创建和调用涉及多个 System.out.println() 和变量的方法答案

【问题标题】：Create and call method that involves multiple System.out.println() and variables创建和调用涉及多个 System.out.println() 和变量的方法
【发布时间】：2014-01-14 22:53:57
【问题描述】：

我正在开发一个小型 Java 程序，该程序会向在我学校注册 AP 考试的学生发送收据。代码如下所示。

// 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() 主体。相反，我想做的是创建一个可以在每个块中调用的方法。

如果可能，我该怎么做？

【问题讨论】：

标签： java string methods

【解决方案1】：

如果这是您的意思，那么您需要阅读基本 Java，我已在代码示例中添加了您的方法，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

更多信息也请参见彼得的回答！

// 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");
    }
}

【讨论】：

澄清（有人发表评论然后删除） - 我相信操作员正在询问如何使用一种方法来保存重复代码，仅此而已。如果我错了，我很乐意更新我的答案:)
这段代码有错误。请纠正他们。例如，在 PrintStuff() 中未定义 first_name。
@Zaphod42 - 谢谢。重新安装了我的机器，只有notepad++用于编码atm ... :)
更新的代码，请取消投票 ;)... 或者随意投票！ :-D
谢谢。我现在还在学习 Java，还没有创建新方法。这回答了我的问题。

【解决方案2】：

不需要方法，只是一些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;
}

【讨论】：

虽然我已经选择了我接受的答案，但我必须承认这个更胜一筹。是什么 ”？： ;”叫什么？
@JohnJ.Kim 它被称为三元运算符：docs.oracle.com/javase/tutorial/java/nutsandbolts/op2.html
@JohnJ.Kim 三元运算符只是执行 if/else 的一种更简洁的方式。在这种情况下，它与if (ch == 'y') cost = 5; else cost = 89;具有相同的效果。
@Bohemian 不过你的代码只有一件事。我的原始代码上的两个文本之间的区别在于“有资格获得费用减免”这一短语。还有一个“没有资格获得费用减免”。如果我将它设置为一个变量，它如何适合这里？
您的问题在任何地方都没有“不符合条件”的文本 - y 和 n 的两个输出文本都是相同的。 ch == 'n' 的时候你想要“没有”吗？

【解决方案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();
}

那么您的 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, ...);
}

【讨论】：

【解决方案4】：

您可以在打印重复的 System.out.println 的 main 之外创建另一个方法而且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");


}

在您的主目录中，您可以访问此方法或将其放入您的条件中，例如

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

}

【讨论】：

first_name 未为 print() 定义。除了总计之外，您还需要其他参数。 Total 没有定义，所以这是一个语法错误。
哦，是的，我忘了输入总计和其他参数的数据类型，但只要他了解流程..没关系

【解决方案5】：

您可以通过向该方法添加参数来完成此操作。一切
在 if/else if 块之间打印的内容不完全相同
和另一个else if 块，您为该方法创建一个参数。然后从
调用相同方法但传递不同值的不同块
用于参数。

【讨论】：

【解决方案6】：

import static java.lang.System.out;

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

只需保存对 System.out 的引用即可为您节省该部分

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);
     }

您必须为 int、double 等编写重载，或者您可以使用字符串连接

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

或者你的意思只是为了你的大块代码？那样的话……

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");
    }

现在打电话

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

或其他。

【讨论】：