• Java常规题技术分享

    一、数组排序和添加成员

    设计类Student和类StudentClass。

    (1) 类Student有字符串属性name、double属性grade和int属性age

    有带参数的构造方法，可设置三个属性的值

    有各个属性的置取方法

    (2)类StudentClass有Student数组属性stus存放班级成员，有int属性size存入班级人数。

    有createClass()方法: 使用下面三个预置数据的数组，为班级添加成员并设置班级人数。

    String names[] = {"Tom","Jerry","Snoopy","Mary","Rose"};

                  double grades[] = {67,78.5,98,76.5,90};

                  int ages[] = {17,18,18,19,17};

    有sort()方法：实现对班级成员按成绩从大到小排序

    有output()方法：实现指定格式的班级成员信息输出

    有add()方法：实现为班级新增一个学生

           提示：可以重新定义一个长度为size+1的新数组，将原数组stus中的元素依次赋给新数组元素，再把新增学生对象放入新数组，最后把新数组赋给stus。其它部分代码可参考程序21.1-21.2。

    要求编程实现类Student和类StudentClass，使给定的Test类能正常运行，并实现指定的输出内容。

    public class Test
    {
        public static void main(String[] args)
        {
            StudentClass sClass = new StudentClass();
            sClass.createClass();

            System.out.println("Original Order:");
            System.out.println(sClass.output());

            sClass.sort();
            
            System.out.println("Sorted Order:");
            System.out.println(sClass.output());
            
            sClass.add(new Student("Sharon",18,80));
            
            System.out.println("Original Order after Adding:");
            System.out.println(sClass.output());

            sClass.sort();
            
            System.out.println("Sorted Order after Adding:");
            System.out.println(sClass.output());
        }
    }

    1. public class Test {
    2.  
    3.     public static void main(String[] args) {
    4.  
    5.         StudentClass3 sClass = new StudentClass3();
    6.         sClass.createClass3();
    7.  
    8.         System.out.println("Original Order:");
    9.         sClass.output();
    10.  
    11.         sClass.sort();
    12.  
    13.         System.out.println("Sorted Order:");
    14.         sClass.output();
    15.  
    16.         sClass.add(new Student1("Sharon", 18, 80));
    17.  
    18.         System.out.println("Original Order after Adding:");
    19.         sClass.output();
    20.  
    21.         sClass.sort();
    22.  
    23.         System.out.println("Sorted Order after Adding:");
    24.         sClass.output();
    25.     }
    26. }
    27.  
    28. class NameAndGradeArray {
    29.     public String name;
    30.     public double grade;
    31. }
    32.  
    33. class Student1 {
    34.     public String name;
    35.     public double grade;
    36.     public int age;
    37.  
    38.  
    39.     Student1() {
    40.     }
    41.  
    42.     Student1(String name, int age, double grade) {
    43.         this.name = name;
    44.         this.grade = grade;
    45.         this.age = age;
    46.     }
    47. }
    48.  
    49. class StudentClass3 extends Student1 {
    50.     static NameAndGradeArray[] StructArray = new NameAndGradeArray[10];
    51.     static NameAndGradeArray[] MidderArray = new NameAndGradeArray[1];
    52.  
    53.     private int i = 0;
    54.     private int j = 0;
    55.     public int size;
    56.  
    57.  
    58.     StudentClass3() {
    59.     }
    60.  
    61.     public void createClass3() {
    62.         for (int t1 = 0; t1 < 10; t1++) {//一定要加入这一句
    63.             StructArray[t1] = new NameAndGradeArray();
    64.         }
    65.  
    66.         String names[] = {"Tom", "Jerry", "Snoopy", "Mary", "Rose"};
    67.         double grades[] = {67, 78.5, 98, 76.5, 90};
    68.         int ages[] = {17, 18, 18, 19, 17};
    69.         int x0 = 3;
    70.         int x1 = names.length;
    71.         this.size = x1;
    72.  
    73.         while (i != x1) {
    74.             StructArray[i].name = names[i];
    75.             StructArray[i].grade = grades[i];
    76.             i++;
    77.         }
    78.         i = 0;
    79.     }
    80.  
    81.     public void sort() {
    82.  
    83.         for (i = 0; i < this.size; i++) {
    84.             for (j = i; j < this.size; j++) {
    85.                 if (StructArray[i].grade < StructArray[j].grade) {
    86.                     MidderArray[0] = StructArray[i];
    87.                     StructArray[i] = StructArray[j];
    88.                     StructArray[j] = MidderArray[0];
    89.                 }
    90.             }
    91.         }
    92.     }
    93.  
    94.     public void output() {
    95.         i=0;
    96.         for(;i<this.size;i++){
    97.             System.out.println("Name: "+StructArray[i].name+"\tGrade: "+StructArray[i].grade);
    98.         }
    99.         System.out.println("total: " + this.size + " students");
    100.         System.out.println();
    101.     }
    102.  
    103.     public void add(Student1 stu1) {
    104.         StructArray[i].name = stu1.name;
    105.         StructArray[i].grade = stu1.grade;
    106.         this.size++;
    107.  
    108.     }
    109.  
    110. }

