遇到个需求就是计算过去的6个月是哪几个月 开始随便从网上找了个，  

  public static String[] getLastMonths(Calendar theCal) {
    String[] lastMonths = new String[6];
    Calendar cal = theCal;//Calendar.getInstance();
    cal.set(Calendar.MONTH, cal.MONTH); //要先+1,才能把本月的算进去
    
    for(int i=0; i<6; i++){
      cal.set(Calendar.MONTH, cal.get(Calendar.MONTH)-1); //逐次往前推1个月
      String t = cal.get(Calendar.YEAR)+ "-" + fillZero((cal.get(Calendar.MONTH)+1), 2);
      
      lastMonths[5-i] = t.replace("-", "");
    }
    
    return lastMonths;
  }

 

但是运行时候出现了连续的问题，输入为201908时，会输出 201907 201907 201906 201905 201904 201903

或者 201907 201906 201905 201904 201904 201903

后来又写了个：

正确的月份-1

 

  public static String[] getLastMonths(Calendar theCal) {
    String[] lastMonths = new String[6];
    Calendar cal = theCal;//Calendar.getInstance();
    cal.set(Calendar.MONTH, cal.get(Calendar.MONTH)); //要先+1,才能把本月的算进去
    
    for(int i=0; i<6; i++){
      cal.add(Calendar.MONTH, -1); //逐次往前推1个月
      String t = cal.get(Calendar.YEAR)+ "-" + fillZero((cal.get(Calendar.MONTH)+1), 2);
      
      lastMonths[5-i] = t.replace("-", "");
    }
    
    return lastMonths;
  }

 

 

怀疑是cal.set(Calendar.MONTH, cal.get(Calendar.MONTH)-1);的初始化有问题，老是慢一拍，感觉有的时候这个-1并不能正常执行，就开始向下执行了，

所以，还是用这个正常的吧， cal.add(Calendar.MONTH, -1); //逐次往前推1个月