如何解决The method getId() is undefined for the type String问题 java web问题
（1）package com.share.ORM;

import com.share.ORM.NewsColumns;

/**
 * NewsColumns entity. @author MyEclipse Persistence Tools
 */

public class NewsColumns implements java.io.Serializable {

// Fields

private Integer id;
private Integer parentId;
private String columnCode;
private String columnName;
private NewsColumns newsColumns;
private String NewsColumns;

// Constructors

/** default constructor */
public NewsColumns() {
}

/** full constructor */
public NewsColumns(Integer parentId, String columnCode, String columnName) {
this.parentId = parentId;
this.columnCode = columnCode;
this.columnName = columnName;
}

// Property accessors

public Integer getId() {
return this.id;
}

public void setId(Integer id) {
this.id = id;
}

public Integer getParentId() {
return this.parentId;
}

public void setParentId(Integer parentId) {
this.parentId = parentId;
}

public String getColumnCode() {
return this.columnCode;
}

public void setColumnCode(String columnCode) {
this.columnCode = columnCode;
}

public String getColumnName() {
return this.columnName;
}

public void setColumnName(String columnName) {
this.columnName = columnName;
}
public void setNewscolumns(NewsColumns newscolumns) {
this.setNewsColumns(newscolumns);
}

public String getNewsColumns() {
// TODO Auto-generated method stub
return this.NewsColumns;
}

public void setNewsColumns(NewsColumns newsColumns) {
this.newsColumns = newsColumns;
}

}


（2）package com.share.action;

import java.io.UnsupportedEncodingException;
import java.util.List;
import com.share.ORM.NewsColumns;
import com.share.service.ColumnsService;
import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ModelDriven;

/** 新闻栏目管理控制器 */
@SuppressWarnings("serial")
public class ColumnsAction extends ActionSupport implements ModelDriven<NewsColumns>{
/** 通过依赖注入ColumnsService组件实例 */
ColumnsService service;

/** 新闻栏目管理所有请求中常用的参数值 */
private String actionMsg; //Action间传递的消息参数
private List<NewsColumns> columnsList; //新闻栏目列表
private String parentid; //上级栏目的ID

//采用模型驱动
private NewsColumns model=new NewsColumns();//用于封装新闻栏目属性的模型实例
public NewsColumns getModel() {
return model;
}

/** 处理浏览新闻栏目请求 */
public String browseColumns(){
if(actionMsg!=null){
try {
actionMsg = new String(actionMsg.getBytes("ISO8859-1"),"gbk");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
addActionMessage(actionMsg);
}
columnsList = service.browseColumns();//调用业务逻辑组件取得新闻栏目列表
return SUCCESS;
}

/** 处理新增新闻栏目请求 */
public String addColumns(){
NewsColumns tempColumns = new NewsColumns();
tempColumns.setColumnName(model.getColumnName());
tempColumns.setColumnCode(model.getColumnCode());
if(parentid!=null && Integer.parseInt(parentid)>0){
tempColumns.setNewscolumns(service.loadColumns(Integer.valueOf(parentid)));
}
if (service.saveOrUpdateColumns(tempColumns)){//调用业务逻辑组件保存新增的新闻栏目
addActionMessage(getText("columns_