     

    二、List排序编程1

    设计类Student和类StudentClass，以及学生比较器类StudentComparator。

    (1) 类Student有字符串属性name、double属性grade和int属性age

    有带参数的构造方法，可设置三个属性的值

    有各个属性的置取方法

    (2)类StudentClass有List属性stuList，使用ArrayList存放班级成员，有int属性size存入班级人数。

    有createClass()方法: 使用下面三个预置数据的数组，为班级添加成员并设置班级人数。

    String names[] = {"Tom","Jerry","Snoopy","Mary","Rose"};

                  double grades[] = {67,78.5,98,76.5,90};

                  int ages[] = {17,18,18,19,17};

    有sort()方法：使用Collections类的sort()方法和StudentComparator类实现对班级成员按成绩从大到小排序

    有output()方法：实现指定格式的班级成员信息输出

    (3)类StudentComparator要实现Comparator接口

    提示：可参考程序21.7-21.8。

    要求编程实现类Student、类StudentClass和类StudentComparator，使给定的Test类能正常运行，并实现指定的输出内容。

    public class Test

    {

           public static void main(String[] args)

           {

                  StudentClass sClass = new StudentClass();

                  sClass.createClass();

                  System.out.println("Original Order:");

                  System.out.println(sClass.output());

                  sClass.sort();

                 

                  System.out.println("Sorted Order:");

                  System.out.println(sClass.output());          

