集合类的一些知识

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1. map的key为非string对象时，如何判断key值是否存在

需要重写equals 方法和 hascode 方法，举例如下

    // 获取内部类对象
   public BiCostForExcel getBiCostForExcel(String moldNo,String workOrderNo,String inTime,String sectionName,String workType){
       return new BiCostForExcel(moldNo, workOrderNo, inTime, sectionName, workType);
   }

   // 内部类，用于加工工单导出EXCEL 构造数据
    public   class BiCostForExcel{
       private String moldNo ;
       private String workOrderNo ;
       private String inTime ;
       private String sectionName ;
       private String workType ;

       public BiCostForExcel(){}

       public BiCostForExcel(String moldNo,String workOrderNo,String inTime,String sectionName,String workType){
           this.moldNo = moldNo;
           this.workOrderNo = workOrderNo;
           this.inTime = inTime;
           this.sectionName = sectionName;
           this.workType = workType;
       }

    @Override
      public boolean equals(Object obj) {
            BiCostForExcel other = (BiCostForExcel) obj;
   // 增加equals true
                  if(moldNo.equals(other.moldNo)&&workOrderNo.equals(other.workOrderNo)&&inTime.equals(other.inTime)&&sectionName.equals(other.sectionName)&&workType.eq              uals(other.workType)){
               return true;
           }

@Override
       public int hashCode() {
           /*final int prime = 31;
           int result = 1;
           result = prime * result + getOuterType().hashCode();
           result = prime * result + ((inTime == null) ? 0 : inTime.hashCode());
           result = prime * result + ((moldNo == null) ? 0 : moldNo.hashCode());
           result = prime * result + ((sectionName == null) ? 0 : sectionName.hashCode());
           result = prime * result + ((workOrderNo == null) ? 0 : workOrderNo.hashCode());
           result = prime * result + ((workType == null) ? 0 : workType.hashCode());
           return result;*/

           int ret = new String(moldNo).hashCode() ^ new String(workOrderNo).hashCode()^ new String(sectionName).hashCode()^ new String(inTime).hashCode()^ new String(workType).hashCode();
           // 也可以用下面这种方式计算hashCode
           // int ret = String.valueOf(id).hashCode() ^ String.valueOf(type).hashCode();
                //System.out.println(ret);
           return ret;

       }

public static void main(String[] args) {
       BiCostForExcel biCostForExcel1 = new BiCostVo().getBiCostForExcel("1", "2", "2016/12/22", "CNC", "W");
       BiCostForExcel biCostForExcel2 = new BiCostVo().getBiCostForExcel("1", "2", "2016/12/22", "CNC", "W");
       System.out.println(biCostForExcel1==biCostForExcel2);
       System.out.println(biCostForExcel1.equals(biCostForExcel2));

       Map<BiCostForExcel, Double[]> map = new LinkedHashMap<BiCostForExcel, Double[]>();
       map.put(biCostForExcel1, new Double[]{3.2d,4.3d});
       System.out.println(map.containsKey(biCostForExcel2));
   }

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