中的onCreate（其他人）後，你將獲得NullPointerException-

spinner4 = (Spinner) findViewById(R.id.spinner4); 
spinner2 = (Spinner) findViewById(R.id.spinner2); 
spinner3 = (Spinner) findViewById(R.id.spinner3);