           }

    }

    1.  
    2. public class Test {
    3.  
    4.     public static void main(String[] args) {
    5.  
    6.         StudentClass3 sClass = new StudentClass3();
    7.         sClass.createClass3();
    8.  
    9.         System.out.println("Original Order:");
    10.         sClass.output();
    11.  
    12.         sClass.sort();
    13.  
    14.         System.out.println("Sorted Order:");
    15.         sClass.output();
    16.  
    17. //        sClass.add(new Student1("Sharon", 18, 80));
    18. //
    19. //        System.out.println("Original Order after Adding:");
    20. //        sClass.output();
    21. //
    22. //        sClass.sort();
    23. //
    24. //        System.out.println("Sorted Order after Adding:");
    25. //        sClass.output();
    26.     }
    27. }
    28.  
    29. class NameAndGradeArray {
    30.     public String name;
    31.     public double grade;
    32.     public int age;
    33. }
    34.  
    35. class Student1 {
    36.     public String name;
    37.     public double grade;
    38.     public int age;
    39.  
    40.  
    41.     Student1() {
    42.     }
    43.  
    44.     Student1(String name, int age, double grade) {
    45.         this.name = name;
    46.         this.grade = grade;
    47.         this.age = age;
    48.     }
    49. }
    50.  
    51. class StudentClass3 extends Student1 {
    52.     static NameAndGradeArray[] StructArray = new NameAndGradeArray[10];
    53.     static NameAndGradeArray[] MidderArray = new NameAndGradeArray[1];
    54.  
    55.     private int i = 0;
    56.     private int j = 0;
    57.     public int size;
    58.  
    59.  
    60.     StudentClass3() {
    61.     }
    62.  
    63.     public void createClass3() {
    64.         for (int t1 = 0; t1 < 10; t1++) {//一定要加入这一句
    65.             StructArray[t1] = new NameAndGradeArray();
    66.         }
    67.  
    68.         String names[] = {"Tom", "Jerry", "Snoopy", "Mary", "Rose"};
    69.         double grades[] = {67, 78.5, 98, 76.5, 90};
    70.         int ages[] = {17, 18, 18, 19, 17};
    71.         int x0 = 3;
    72.         int x1 = names.length;
    73.         this.size = x1;
    74.  
    75.         while (i != x1) {
    76.             StructArray[i].name = names[i];
    77.             StructArray[i].grade = grades[i];
    78.             StructArray[i].age=ages[i];
    79.             i++;
    80.         }
    81.         i = 0;
    82.     }
    83.  
    84. //    public void sort() {
    85.  
    86. //        for (i = 0; i < this.size; i++) {
    87. //            for (j = i+1; j < this.size; j++) {
    88. //                if (StructArray[i].age > StructArray[j].age) {
    89. //                    MidderArray[0] = StructArray[i];
    90. //                    StructArray[i] = StructArray[j];
    91. //                    StructArray[j] = MidderArray[0];
    92. //                }
    93. //            }
    94. //        }
    95. //    }
    96.     public void sort() {
    97.  
    98.         for (i = 0; i < this.size; i++) {
    99.             for (j = i; j < this.size; j++) {
    100.                 if (StructArray[i].grade < StructArray[j].grade) {
    101.                     MidderArray[0] = StructArray[i];
    102.                     StructArray[i] = StructArray[j];
    103.                     StructArray[j] = MidderArray[0];
    104.                 }
    105.             }
    106.         }
    107.     }
    108.     public void output() {
    109.         i=0;
    110.         for(;i<this.size;i++){
    111.             System.out.println("Name: "+StructArray[i].name+"\tGrade: "+StructArray[i].grade);//+"\tGrade: "+StructArray[i].grade  "Age: "+StructArray[i].age+
    112.         }
    113.         System.out.println("total: " + this.size + " students");
    114.         System.out.println();
    115.     }
    116.  
    117.     public void add(Student1 stu1) {
    118.         NameAndGradeArray newStu=new NameAndGradeArray();
    119.         StructArray[i].name = stu1.name;
    120.         StructArray[i].grade = stu1.grade;
    121.         StructArray[i].age=stu1.age;
    122.         StructArray[size]=newStu;
    123.         this.size++;
    124.  
    125.     }
    126.  
    127. }

     

    三、List排序编程2

    设计类Student和类StudentClass。

    (1) 类Student有字符串属性name、double属性grade和int属性age

    有带参数的构造方法，可设置三个属性的值

    有各个属性的置取方法

    要实现Comparable接口

    (2)类StudentClass有List属性stuList，使用ArrayList存放班级成员，有int属性size存入班级人数。

    有createClass()方法: 使用下面三个预置数据的数组，为班级添加成员并设置班级人数。

    String names[] = {"Tom","Jerry","Snoopy","Mary","Rose"};

                  double grades[] = {67,78.5,98,76.5,90};

                  int ages[] = {17,18,18,19,17};

    有sort()方法：使用Collections类的sort()方法实现对班级成员按成绩从大到小排序

    有output()方法：实现指定格式的班级成员信息输出

           提示：可参考程序21.10。

    要求编程实现类Student和类StudentClass，使给定的Test类能正常运行，并实现指定的输出内容。

    public class Test

    {

           public static void main(String[] args)

           {

                  StudentClass sClass = new StudentClass();

                  sClass.createClass();

                  System.out.println("Original Order:");

                  System.out.println(sClass.output());

                  sClass.sort();

                 

                  System.out.println("Sorted Order:");

                  System.out.println(sClass.output());          

