不打印我的切换语句，我不知道为什么？ Java

Question

根据我输入的大小写，我的切换语句不打印。这是我的代码。在Java中遇到这个问题，这非常令人沮丧。

     if (gender == "M"){
        switch (activity){
         case 1:
        newMbmr = (candy1 * .2) + candy1;
        System.out.println("A male should eat no more than " +String.format("%.0f", newMbmr) + " candy bars per day to maintain his weight.");
        break;
        case 2:
        newMbmr = (candy1 * .3) + candy1;
        System.out.println("A male should eat no more than " +String.format("%.0f", newMbmr) + " candy bars per day to maintain his weight.");
        break;
        case 3:
        newMbmr = (candy1 * .4) + candy1;
        System.out.println("A male should eat no more than " +String.format("%.0f", newMbmr) + " candy bars per day to maintain his weight.");
        break;
        case 4:
        newMbmr = (candy1 * .5) + candy1;
        System.out.println("A male should eat no more than " +String.format("%.0f", newMbmr) + " candy bars per day to maintain his weight.");
    }
}
    else if (gender == "F" ){

        switch (activity){

        case 1:
        newWbmr = (candy2 * 1.2) ;
        System.out.println("A female should eat no more than " +String.format("%.0f", newWbmr) + " candy bars per day to maintain her weight.");
        break;
        case 2:
        newWbmr = (candy2 * 1.3) ;
        System.out.println("A female should eat no more than " +String.format("%.0f", newWbmr) + " candy bars per day to maintain her weight.");
        break;
        case 3:
        newWbmr = (candy2 * 1.4) ; 
        System.out.println("A female should eat no more than " +String.format("%.0f", newWbmr) + " candy bars per day to maintain her weight.");
        break;
        case 4:
        newWbmr = (candy2 * 1.5) ;
        System.out.println("A female should eat no more than " +String.format("%.0f", newWbmr) + " candy bars per day to maintain her weight.");

        break;
    }
}

它要我输入活动级别，然后我停止执行代码。这很令人困惑，因为它应该根据选择的大小写正确的打印语句。