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Android Java：将else-if转换为switch

[英]Android Java: Convert else-if to switch

 原文  2020-04-09 00:05:28  3   2    java/ android/ performance/ android-studio/ if-statement

问题描述

I use else-if statement to check Boolean values and since using the else-if, it causes poor performance.我使用 else-if 语句来检查 Boolean 值，并且由于使用 else-if，它会导致性能不佳。

From that reason, I am considering to convert the else-if statement into switch statement, so that I'd like to hear your advice to converting it appropriately.出于这个原因，我正在考虑将 else-if 语句转换为 switch 语句，以便我想听听您对它进行适当转换的建议。

This is my else-if statement这是我的 else-if 语句

public class Config_Monday_0 {
private Context mContext;

public Config_Monday_0(Context context){
    this.mContext = context;
}

public int monday_0(TextView mon_1, TextView mon_2, TextView mon_3, TextView mon_4, TextView mon_5,
                     TextView mon_6, TextView mon_7, TextView mon_8, TextView mon_9, TextView mon_10,
                     TextView mon_11, TextView mon_12, TextView mon_13, TextView mon_14, TextView mon_15,
                     TextView mon_16, TextView mon_17, TextView mon_18, TextView mon_19, TextView mon_20,
                     TextView mon_21, TextView mon_22, TextView mon_23, TextView mon_24){

    Schedule_Boolean_Monday_0 schedule_boolean_monday0 = new Schedule_Boolean_Monday_0(mContext);
    DatabaseTimetable databaseTimetable = new DatabaseTimetable(mContext);

    int start_time;
    int end_time;

