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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  1   2    java/ android/ performance/ android-studio/ if-statement

问题描述

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。

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。

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;
    }
}

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("");
    }
}

在每个 if/else-if arguments 中有 24 个 Boolean 变量。 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

您的问题不是if语句， if语句尽可能高效。 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。

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。 要点是， READ ONCE AND CACHE ALL YOU CAN 。

解决方案2
 0  2020-04-09 00:36:03

编写好代码的核心原则之一是避免重复。 就您而言，我认为尝试遵守这一原则可能会有所帮助。

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。 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
}

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("");
}

您还可以通过以下方式进一步简化代码：

  • 在 if 语句outside放置一个返回值，返回end_time 。 end_time应初始化为 -1，这将作为“错误”返回值的两倍（而不是 99）。
  • 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)));
  • 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

希望这可以帮助！

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