Operator '==' cannot be applied to错误

Operator ‘==’ cannot be applied to ‘long,int’, ‘null’

一个类型为long,不是包装类型Long,所以不能为空，把long 改为Long,问题解决。

Operator ‘==’ cannot be applied to ‘char’, ‘java.lang.String’

一个类型为long，一个类型为String，把" "改为’ '，问题解决。

CSS 问题：Operator ‘===’ cannot be applied to types ‘number’ and 'string

<div [ngClass]="(cfgSelected ==='1')?'isActive':'isNormal'" 
     (click)="selectThisOne('1')">
bla ...
</div>

把 (cfgSelected ===‘1’) 改成 (cfgSelected === 1)，问题解决。