JAvaオブジェクト配列の削除、比較器の2つの使用方法

         
      
Student.java
import java.util.Arrays;
import java.util.Scanner;

public class Student extends MyComparator implements Comparable<Student>
{
	int id;
	String name;
	String sex;
	int age;
	double score;

	Student()
	{	
	}
	public Student(int id, String name, String sex, int age ,double score) {
		super();
		this.id = id;
		this.name = name;
		this.sex = sex;
		this.age=age;
		this.score = score;
	}   
	@Override
	public String toString() {
		return "id：" + id + ",   ：" + name + ",   ：" + sex + " ,   ： " + age +  ",   " + score;
	}

	public void print(Student arr[])
	{ 
 		for(Student i:arr)
		{
			System.out.println(i);	
		}	
	}
	public Student[] add(Student arr[])
    {
		int count =arr.length;
	 Scanner sc=new Scanner(System.in);
	 Student stu=new Student();
	 System.out.println("     id：");
	 stu.id=sc.nextInt();
	 System.out.println("       ：");
	 stu.name=sc.next();
	 System.out.println("       ：");
	 stu.sex=sc.next();
	 System.out.println("       ：");
	 stu.age=sc.nextInt();
	 System.out.println("       ：");
	 stu.score=sc.nextDouble();
   	 if(count>=arr.length)
   	 {
   		 Student []arr1=Arrays.copyOf(arr, (arr.length+1));
   		 arr=arr1;//             ，    +1
   	 }
   	 arr[count]=stu;
	return arr;
    } 
    public static Student[] delete(Student arr[],int id)
    {
   	 for(int i=0;i<arr.length;i++)
   	 {
   		 if((arr[i].id)==(id))
   		 {
   			 for(int j=i;j<arr.length-1;j++)
   			 {
   				 arr[j]=arr[j+1];
   			 }
   			 Student []arr1=Arrays.copyOf(arr, arr.length-1);
   			 return arr1;
   		 }  
   	 }
		return arr;	 	 
    }
   
    public static Student[] set(Student arr[],int id)
    {
     Scanner sc=new Scanner(System.in);
     boolean y=true;
   	 for(int i=0;i<arr.length;i++)
   	 {
   		if((arr[i].id)==(id))
  		 {
   			y=false;
   		 System.out.println("          
1-id
2-  
3-  
4-  
5-  ");
   		  int p=sc.nextInt();
   			switch(p)
	         {
	             case 1:
	            	 System.out.println("      id：");
	            	 arr[i].id=sc.nextInt();
                 break;
	             case 2:  	 
	            	 System.out.println("        ：");
	            	 arr[i].name=sc.next();
	             break;
	             case 3:
	            	 System.out.println("        ：");
	    	         arr[i].sex=sc.next();
	    	     break;
	             case 4:
	            	 System.out.println("        ：");
	    	         arr[i].age=sc.nextInt();
	    	     break;
	             case 5:
	            	 System.out.println("        ：");
	    	         arr[i].score=sc.nextDouble();
	    	     break;
	         }
  		 }	
   	 }
   	 if(y==true)
	  {
		  System.out.println("      ");
	  }
   	 return arr;
    }
  public static void get(Student arr[],String str)
  {
	  boolean y=true;
	  for(int i=0;i<arr.length;i++)
	   	 {
	   		if(arr[i].name.equals(str)||(str.valueOf(arr[i].id).equals(str)))
	  		 {
	   			y=false;
	   		    System.out.println(arr[i]);
	  		 }
	   	 }
	  if(y==true)
 		{
 		 System.out.println("      ");
 		}
  }
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Student other = (Student) obj;
		if (id != other.id)
			return false;
		if (name == null) {
			if (other.name != null)
				return false;
		} else if (!name.equals(other.name))
			return false;
		return true;
	}
	
	public int compareTo(Student s) 
	  {
		if(this.id>s.id)
		{
			return 1;
		}
		if(this.id<s.id)
		{
			return -1;
		}
		return 0;
	  }	
}

Test.java
import java.util.Arrays;
import java.util.Scanner;

public class Test 
{
    public static void main(String[] args) 
    {
    	 Student []arr= {
    			 new Student(3,"  "," ",25,99.0),
    			 new Student(4,"  "," ",25,90.0),
    			 new Student(2,"  "," ",26,66.0),
    			 new Student(1,"  "," ",24,88.0)
    	  };
         Student stu=new Student();
 		while(true)
        {
	         System.out.println(""
	         		+ "1-        "
	         		+ "
2-      "
	         		+ "
3-      "
	         		+ "
4-      "
	         		+ "
5-      "
	         		+ "
6- id    "
	         		+ "
7-       "
	         		+ "
          ");
			Scanner sc=new Scanner(System.in);
	         int i=sc.nextInt();
	         switch(i)
	         {
	             case 1:
	            	 stu.print(arr);
	             break;
	             case 2:
	            	 arr=stu.add(arr);
	            	 stu.print(arr);
	             break;
	             case 3:
	            	 System.out.println("          id");
	    	         int j=sc.nextInt();
	            	 arr=Student.delete(arr, j);
	            	 stu.print(arr);
	            break;
	             case 4:
	            	 System.out.println("          id");
	    	         int k=sc.nextInt();
	            	 arr=Student.set(arr, k);
	            	 stu.print(arr);
	             break;
	             case 5:
	            	 System.out.println("          id   ");
	    	         String str=sc.next();
	            	 Student.get(arr,str);	 
	             break;
	             case 6:
	            	 Arrays.sort(arr);
	            	 stu.print(arr);
	             break;
	             case 7:
	            	 Arrays.sort(arr,new MyComparator());
	            	 stu.print(arr);
	             break;
	         }
	         System.out.println("    ");
	         String str=sc.next();
	         char a=str.charAt(0);
	         if(a=='n'||a=='N')
	         {
	        	 break;
	         }
	        	 
         }
	}
}

MyComparator.java
import java.util.Comparator;

public class MyComparator implements Comparator<Student>
{

	public int compare(Student stu1, Student stu2) 
	{
		if(stu1.sex.hashCode()>stu2.sex.hashCode())
		{
			return -1;
		}
		if(stu1.sex.hashCode()<stu2.sex.hashCode())
		{
			return 1;
		}
		return 0;
	}  
}