Question

我正在开发一个小型Java程序，该程序会向在我学校注册AP考试的电子邮件学生输出收据。代码看起来像这样。

// Create email text body for student who registered for an AP exam.

import java.util.Scanner;

class EmailText {

    public static void main(String args[]) {

        Scanner input = new Scanner(System.in);

        String first_name;
        String email;
        int numTests;
        char ch;
        char choice;
        int cost;

        System.out.print("Enter student first name: ");
        first_name = input.next();

        System.out.print("Enter student email: ");
        email = input.next();

        System.out.print("Enter number of tests ordered (1-9): ");
        numTests = input.nextInt();
        if(numTests < 10) {

            System.out.print("Did student qualify for fee waiver (y/n)? ");
            ch = input.next().charAt(0);

            if(ch == 'y') {
                cost = 5;
                int total = numTests * cost;

                System.out.println("** COPY/PASTE THIS DRAFT **");
                System.out.println("To: " + email);
                System.out.println("Subject: 2014 AP Test Receipt for " + first_name);
                System.out.println();
                System.out.println("Hi " + first_name + ",\n");
                System.out.println("Thank you for registering for the 2014 AP Exams!");
                System.out.println("According to our records, you ordered " + numTests + " tests.\n");
                System.out.println("Because you stated that you qualified for a fee waiver, " +
                        "each test will cost you $" + cost + ".");
                System.out.println("Your total cost is $" + cost + " * " + numTests +
                       " = $" + total + ".\n"); 
                System.out.println("Please submit your payment to the College Counseling Office ASAP.\nThank you.\n");
            }

            else if(ch == 'n') {
                cost = 89;
                int total = numTests * cost;

                System.out.println("** Copy/Paste this Draft **");
                System.out.println("To: " + email);
                System.out.println("Subject: 2014 AP Test Receipt for " + first_name);
                System.out.println();
                System.out.println("Hi " + first_name + ",\n");
                System.out.println("Thank you for registering for the 2014 AP Exams!");
                System.out.println("According to our records, you ordered " + numTests + " tests.");
                System.out.println("Because you stated that you qualified for a fee waiver, " +
                        "each test will cost you $" + cost + ".");
                System.out.println("Your total cost is $" + cost + " * " + numTests +
                       " = $" + total + ".\n"); 
                System.out.println("Please submit your payment to the College Counseling Office ASAP.\nThank you.\n");
            }
            } 
            else {
                System.out.println("Please start again.");
                return;
        }
    }
}

我遇到的问题是我在else和if块中重复相同的System.out.println（）体。相反，我想要做的是创建一个可以在每个块中调用的方法。

如果可能，我该如何做到这一点？

Answer 1

如果这是你的意思，那么你需要阅读基本的Java，我已经在代码示例中添加了你的方法，请阅读此链接以了解有关方法的更多信息：http://docs.oracle.com/javase/tutorial/java/javaOO/methods.html

请参阅Peter的回答以获取更多信息！

// Create email text body for student who registered for an AP exam.

import java.util.Scanner;

class EmailText {

    public static void main(String args[]) {

        int numTests, cost;
        String email, first_name;
        char ch;

        Scanner input = new Scanner(System.in);

        System.out.print("Enter student first name: ");
        first_name = input.next();

        System.out.print("Enter student email: ");
        email = input.next();

        System.out.print("Enter number of tests ordered (1-9): ");
        numTests = input.nextInt();
        if(numTests < 10) {

            System.out.print("Did student qualify for fee waiver (y/n)? ");
            ch = input.next().charAt(0);

            if(ch == 'y') {
                cost = 5;
                PrintStuff(numTests, cost, email, first_name, "qualified for a fee waiver, ");
            }
            else if(ch == 'n') {
                cost = 89;
                PrintStuff(numTests, cost, email, first_name, "did not qualify for a fee waiver, ");
            } else {
                System.out.println("Please start again.");
            }
        }
    }

    public static void PrintStuff(int numTests, int cost, String email, String first_name, String fw_status) {
        int total = numTests * cost;

        System.out.println("** COPY/PASTE THIS DRAFT **");
        System.out.println("To: " + email);
        System.out.println("Subject: 2014 AP Test Receipt for " + first_name);
        System.out.println();
        System.out.println("Hi " + first_name + ",\n");
        System.out.println("Thank you for registering for the 2014 AP Exams!");
        System.out.println("According to our records, you ordered " + numTests + " tests.\n");
        System.out.println("Because you stated that you " + fw_status +
                "each test will cost you $" + cost + ".");
        System.out.println("Your total cost is $" + cost + " * " + numTests +
               " = $" + total + ".\n"); 
        System.out.println("Please submit your payment to the Student Store ASAP.\nThank you.\n");
    }
}