    //Database 0 AM is not used
    if (!schedule_boolean_monday0.Monday_0_1() && !schedule_boolean_monday0.Monday_0_2() && !schedule_boolean_monday0.Monday_0_3() && !schedule_boolean_monday0.Monday_0_4() && !schedule_boolean_monday0.Monday_0_5() &&
            !schedule_boolean_monday0.Monday_0_6() && !schedule_boolean_monday0.Monday_0_7()&& !schedule_boolean_monday0.Monday_0_8() && !schedule_boolean_monday0.Monday_0_9() && !schedule_boolean_monday0.Monday_0_10() &&
            !schedule_boolean_monday0.Monday_0_11() && !schedule_boolean_monday0.Monday_0_12() && !schedule_boolean_monday0.Monday_0_13() && !schedule_boolean_monday0.Monday_0_14() && !schedule_boolean_monday0.Monday_0_15() &&
            !schedule_boolean_monday0.Monday_0_16() && !schedule_boolean_monday0.Monday_0_17()&& !schedule_boolean_monday0.Monday_0_18() && !schedule_boolean_monday0.Monday_0_19() && !schedule_boolean_monday0.Monday_0_20() &&
            !schedule_boolean_monday0.Monday_0_21() && !schedule_boolean_monday0.Monday_0_22() && !schedule_boolean_monday0.Monday_0_23() && !schedule_boolean_monday0.Monday_0_24()){
        return 0;
    }
    //0 am - 1 hr.
    else if (schedule_boolean_monday0.Monday_0_1() && !schedule_boolean_monday0.Monday_0_2() && !schedule_boolean_monday0.Monday_0_3() && !schedule_boolean_monday0.Monday_0_4() && !schedule_boolean_monday0.Monday_0_5() &&
            !schedule_boolean_monday0.Monday_0_6() && !schedule_boolean_monday0.Monday_0_7()&& !schedule_boolean_monday0.Monday_0_8() && !schedule_boolean_monday0.Monday_0_9() && !schedule_boolean_monday0.Monday_0_10() &&
            !schedule_boolean_monday0.Monday_0_11() && !schedule_boolean_monday0.Monday_0_12() && !schedule_boolean_monday0.Monday_0_13() && !schedule_boolean_monday0.Monday_0_14() && !schedule_boolean_monday0.Monday_0_15() &&
            !schedule_boolean_monday0.Monday_0_16() && !schedule_boolean_monday0.Monday_0_17()&& !schedule_boolean_monday0.Monday_0_18() && !schedule_boolean_monday0.Monday_0_19() && !schedule_boolean_monday0.Monday_0_20() &&
            !schedule_boolean_monday0.Monday_0_21() && !schedule_boolean_monday0.Monday_0_22() && !schedule_boolean_monday0.Monday_0_23() && !schedule_boolean_monday0.Monday_0_24()){
        start_time = 0;
        end_time = 1;
        schedule_boolean_monday0.Monday_0_1();
        mon_1.setText(databaseTimetable.Monday_Title(start_time, end_time));
        mon_1.setTextColor(Color.parseColor(databaseTimetable.Monday_Text_Color(start_time, end_time)));
        mon_1.setBackgroundColor(Color.parseColor(databaseTimetable.Monday_Text_BG_Color(start_time, end_time)));
        return 1;
    }
    //0 am - 2 hr.
    else if (!schedule_boolean_monday0.Monday_0_1() && schedule_boolean_monday0.Monday_0_2() && !schedule_boolean_monday0.Monday_0_3() && !schedule_boolean_monday0.Monday_0_4() && !schedule_boolean_monday0.Monday_0_5() &&
            !schedule_boolean_monday0.Monday_0_6() && !schedule_boolean_monday0.Monday_0_7()&& !schedule_boolean_monday0.Monday_0_8() && !schedule_boolean_monday0.Monday_0_9() && !schedule_boolean_monday0.Monday_0_10() &&
            !schedule_boolean_monday0.Monday_0_11() && !schedule_boolean_monday0.Monday_0_12() && !schedule_boolean_monday0.Monday_0_13() && !schedule_boolean_monday0.Monday_0_14() && !schedule_boolean_monday0.Monday_0_15() &&
            !schedule_boolean_monday0.Monday_0_16() && !schedule_boolean_monday0.Monday_0_17()&& !schedule_boolean_monday0.Monday_0_18() && !schedule_boolean_monday0.Monday_0_19() && !schedule_boolean_monday0.Monday_0_20() &&
            !schedule_boolean_monday0.Monday_0_21() && !schedule_boolean_monday0.Monday_0_22() && !schedule_boolean_monday0.Monday_0_23() && !schedule_boolean_monday0.Monday_0_24()){
        start_time = 0;
        end_time = 2;
        schedule_boolean_monday0.Monday_0_2();
        mon_1.setText(databaseTimetable.Monday_Title(start_time, end_time));
        mon_1.setTextColor(Color.parseColor(databaseTimetable.Monday_Text_Color(start_time, end_time)));
        mon_1.setBackgroundColor(Color.parseColor(databaseTimetable.Monday_Text_BG_Color(start_time, end_time)));
        mon_2.setBackgroundColor(Color.parseColor(databaseTimetable.Monday_Text_BG_Color(start_time, end_time)));
        return 2;
    }
    //0 am - 3 hr.
    else if (!schedule_boolean_monday0.Monday_0_1() && !schedule_boolean_monday0.Monday_0_2() && schedule_boolean_monday0.Monday_0_3() && !schedule_boolean_monday0.Monday_0_4() && !schedule_boolean_monday0.Monday_0_5() &&
            !schedule_boolean_monday0.Monday_0_6() && !schedule_boolean_monday0.Monday_0_7()&& !schedule_boolean_monday0.Monday_0_8() && !schedule_boolean_monday0.Monday_0_9() && !schedule_boolean_monday0.Monday_0_10() &&
            !schedule_boolean_monday0.Monday_0_11() && !schedule_boolean_monday0.Monday_0_12() && !schedule_boolean_monday0.Monday_0_13() && !schedule_boolean_monday0.Monday_0_14() && !schedule_boolean_monday0.Monday_0_15() &&
            !schedule_boolean_monday0.Monday_0_16() && !schedule_boolean_monday0.Monday_0_17()&& !schedule_boolean_monday0.Monday_0_18() && !schedule_boolean_monday0.Monday_0_19() && !schedule_boolean_monday0.Monday_0_20() &&
            !schedule_boolean_monday0.Monday_0_21() && !schedule_boolean_monday0.Monday_0_22() && !schedule_boolean_monday0.Monday_0_23() && !schedule_boolean_monday0.Monday_0_24()){
        start_time = 0;
        end_time = 3;
        schedule_boolean_monday0.Monday_0_3();
        mon_1.setText(databaseTimetable.Monday_Title(start_time, end_time));
        mon_1.setTextColor(Color.parseColor(databaseTimetable.Monday_Text_Color(start_time, end_time)));
        mon_1.setBackgroundColor(Color.parseColor(databaseTimetable.Monday_Text_BG_Color(start_time, end_time)));
        mon_2.setBackgroundColor(Color.parseColor(databaseTimetable.Monday_Text_BG_Color(start_time, end_time)));
        mon_3.setBackgroundColor(Color.parseColor(databaseTimetable.Monday_Text_BG_Color(start_time, end_time)));
        return 3;
    }