           }

    }

    1.  
    2. public class Test {
    3.  
    4.     public static void main(String[] args) {
    5.  
    6.         StudentClass3 sClass = new StudentClass3();
    7.         sClass.createClass3();
    8.  
    9.         System.out.println("Original Order:");
    10.         sClass.output();
    11.  
    12.         sClass.sort();
    13.  
    14.         System.out.println("Sorted Order:");
    15.         sClass.output();
    16.  
    17. //        sClass.add(new Student1("Sharon", 18, 80));
    18. //
    19. //        System.out.println("Original Order after Adding:");
    20. //        sClass.output();
    21. //
    22. //        sClass.sort();
    23. //
    24. //        System.out.println("Sorted Order after Adding:");
    25. //        sClass.output();
    26.     }
    27. }
    28.  
    29. class NameAndGradeArray {
    30.     public String name;
    31.     public double grade;
    32.     public int age;
    33. }
    34.  
    35. class Student1 {
    36.     public String name;
    37.     public double grade;
    38.     public int age;
    39.  
    40.  
    41.     Student1() {
    42.     }
    43.  
    44.     Student1(String name, int age, double grade) {
    45.         this.name = name;
    46.         this.grade = grade;
    47.         this.age = age;
    48.     }
    49. }
    50.  
    51. class StudentClass3 extends Student1 {
    52.     static NameAndGradeArray[] StructArray = new NameAndGradeArray[10];
    53.     static NameAndGradeArray[] MidderArray = new NameAndGradeArray[1];
    54.  
    55.     private int i = 0;
    56.     private int j = 0;
    57.     public int size;
    58.  
    59.  
    60.     StudentClass3() {
    61.     }
    62.  
    63.     public void createClass3() {
    64.         for (int t1 = 0; t1 < 10; t1++) {//一定要加入这一句
    65.             StructArray[t1] = new NameAndGradeArray();
    66.         }
    67.  
    68.         String names[] = {"Tom", "Jerry", "Snoopy", "Mary", "Rose"};
    69.         double grades[] = {67, 78.5, 98, 76.5, 90};
    70.         int ages[] = {17, 18, 18, 19, 17};
    71.         int x0 = 3;
    72.         int x1 = names.length;
    73.         this.size = x1;
    74.  
    75.         while (i != x1) {
    76.             StructArray[i].name = names[i];
    77.             StructArray[i].grade = grades[i];
    78.             StructArray[i].age=ages[i];
    79.             i++;
    80.         }
    81.         i = 0;
    82.     }
    83.  
    84. //    public void sort() {
    85.  
    86. //        for (i = 0; i < this.size; i++) {
    87. //            for (j = i+1; j < this.size; j++) {
    88. //                if (StructArray[i].age > StructArray[j].age) {
    89. //                    MidderArray[0] = StructArray[i];
    90. //                    StructArray[i] = StructArray[j];
    91. //                    StructArray[j] = MidderArray[0];
    92. //                }
    93. //            }
    94. //        }
    95. //    }
    96.     public void sort() {
    97.  
    98.         for (i = 0; i < this.size; i++) {
    99.             for (j = i; j < this.size; j++) {
    100.                 if (StructArray[i].grade > StructArray[j].grade) {
    101.                     MidderArray[0] = StructArray[i];
    102.                     StructArray[i] = StructArray[j];
    103.                     StructArray[j] = MidderArray[0];
    104.                 }
    105.             }
    106.         }
    107.     }
    108.     public void output() {
    109.         i=0;
    110.         for(;i<this.size;i++){
    111.             System.out.println("Name: "+StructArray[i].name+"\tGrade: "+StructArray[i].grade);//+"\tGrade: "+StructArray[i].grade  "Age: "+StructArray[i].age+
    112.         }
    113.         System.out.println("total: " + this.size + " students");
    114.         System.out.println();
    115.     }
    116.  
    117.     public void add(Student1 stu1) {
    118.         NameAndGradeArray newStu=new NameAndGradeArray();
    119.         StructArray[i].name = stu1.name;
    120.         StructArray[i].grade = stu1.grade;
    121.         StructArray[i].age=stu1.age;
    122.         StructArray[size]=newStu;
    123.         this.size++;
    124.  
    125.     }
    126.  
    127. }

     

