异常处理与文本IO 习题12_24&12_25

12_24:创建大的数据集：创建一个具有1000行的数据文件。文件中的每行包含了一个教职员工的姓、名、级别以及薪水，第i行的教职员工的姓和名为FristNamei 和LastNamei。级别随机产生为assistant、associate、full。薪水为随机产生的数字，并且小数点后保留两位数字。对于助理教授而言，薪水应该在50000到80000的范围内，对于副教授为60000到110000。对于正教授为75000到130000。保存文件为Salary.txt.

package Pe12_24;import java.io.File;import java.io.PrintWriter;public class Exception12_24 {    public static void main(String[] args) throws Exception {        String strGardeName = null;        StringBuilder sb1 = new StringBuilder();        File tagartFile = new File(args[0]);        try (PrintWriter pw = new PrintWriter(tagartFile);) {            for (int i = 1; i <= 1000; i++) {                sb1.append("FristName" + i + " LastName" + i);                strGardeName = getGradeName((int) (Math.random() * 2 + 1));                sb1.append(" "+strGardeName);                sb1.append(" "+getSalary(strGardeName));                pw.println(sb1.toString());                sb1.delete(0, sb1.length());            }        }    }    //隨機產生教職員工級別    public static String getGradeName(int i) {        String strName = null;        if (i > 3 || i < 1) {            System.out.println("Uage:getGarde Error.");            System.exit(1);        }        switch (i) {        case 1:            return strName = "assistant";        case 2:            return strName = "associate";        case 3:            return strName = "full";        }        return strName;    }//隨機產生教職員工薪水，返回整數的字符串形式。    public static String getSalary(String gardeName) {        String strSalary = null;        double salary = 0;        if (!(gardeName.equalsIgnoreCase("assistant") || gardeName.equalsIgnoreCase("associate")                || gardeName.equalsIgnoreCase("full"))) {            System.out.println("Uage: getSalary Error");            System.exit(2);        }        if (gardeName.equalsIgnoreCase("assistant")) {            salary = Math.random() * 30000 + 50000;        } else if (gardeName.equalsIgnoreCase("associate")) {            salary = Math.random() * 50000 + 60000;        } else if (gardeName.equalsIgnoreCase("full")) {            salary = Math.random() * 55000 + 75000;        }        strSalary = String.valueOf(salary);        System.out.println(strSalary);        int index = strSalary.indexOf('.');        strSalary = strSalary.substring(0, index + 3);        return strSalary;    }}

**总结：
1、在写入文本的过程中，是使用了StringBuilder来处理字符串，主要就是因为StringBuilder在处理字符串时比较方便。
2、在随机产生教职员工级别的判断上，是采用了Math.random()的方法来随机产生‘1’、‘2’、‘3’来判断返回教职员工的级别。
3、在根据教职员工的级别来随机产生工资薪水的方法上是采用了String.equalsIgnoreCase()方法来判定教职员工的类别，从而使用Math.random()来随机产生规定范围内的工资薪水。**

12_25:一个大学将其教职员工的薪水发布在http://cs.strong.edu/liang/Salary.txt中。文件中的每行包含一个教职员工的姓、名、级别以及薪水。编写一个程序，分别显示助理教授、副教授、正教授，所有教职员工各个类别的总薪水，以及上诉类别的平均薪水。

package Pe12_25;import java.net.URL;import java.util.Scanner;public class Exception12_25 {    public static void main(String[] args) throws Exception {        double salary_assistant = 0;        int count_assistant = 0;        double salary_associate = 0;        int count_associate = 0;        double salary_full = 0;        int count_full = 0;        double salary_quantity = 0;        URL StringURL = new URL("http://cs.armstrong.edu/liang/data/Salary.txt");        String string_line = null;        try (Scanner input = new Scanner(StringURL.openStream());) {            while (input.hasNext()) {                string_line = input.nextLine();                //分隔字符串                String[] strings = string_line.split(" ");                //將字符串數組最後一項表示工資薪水的轉化成整數。                salary_quantity = Double.valueOf(strings[strings.length - 1]);                //對各個級別的工資和人數進行統計。                if (strings[strings.length - 2].equalsIgnoreCase("assistant")) {                    salary_assistant += salary_quantity;                    count_assistant++;                } else if (strings[strings.length - 2].equalsIgnoreCase("associate")) {                    salary_associate += salary_quantity;                    count_associate++;                } else if (strings[strings.length - 2].equalsIgnoreCase("full")) {                    salary_full += salary_quantity;                    count_full++;                }string_line = null;            }            System.out.printf("Assistant,count is %d, sum_salary is %.2f,average_salary:%.2f",count_assistant,salary_assistant,salary_assistant/count_assistant);            System.out.println();            System.out.printf("Accocite,count is %d, sum_salary is %.2f,average_salary:%.2f",count_associate,salary_associate,salary_associate/count_associate);            System.out.println();                       System.out.printf("Assistant,count is %d, sum_salary is %.2f,average_salary:%.2f",count_full,salary_full,salary_full/count_full);            System.out.println();            }    }}

*总结：
1、在读取一行字符串时，分别取出字符串中单独的字符串，使用String.split()以空格作为分隔标志，然后再对单独的字符串进行处理。*