    return 99;
    }
}

This is a class that indicates Boolean variables这是一个 class 表示 Boolean 变量

public class Schedule_Boolean_Monday_0 {

    private Context mContext;
    private DatabaseTimetable databaseTimetable;

    public Schedule_Boolean_Monday_0(Context context){
        this.mContext = context;
    }

    public Boolean Monday_0_1(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,1);
        return !result.equals("");
    }

    public Boolean Monday_0_2(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,2);
        return !result.equals("");
    }

    public Boolean Monday_0_3(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,3);
        return !result.equals("");
    }

    public Boolean Monday_0_4(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,4);
        return !result.equals("");
    }

    public Boolean Monday_0_5(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,5);
        return !result.equals("");
    }

    public Boolean Monday_0_6(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,6);
        return !result.equals("");
    }

    public Boolean Monday_0_7(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,7);
        return !result.equals("");
    }

    public Boolean Monday_0_8(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,8);
        return !result.equals("");
    }

    public Boolean Monday_0_9(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,9);
        return !result.equals("");
    }

    public Boolean Monday_0_10(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,10);
        return !result.equals("");
    }

    public Boolean Monday_0_11(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,11);
        return !result.equals("");
    }

    public Boolean Monday_0_12(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,12);
        return !result.equals("");
    }

    public Boolean Monday_0_13(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,13);
        return !result.equals("");
    }

    public Boolean Monday_0_14(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,14);
        return !result.equals("");
    }

    public Boolean Monday_0_15(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,15);
        return !result.equals("");
    }

    public Boolean Monday_0_16(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,16);
        return !result.equals("");
    }

    public Boolean Monday_0_17(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,17);
        return !result.equals("");
    }

    public Boolean Monday_0_18(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,18);
        return !result.equals("");
    }

    public Boolean Monday_0_19(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,19);
        return !result.equals("");
    }

    public Boolean Monday_0_20(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,20);
        return !result.equals("");
    }

    public Boolean Monday_0_21(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,21);
        return !result.equals("");
    }

    public Boolean Monday_0_22(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,22);
        return !result.equals("");
    }

    public Boolean Monday_0_23(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,23);
        return !result.equals("");
    }

    public Boolean Monday_0_24(){
        databaseTimetable = new DatabaseTimetable(mContext);
        String result = databaseTimetable.Monday_Title(0,0);
        return !result.equals("");
    }
}

There are 24 Boolean variables in each if/else-if arguments.在每个 if/else-if arguments 中有 24 个 Boolean 变量。 I thought converting to switch methods might lead better performance for my app and if you have any ideas, I'd like to hear your advice.我认为转换为切换方法可能会为我的应用带来更好的性能，如果您有任何想法，我想听听您的建议。

2 个解决方案

解决方案1
 0  2020-04-09 00:12:23

Your problem is not the if statement, if statements are as efficient as they can get.您的问题不是if语句， if语句尽可能高效。 Your problem is accessing the database for every variable access, and this is what you should deal with.您的问题是为每个变量访问访问数据库，这是您应该处理的问题。

If I were you, I'd read all boolean variables once and then used those values to implement whatever logic you're trying to implement.如果我是你，我会读一遍所有 boolean 变量，然后使用这些值来实现你想要实现的任何逻辑。 The main point being, READ ONCE AND CACHE ALL YOU CAN .要点是， READ ONCE AND CACHE ALL YOU CAN 。

解决方案2
 0  2020-04-09 00:36:03

One of the core principles of writing good code is avoiding repetition .编写好代码的核心原则之一是避免重复。 In your case, I think trying to adhere to this principle might help.就您而言，我认为尝试遵守这一原则可能会有所帮助。

To expand on Lenik's answer, I think you would be best to first enclose your entire if statement in a check that first checks Monday_0_4 through Monday_0_24 .为了扩展 Lenik 的答案，我认为您最好先将整个if语句包含在首先检查Monday_0_4到Monday_0_24的检查中。 Something like this:像这样的东西：

if( !schedule_boolean_monday0.Monday_0_4() && !schedule_boolean_monday0.Monday_0_5() &&  
    !schedule_boolean_monday0.Monday_0_6() && !schedule_boolean_monday0.Monday_0_7()&& 
    !schedule_boolean_monday0.Monday_0_8() && !schedule_boolean_monday0.Monday_0_9() && 
    !schedule_boolean_monday0.Monday_0_10() && !schedule_boolean_monday0.Monday_0_11() && 
    !schedule_boolean_monday0.Monday_0_12() && !schedule_boolean_monday0.Monday_0_13() && 
    !schedule_boolean_monday0.Monday_0_14() && !schedule_boolean_monday0.Monday_0_15() && 
    !schedule_boolean_monday0.Monday_0_16() && !schedule_boolean_monday0.Monday_0_17()&& 
    !schedule_boolean_monday0.Monday_0_18() && !schedule_boolean_monday0.Monday_0_19() && 
    !schedule_boolean_monday0.Monday_0_20() && !schedule_boolean_monday0.Monday_0_21() && 
    !schedule_boolean_monday0.Monday_0_22() && !schedule_boolean_monday0.Monday_0_23() && 
    !schedule_boolean_monday0.Monday_0_24() ) {
    //your existing if statement here, but with the checks for Monday_0_4 through Monday_0_24 removed from each one
}

Secondly, just for the sake of nicer code, and bearing in mind I might not fully understand your code, I think you might be best redesigning your database check to the following:其次，只是为了更好的代码，并记住我可能不完全理解您的代码，我认为您最好将数据库检查重新设计为以下内容：

public Boolean Monday_0(int hour){
    databaseTimetable = new DatabaseTimetable(mContext);
    String result = databaseTimetable.Monday_Title(0,hour);
    return !result.equals("");
}

You could also further simplify your code by:您还可以通过以下方式进一步简化代码：

  • Putting one return value outside your if statements, returning end_time .在 if 语句outside放置一个返回值，返回end_time 。 end_time should be initialised to -1, which would double as the "error" return value (instead of 99). end_time应初始化为 -1，这将作为“错误”返回值的两倍（而不是 99）。
  • Moving these outside the if too, because they're called no matter which condition is true: (you'd need another nested if to make sure it's not called when Monday_0_1 is false)也将它们移到 if 之外，因为无论哪个条件为真，它们都会被调用：（您需要另一个嵌套的 if 以确保在 Monday_0_1 为假时不会调用它）
mon_1.setText(databaseTimetable.Monday_Title(start_time, end_time));
mon_1.setTextColor(Color.parseColor(databaseTimetable.Monday_Text_Color(start_time, end_time)));
mon_1.setBackgroundColor(Color.parseColor(databaseTimetable.Monday_Text_BG_Color(start_time, end_time)));
  • Performing your checks with a for loop, using the improved database check I mentioned earlier使用我之前提到的改进的数据库检查，使用for循环执行检查

Hope this helps!希望这可以帮助！

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