Answer 2

不需要一个方法，只需要一些DRY重构：

if(ch == 'y' || ch == 'n') {
    cost = ch == 'y' ? 5 : 89;
    int total = numTests * cost;

    System.out.println("** COPY/PASTE THIS DRAFT **");
    System.out.println("To: " + email);
    System.out.println("Subject: 2014 AP Test Receipt for " + first_name);
    System.out.println();
    System.out.println("Hi " + first_name + ",\n");
    System.out.println("Thank you for registering for the 2014 AP Exams!");
    System.out.println("According to our records, you ordered " + numTests + " tests.\n");
    System.out.println("Because you stated that you qualified for a fee waiver, " +
            "each test will cost you $" + cost + ".");
    System.out.println("Your total cost is $" + cost + " * " + numTests +
           " = $" + total + ".\n"); 
    System.out.println("Please submit your payment to the College Counseling Office ASAP.\nThank you.\n");
} else {
    System.out.println("Please start again.");
    return;
}

Answer 3

创建一个类似这样的方法：

private String createOutput(int cost, String email, String first_name...)
{
    StringBuffer outputBuffer = new StringBuffer();
    outputBuffer.append("** Copy/Paste this Draft **\n");
    outputBuffer.append("To: " + email + "\n");
    outputBuffer.append("Subject: 2014 AP Test Receipt for " + first_name + "\n");
    outputBuffer.append("\n");
    ...

    return outputBuffer.toString();
}

然后您的IF语句将如下所示：

if(ch == 'y') {
    cost = 5;
    int total = numTests * cost;
    System.out.println(createOutput(cost, email, first_name, ...);
}
else if (ch == 'n') {
    cost = 89;
    int total = numTests * cost;
    System.out.println(createOutput(cost, email, first_name, ...);
}

Answer 4

您可以通过向此方法添加参数来实现此目的。一切都不能在一个if/else if块之间打印完全相同的和另一个else if块，您可以创建该方法的参数。然后从
你调用相同方法的不同块，但你传递不同的值
参数。

Answer 5

您可以在main之外创建另一个方法来打印重复的System.out.println 这个方法可能包含这样的参数

 public void print(total){
System.out.println("** Copy/Paste this Draft **");
                System.out.println("To: " + email);
                System.out.println("Subject: 2014 AP Test Receipt for " + first_name);
                System.out.println();
                System.out.println("Hi " + first_name + ",\n");
                System.out.println("Thank you for registering for the 2014 AP Exams!");
                System.out.println("According to our records, you ordered " + numTests + " tests.");
                System.out.println("Because you stated that you qualified for a fee waiver, " +
                        "each test will cost you $" + cost + ".");
                System.out.println("Your total cost is $" + cost + " * " + numTests +
                       " = $" + total + ".\n"); 
                System.out.println("Please submit your payment to the College Counseling Office ASAP.\nThank you.\n");


}

在您的主要内容中，您可以访问此方法或将其置于

之类的条件中

 if(ch == 'y') {
               cost = 5;
                int total = numTests * cost;
               print(total);

}

Answer 6

import static java.lang.System.out;

允许您简单地引用该代码，虽然通常被认为是一种不好的做法，仅适用于一次性程序。

只需保存对System.out的引用即可为您保存该部分

PrintStream out = System.out;
out.println( "hello" );

或者给自己写一个很好的速记方法

public static void print(String s){
     System.out.println(s);
     }

你必须为int，double等编写重载，否则你可以使用字符串连接

int x = 10;
print(x + "");

或者你的意思仅仅是那里的大块代码？在那种情况下......

public void printBlock(String email, String first_name, int numTests, int cost, int total){
                System.out.println("** COPY/PASTE THIS DRAFT **");
                System.out.println("To: " + email);
                System.out.println("Subject: 2014 AP Test Receipt for " + first_name);
                System.out.println();
                System.out.println("Hi " + first_name + ",\n");
                System.out.println("Thank you for registering for the 2014 AP Exams!");
                System.out.println("According to our records, you ordered " + numTests + " tests.\n");
                System.out.println("Because you stated that you qualified for a fee waiver, " +
                        "each test will cost you $" + cost + ".");
                System.out.println("Your total cost is $" + cost + " * " + numTests +
                       " = $" + total + ".\n"); 
                System.out.println("Please submit your payment to the College Counseling Office ASAP.\nThank you.\n");
    }

现在只需致电

if(thing){
printBlock("email","firstname",1,10,10);
}
else{
printBlock("email","othername",2,20,40);
}

或者其他什么。

创建并调用涉及多个System.out.println（）和变量的方法

6 个答案: