使用lambdas的Java控制台菜单

我正在学习如何用Java创建一个基本的控制台菜单。有人告诉我，用lambda's做这件事会更有效率。这里的代码在没有lambda的情况下可以正常工作，但是我想知道如何修改它，以便可以使用lambda的方法将方法添加到menu类中

另外，为什么使用lambda会使其更好/更高效？或者它只是让代码更容易阅读

以下是课程：

可运行界面

@FunctionalInterface
public interface Runnable {
    public void run();
}

选秀班

public class ChoicePair<String, Runnable> {
    private String text;
    private Runnable funcint;

    public ChoicePair(String t, Runnable fi) {
        this.text = t;
        this.funcint = fi;
    }

    public void setText(String t) {this.text = t;}
    public void setFI(Runnable fi) {this.funcint = fi;}
    public String getText() {return this.text;}
    public Runnable getFI() {return this.funcint;}

}

import java.util.ArrayList;
import java.util.Scanner;

public class Menu implements Runnable {

    private String title;
    private ArrayList<ChoicePair> choices;
    public Scanner scan = new Scanner(System.in);
    public Menu(String title) {
        this.title = title;
        choices = new ArrayList<ChoicePair>();
    }

    @Override
    public void run() {
        int choiceInt = -1;
        while(choiceInt != 0) {
            System.out.println(title + ":");
            int x = 1;
            for (ChoicePair cur : choices) {
                System.out.println("[" + x + "]: " + cur.getText());
                x++;
            }
            if (title == "Main Menu")
                System.out.println("[0]: EXIT");
            else
                System.out.println("[0]: Back");
            System.out.println(">\t");
            choiceInt = getInt();
            act(choiceInt);
        }
    }
    public void addPair(ChoicePair addition) {
        choices.add(addition);
    }

    public int getInt() {
        return scan.nextInt();
    }

    public void act(int choiceInt) {
        if(choiceInt == 0)
            return;
        if(choiceInt < 0 || choiceInt > choices.size()) {
            System.out.println("Incorrect input.");
            return;
        }
        int choicePos = choiceInt - 1;
        ((Runnable)choices.get(choicePos).getFI()).run();
    }

}

import java.util.*;

public class Application {
    public static Scanner scan = new Scanner(System.in);
    public static void main(String[] args) {
        Menu mainMenu = new Menu("Main Menu");

        //Create runnables for setting mean types...
        Runnable setMean1 = new Runnable() {
            @Override
            public void run() {
                meanCalculator.setType(1);
                System.out.println("Mean type set to Arithmetic.");
            }
        };
        Runnable setMean2 = new Runnable() {
            @Override
            public void run() {
                meanCalculator.setType(2);
                System.out.println("Mean type set to Geometric...");
            }
        };
        Runnable setMean3 = new Runnable() {
            @Override
            public void run() {
                meanCalculator.setType(3);
                System.out.println("Mean type set to Harmonic...");
            }
        };
        //Create mean-setting menu and choicepairs and populate.
        Menu setMean = new Menu("Set Mean Type");
        ChoicePair mean1 = new ChoicePair("Arithmetic", setMean1);
        ChoicePair mean2 = new ChoicePair("Geometric", setMean2);
        ChoicePair mean3 = new ChoicePair("Harmonic", setMean3);
        setMean.addPair(mean1);
        setMean.addPair(mean2);
        setMean.addPair(mean3);
        mainMenu.addPair(new ChoicePair("Set Mean Type", setMean));

        //Create runnables for array setting...
        Runnable addValues = new Runnable() {
            @Override
            public void run() {
                ArrayList<Double> additionArrayList = new ArrayList<Double>();
                String input = null;
                int x = 0;
                System.out.print("Enter values to add to set, or '-1' to complete entry.\n> ");
                while (input != "-1") {
                    input = scan.nextLine();
                    if (Double.parseDouble(input) == -1.0D)
                        break;
                    additionArrayList.add(Double.parseDouble(input));
                }
                System.out.println("Break detected.");
                double[] additions = new double[additionArrayList.size()];
                for(double d: additionArrayList) {
                    additions[x] = d;
                    x++;
                }
                meanCalculator.addValues(additions);
            }
        };
        Runnable clearSet = new Runnable() {
            @Override
            public void run() {
                meanCalculator.clearSet();
            }
        };
        Runnable removeN = new Runnable() {
            @Override
            public void run() {
                System.out.print("Enter number of elements to remove from end\n> ");
                int toRemove = scan.nextInt();
                meanCalculator.removeN(toRemove);
            }
        };
        Runnable displaySet = new Runnable() {
            @Override
            public void run() {
                meanCalculator.display();
            }
        };
        ChoicePair add = new ChoicePair("Add values to Array", addValues);
        ChoicePair clear = new ChoicePair("Clear Array", clearSet);
        ChoicePair remove = new ChoicePair("Remove N elements", removeN);
        ChoicePair display = new ChoicePair("Display Array", displaySet);
        Menu arrayOptions = new Menu("Array Options");
        arrayOptions.addPair(add);
        arrayOptions.addPair(clear);
        arrayOptions.addPair(remove);
        arrayOptions.addPair(display);
        mainMenu.addPair(new ChoicePair("Array Options", arrayOptions));

        //Create runnable for calculate-mean function...
        Runnable calcMean = new Runnable() {
            @Override
            public void run() {
                double mean = meanCalculator.calcMean();
                String type = meanCalculator.getType();
                System.out.println(type + " mean for current array = " + mean);
            }
        };
        ChoicePair calculate = new ChoicePair("Calculate Mean", calcMean);
        mainMenu.addPair(calculate);



        //Run the main menu
        mainMenu.run();
    }
}

public class ChoicePair{
私有字符串文本；
私有可运行functint；
公共选秀节目（t字串，可运行fi）{
this.text=t；
this.funcint=fi；
}
public void setText（字符串t）{this.text=t；}
public void setFI（Runnable fi）{this.funcint=fi；}
公共字符串getText（）{返回this.text；}
public Runnable getFI（）{返回this.funcint；}
}

菜单类

public class ChoicePair<String, Runnable> {
    private String text;
    private Runnable funcint;

    public ChoicePair(String t, Runnable fi) {
        this.text = t;
        this.funcint = fi;
    }

    public void setText(String t) {this.text = t;}
    public void setFI(Runnable fi) {this.funcint = fi;}
    public String getText() {return this.text;}
    public Runnable getFI() {return this.funcint;}

}

import java.util.ArrayList;
import java.util.Scanner;

public class Menu implements Runnable {

    private String title;
    private ArrayList<ChoicePair> choices;
    public Scanner scan = new Scanner(System.in);
    public Menu(String title) {
        this.title = title;
        choices = new ArrayList<ChoicePair>();
    }

    @Override
    public void run() {
        int choiceInt = -1;
        while(choiceInt != 0) {
            System.out.println(title + ":");
            int x = 1;
            for (ChoicePair cur : choices) {
                System.out.println("[" + x + "]: " + cur.getText());
                x++;
            }
            if (title == "Main Menu")
                System.out.println("[0]: EXIT");
            else
                System.out.println("[0]: Back");
            System.out.println(">\t");
            choiceInt = getInt();
            act(choiceInt);
        }
    }
    public void addPair(ChoicePair addition) {
        choices.add(addition);
    }

    public int getInt() {
        return scan.nextInt();
    }

    public void act(int choiceInt) {
        if(choiceInt == 0)
            return;
        if(choiceInt < 0 || choiceInt > choices.size()) {
            System.out.println("Incorrect input.");
            return;
        }
        int choicePos = choiceInt - 1;
        ((Runnable)choices.get(choicePos).getFI()).run();
    }

}

import java.util.*;

public class Application {
    public static Scanner scan = new Scanner(System.in);
    public static void main(String[] args) {
        Menu mainMenu = new Menu("Main Menu");

        //Create runnables for setting mean types...
        Runnable setMean1 = new Runnable() {
            @Override
            public void run() {
                meanCalculator.setType(1);
                System.out.println("Mean type set to Arithmetic.");
            }
        };
        Runnable setMean2 = new Runnable() {
            @Override
            public void run() {
                meanCalculator.setType(2);
                System.out.println("Mean type set to Geometric...");
            }
        };
        Runnable setMean3 = new Runnable() {
            @Override
            public void run() {
                meanCalculator.setType(3);
                System.out.println("Mean type set to Harmonic...");
            }
        };
        //Create mean-setting menu and choicepairs and populate.
        Menu setMean = new Menu("Set Mean Type");
        ChoicePair mean1 = new ChoicePair("Arithmetic", setMean1);
        ChoicePair mean2 = new ChoicePair("Geometric", setMean2);
        ChoicePair mean3 = new ChoicePair("Harmonic", setMean3);
        setMean.addPair(mean1);
        setMean.addPair(mean2);
        setMean.addPair(mean3);
        mainMenu.addPair(new ChoicePair("Set Mean Type", setMean));