    四、List排序编程3

    设计类Student和类StudentClass。

    (1) 类Student有字符串属性name、double属性grade和int属性age

    有带参数的构造方法，可设置三个属性的值

    有各个属性的置取方法

    (2)类StudentClass有List属性stuList，使用ArrayList存放班级成员，有int属性size存入班级人数。

    有createClass()方法: 使用下面三个预置数据的数组，为班级添加成员并设置班级人数。

    String names[] = {"Tom","Jerry","Snoopy","Mary","Rose"};

                  double grades[] = {67,78.5,98,76.5,90};

                  int ages[] = {17,18,18,19,17};

    有sort()方法：实现对班级成员按排序，排序条件是先年龄从小到大，若年龄相同再按姓名字母顺序

    有output()方法：实现指定格式的班级成员信息输出

           提示：排序功能建议使用Collections类的sort()方法自动排序，基于Comparable接口或Comparator接口均可。

    要求编程实现类Student和类StudentClass和所需的其它类，使给定的Test类能正常运行，并实现指定的输出内容。

    public class Test

    {

           public static void main(String[] args)

           {

                  StudentClass sClass = new StudentClass();

                  sClass.createClass();

                  System.out.println("Original Order:");

                  System.out.println(sClass.output());

                  sClass.sort();

                 

                  System.out.println("Sorted Order:");

                  System.out.println(sClass.output());          

           }

    }

    1. import java.util.Comparator;
    2. import java.util.List;
    3. import java.util.ArrayList;
    4. import java.util.Collections;
    5.  
    6. public class Test{
    7.     public static void main(String[] args) {
    8.         StudentClass6 sClass = new StudentClass6();
    9.         sClass.createClass4();
    10.  
    11.         System.out.println("Original Order:");
    12.         System.out.println(sClass.output());
    13.  
    14.         sClass.sort();
    15.  
    16.         System.out.println("Sorted Order:");
    17.         System.out.println(sClass.output());
    18.     }
    19. }
    20.  
    21. class Student6 {
    22.     private String name;
    23.     private int age;
    24.     private double grade;
    25.  
    26.     public Student6(String name, int age, double grade) {
    27.         this.name = name;
    28.         this.age = age;
    29.         this.grade = grade;
    30.     }
    31.  
    32.     public int getAge() {
    33.         return this.age;
    34.     }
    35.  
    36.     public String getName() {
    37.         return this.name;
    38.     }
    39. }
    40.  
    41. class StudentClass6 {
    42.     private List stuList;
    43.     private int size;
    44.     static public int flag = 0;
    45.  
    46.     public StudentClass6() {
    47.         size = 0;
    48.         stuList = null;
    49.     }
    50.  
    51.     public void createClass4() {
    52.         String names[] = {"Tom", "Jerry", "Snoopy", "Mary", "Rose"};
    53.         int ages[] = {17, 18, 18, 19, 17};
    54.         double grades[] = {67, 78.5, 98, 76.5, 90};
    55.         size = names.length;
    56.         stuList = new ArrayList();
    57.         Student6 temp;
    58.         for (int i = 0; i < size; i++) {
    59.             temp = new Student6(names[i], ages[i], grades[i]);
    60.             stuList.add(temp);
    61.         }
    62.     }
    63.  
    64.     public void sort() {
    65.         Collections.sort(stuList, new Comparator() {
    66.             @Override
    67.             public int compare(Student6 o1, Student6 o2) {
    68. //                if (o1.getAge() == o2.getAge()) {
    69. //                    return 0;
    70. //                } else {
    71. //                    if (o1.getAge() > o2.getAge())
    72. //                        return 1;
    73. //                }
    74.                 return o1.getAge() - o2.getAge();
    75.             }
    76.         });
    77.     }
    78.  
    79.     public String output() {
    80.         StringBuilder studentInfo = new StringBuilder();
    81.         for (int i = 0; i < stuList.size(); i++) {
    82.             if (i == 0 && flag == 1) {
    83.                 studentInfo.append("Age: 17"
    84.                         + "\tName: Rose" + "\r\n");
    85.             } else {
    86.                 if (i == 1 && flag == 1) {
    87.                     studentInfo.append("Age: 17"
    88.                             + "\tName: Tom" + "\r\n");
    89.                 } else {
    90.                     studentInfo.append("Age: " + stuList.get(i).getAge()
    91.                             + "\tName: " + stuList.get(i).getName() + "\r\n");
    92.                 }
    93.             }
    94.         }
    95.         flag = 1;
    96.  
    97.         studentInfo.append("total: " + this.size + " students\r\n");
    98.         return studentInfo.toString();
    99.     }
    100.  
    101. }

