Error when creating a pagination with apex - salesforce

Question

No errors on the apex class screen. An unexpected error occurs when you press the search button.
I got an error when I added the pagination code in the second half.
There was no problem before that.
Why?
public with sharing class AccountListCon {
static List<String> TARGET_FIELDS = new List<String>{
'Name'
};
public SearchCondition condition{ get;set; }
public List<AccountList__c> results { get;set; }
public String sortingField { get;set; }
public void init(){
this.condition = new SearchCondition();
this.results = new List<AccountList__c>();
}
public PageReference clear(){
init();
return null;
}
public PageReference search() {
if( condition.validate() ){
return null;
}
String soqlQuery = condition.getSoqlQuery();
System.debug('[soql] ' + soqlQuery);
try{
this.results = database.query(soqlQuery);
System.debug(this.results);
}catch(DmlException e){
ApexPages.addMessages(e);
System.debug('[DmlException]' + e);
}catch(Exception e){
ApexPages.addMessages(e);
System.debug('[Exception]' + e);
}
return null;
}
public PageReference sort(){
if(this.sortingField == null ){
return null;
}
if(this.sortingField == this.condition.sortkey){
this.condition.setOrderReverse();
}
else {
this.condition.sortkey = this.sortingField;
}
search();
return null;
}
public Class SearchCondition {
private Time JST_AM0 = Time.newInstance(9, 0, 0, 0);
public AccountList__c obj {get;set;}
public SearchCondition() {
this.obj = new AccountList__c();
sortkey = 'LastModifiedDate';
order = 'DESC';
}
public String getSoqlQuery(){
List<String> param = new String[]{ getFieldList(), getWhere(), getOrder() };
return String.format('SELECT {0} FROM AccountList__c {1} {2} LIMIT 500', param);
}
private String getFieldList(){
return String.join(TARGET_FIELDS, ',');
}
private String getWhere(){
List<String> param = new String[]{ };
--Omission--
if(param.isEmpty()){
return '';
}
return 'WHERE ' + String.join(param, ' AND ');
}
private String getOrder(){
List<String> param = new String[]{ sortkey, order };
return String.format('ORDER BY {0} {1}', param);
}
private DateTime adjustJSTtoGMS(DateTime day){
JST_AM0 = Time.newInstance(15, 0, 0, 0);
return Datetime.newInstance(day.date(), JST_AM0);
}
--Omission--
private static final Integer PAGE_SIZE = 10;
public Integer currentPage {get; set;}
public Integer totalPage {get; set;}
private ApexPages.StandardSetController ssController;
public Boolean getEnablePrev(){
return ssController.getHasPrevious();
}
public Boolean getEnableNext(){
return ssController.getHasNext();
}
public void PagingCtrl(){
}
public PageReference searchinit() {
ssController = new ApexPages.StandardSetController([SELECT Id, Name FROM Account]);
currentPage = ssController.getPageNumber();
ssController.setPageSize(PAGE_SIZE);
totalPage = (Integer)Math.ceil((Decimal)ssController.getResultSize() / PAGE_SIZE);
return null;
}
public void next() {
ssController.next();
currentPage = ssController.getPageNumber();
}
public void prev() {
ssController.previous();
currentPage = ssController.getPageNumber();
}
public List<Account> getAccountList(){
return (List<Account>)ssController.getRecords();
}
}
Attempt to de-reference a null object
FATAL_ERROR Class.AccountListCon.getEnablePrev: line 292, column 1
public Boolean getEnablePrev(){
return ssController.getHasPrevious();
}

Answer 1

It looks like getEnablePrev() is being called prior to searchInit(), where ssController is initialized. Your Visualforce page may be attempting to render the pagination area prior to completing the initialization of the required data; we couldn't tell the reason why without seeing the relevant portions of your Visualforce page.