        //Create runnables for array setting...
        Runnable addValues = new Runnable() {
            @Override
            public void run() {
                ArrayList<Double> additionArrayList = new ArrayList<Double>();
                String input = null;
                int x = 0;
                System.out.print("Enter values to add to set, or '-1' to complete entry.\n> ");
                while (input != "-1") {
                    input = scan.nextLine();
                    if (Double.parseDouble(input) == -1.0D)
                        break;
                    additionArrayList.add(Double.parseDouble(input));
                }
                System.out.println("Break detected.");
                double[] additions = new double[additionArrayList.size()];
                for(double d: additionArrayList) {
                    additions[x] = d;
                    x++;
                }
                meanCalculator.addValues(additions);
            }
        };
        Runnable clearSet = new Runnable() {
            @Override
            public void run() {
                meanCalculator.clearSet();
            }
        };
        Runnable removeN = new Runnable() {
            @Override
            public void run() {
                System.out.print("Enter number of elements to remove from end\n> ");
                int toRemove = scan.nextInt();
                meanCalculator.removeN(toRemove);
            }
        };
        Runnable displaySet = new Runnable() {
            @Override
            public void run() {
                meanCalculator.display();
            }
        };
        ChoicePair add = new ChoicePair("Add values to Array", addValues);
        ChoicePair clear = new ChoicePair("Clear Array", clearSet);
        ChoicePair remove = new ChoicePair("Remove N elements", removeN);
        ChoicePair display = new ChoicePair("Display Array", displaySet);
        Menu arrayOptions = new Menu("Array Options");
        arrayOptions.addPair(add);
        arrayOptions.addPair(clear);
        arrayOptions.addPair(remove);
        arrayOptions.addPair(display);
        mainMenu.addPair(new ChoicePair("Array Options", arrayOptions));

        //Create runnable for calculate-mean function...
        Runnable calcMean = new Runnable() {
            @Override
            public void run() {
                double mean = meanCalculator.calcMean();
                String type = meanCalculator.getType();
                System.out.println(type + " mean for current array = " + mean);
            }
        };
        ChoicePair calculate = new ChoicePair("Calculate Mean", calcMean);
        mainMenu.addPair(calculate);



        //Run the main menu
        mainMenu.run();
    }
}

import java.util.ArrayList；
导入java.util.Scanner；
公共类菜单实现可运行{
私有字符串标题；
私人ArrayList选择；
公共扫描仪扫描=新扫描仪（System.in）；
公共菜单（字符串标题）{
this.title=标题；
choices=newarraylist（）；
}
@凌驾
公开募捐{
int choiceInt=-1；
while（choiceInt！=0）{
System.out.println（标题+“：”）；
int x=1；
for（ChoicePair cur:选项）{
System.out.println（“[”+x+“]：“+cur.getText（））；
x++；
}
如果（标题==“主菜单”）
System.out.println（“[0]：退出”）；
其他的
System.out.println（“[0]：Back”）；
System.out.println（“>\t”）；
choiceInt=getInt（）；
行动（选择）；
}
}
公共无效添加对（ChoicePair添加）{
选择。添加（添加）；
}
公共int getInt（）{
返回scan.nextInt（）；
}
公共无效法案（内部选择）{
如果（choiceInt==0）
返回；
if（choiceInt<0 | | choiceInt>choices.size（））{
System.out.println（“输入错误”）；
返回；
}
int choicePos=choiceInt-1；
（（Runnable）choices.get（choicePos.getFI（））.run（）；
}
}

平均计算器类（包含使用的方法）

公共类计算器{
私有静态双[]值；
私有静态int类型；
公共计算机（）{
}
公共静态无效设置值（双[]输入）{
values=input.clone（）；
}
公共静态void addvalue（双[]加法）{
如果（值==null）{
value=addition.clone（）；
返回；
}
double[]temp=新的double[values.length+addition.length]；
int-y；
对于（y=0；y

应用程序（主类）

import java.util.*；
公共类应用程序{
公共静态扫描仪扫描=新扫描仪（System.in）；
公共静态void main（字符串[]args）{
菜单主菜单=新菜单（“主菜单”）；
//创建用于设置平均类型的可运行项。。。
Runnable setMean1=新的Runnable（）{
@凌驾
公开募捐{
设置类型（1）；
System.out.println（“平均类型设置为算术”）；
}
};
Runnable setMean2=新的Runnable（）{
@凌驾
公开募捐{
平均值计算器.setType（2）；
System.out.println（“平均类型设置为几何…”）；
}
};
朗恩