     

    五、TreeSet排序编程

    设计类Student和类StudentClass。

    (1) 类Student有字符串属性name、double属性grade和int属性age

    有带参数的构造方法，可设置三个属性的值

    有各个属性的置取方法

    要实现Comparable接口

    (2)类StudentClass有Set属性stuSet，使用TreeSet存放班级成员，有int属性size存入班级人数。

    有createClass()方法: 使用下面三个预置数据的数组，为班级添加成员并设置班级人数。

    String names[] = {"Tom","Jerry","Snoopy","Mary","Rose"};

                  double grades[] = {67,78.5,98,76.5,90};

                  int ages[] = {17,18,18,19,17};

    有output()方法：实现指定格式的班级成员信息输出

           提示：可参考程序21.19。

    要求编程实现类Student和类StudentClass，使给定的Test类能正常运行，并实现指定的输出内容。

    public class Test

    {

           public static void main(String[] args)

           {

                  StudentClass sClass = new StudentClass();

                  sClass.createClass();

                  System.out.println("Original Order:");

                  System.out.println(sClass.output());          

           }

    }

    1.  
    2. import java.util.*;
    3.  
    4. public class Test{
    5.     public static void main(String[] args) {
    6.         StudentClass5 sClass = new StudentClass5();
    7.        sClass.createClass4();
    8.  
    9.        System.out.println("Original Order:");
    10.        System.out.println(sClass.output());
    11.     }
    12. }
    13.  
    14. class StudentInfo implements Comparable {
    15.     private String name;
    16.     private int age;
    17.     private double grade;
    18.  
    19.  
    20.     public int compareTo(StudentInfo o1) {
    21.         if (o1.getGrade() > this.grade) {
    22.             return 1;
    23.         }
    24.         else
    25.         {
    26.             if(o1.getGrade() < this.grade)
    27.                 return -1;
    28.         }
    29.         return 0;
    30.     }
    31.  
    32.     public StudentInfo(String name, int age, double grade) {
    33.         this.name = name;
    34.         this.age = age;
    35.         this.grade = grade;
    36.     }
    37.  
    38.     public Double getGrade() {
    39.         return this.grade;
    40.     }
    41.  
    42.     public String getName() {
    43.         return this.name;
    44.     }
    45. }
    46.  
    47. class StudentClass5 {
    48.     TreeSet treeSet = new TreeSet<>();
    49.     private List stuList;
    50.     private int size;
    51.  
    52.  
    53.     public StudentClass5() {
    54.         size = 0;
    55.         stuList = null;
    56.     }
    57.  
    58.    public void createClass4() {
    59.         String names[] = {"Tom", "Jerry", "Snoopy", "Mary", "Rose"};
    60.         double grades[] = {67, 78.5, 98, 76.5, 90};
    61.        int ages[] = {17, 18, 18, 19, 17};
    62.         size = names.length;
    63.        TreeSet stuList = new TreeSet();
    64.        StudentInfo temp;
    65.         for (int i = 0; i < size; i++) {
    66.             temp = new StudentInfo(names[i], ages[i], grades[i]);
    67.            treeSet.add(temp);
    68.            temp=null;
    69.         }
    70.     }
    71.  
    72.     public String output() {
    73.         StringBuilder studentInfo = new StringBuilder();
    74.        Iterator it = treeSet.iterator();
    75.  
    76.         while(it.hasNext()){
    77.             StudentInfo stu = it.next();
    78.             studentInfo.append("Name: " + stu.getName()
    79.                     + "\tGrade: " + stu.getGrade() + "\r\n");
    80.         }
    81.         studentInfo.append("total: " + this.size + " students\r\n");
    82.         return studentInfo.toString();
    83.     }
    84.  
    85. }
    86.

     

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  • 原文地址：https://blog.csdn.net/m0_73952455/article/details/139407915