class.java

用Java做的一个学生考试分析程序

/*
 * Class.java
 *
 * Created on 2007年12月12日, 下午6:16
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package 考试成绩分析程序;
import java.io.*;
/**
 *
 * @author drawen
 */
public class Class implements java.io.Serializable{
    public static final String CLASS_FILE="classFile.dat";
    private int grade;
    private String major;
    private int classNumber;
    private int studentNumber=0;
    private Student students[];
    /** Creates a new instance of Class */
    public Class() {        
        setGrade(2005);
        setMajor("计算机科学与技术");
        setClassNumber(3);
        setStudentNumber(0);
        students=new Student[20];
    }
    public Class(int grade,String major,int classNumber,
            int studentNumber,Student students[]){
        setGrade(grade);
        setMajor(major);
        setClassNumber(classNumber);
        setStudentNumber(0);
        this.students=new Student[20];
        int i;
        for(i=0;i<studentNumber;i++)
            addStudent(students[i]);
    }
    public void setGrade(int grade){
        this.grade=grade;
    }
    public int getGrade(){
        return grade;
    }
    public void setMajor(String major){
        this.major=major;
    }
    public String getMajor(){
        return major;
    }
    public void setClassNumber(int classNumber){
        this.classNumber=classNumber;
    }
    public int getClassNumber(){
        return classNumber;
    }
    public void setStudentNumber(int studentNumber){
        this.studentNumber=studentNumber;
    }
    public int getStudentNumber(){
        return studentNumber;
    }
    public Student[] getStudents(){
        return students;
    }
    public Student findStudent(Student student){
        int i;
        for(i=0;i<studentNumber;i++){
            if(students[i].equals(student))
                return students[i];
        }
        return null;
    }
    public boolean addStudent(Student newStudent){
        if(findStudent(newStudent)!=null)
            return false;
        if(studentNumber>=students.length){
            int i;
            Student []temp=new Student[2*students.length+1];
            for(i=0;i<students.length;i++)
                temp[i]=students[i];        
            students=temp;
        }
        students[studentNumber++]=newStudent;
        return true;
    }
    public boolean removeStudent(Student student){
        int i;
        for(i=0;i<studentNumber;i++){
            if(!students[i].equals(student))
                continue;
            if(i<studentNumber){
                studentNumber--;
                for(;i<studentNumber;i++)
                    students[i]=students[i+1];
                return true;
            }
        }
        return false;
    }
    public boolean equals(Object o){
        Class temp=(Class)o;
        return ((temp.grade==grade)&&(temp.major.equals(major))&&(temp.classNumber==classNumber));
    }
    public boolean saveToFile(){
        MainWindow.initDataFile(CLASS_FILE);
        DataInputStream input;
        DataOutputStream output;  
        int grade,classNumber,studentNumber;
        String major;
        Student student=new Student();
        try{
            input=new DataInputStream(new FileInputStream(CLASS_FILE));
            while(input.available()>0){
                grade=input.readInt();
                major=input.readUTF();
                classNumber=input.readInt();
                studentNumber=input.readInt();
                for(int i=0;i<studentNumber;i++){
                    student.setId(input.readLong());
                    student.setName(input.readUTF());
                }
                if((grade==this.grade)&&(classNumber==this.classNumber)&&(major.equals(this.major))){
                    input.close();
                    return false;
                }            
            }
            input.close();
            output=new DataOutputStream(new FileOutputStream(CLASS_FILE,true));
            output.writeInt(this.grade);
            output.writeUTF(this.major);
            output.writeInt(this.classNumber);
            output.writeInt(this.studentNumber);
            for(int i=0;i<this.studentNumber;i++){
                output.writeLong(students[i].getId());
                output.writeUTF(students[i].getName());
            }
            output.close();
            return true;
        }catch(Exception e){
            return false;
        }        
    }    
    public static Class queryFromFile(int grade,String major,int classNumber){
        MainWindow.initDataFile(CLASS_FILE);
        Class temp=new Class();
        DataInputStream input;  
        Student student;
        try{
            input=new DataInputStream(new FileInputStream(CLASS_FILE));
            while(input.available()>0){                
                temp.setGrade(input.readInt());
                temp.setMajor(input.readUTF());
                temp.setClassNumber(input.readInt());
                int studentNumber=input.readInt();
                temp.setStudentNumber(0);
                for(int i=0;i<studentNumber;i++){
                    student=new Student();
                    student.setId(input.readLong());
                    student.setName(input.readUTF());
                    temp.addStudent(student);
                }
                if((grade==temp.getGrade())&&(major.equals(temp.getMajor()))&&
                        (classNumber==temp.getClassNumber())){
                    input.close();
                    return temp;
                }
            }
            input.close();
            return null;
        }catch(Exception e){            
            return null;
        }
    }   
    public static Class[] loadFile(){
        Class[] array=new Class[20];
        int count=0;
        MainWindow.initDataFile(CLASS_FILE);
        Student student;
        DataInputStream input;
        try{
            input=new DataInputStream(new FileInputStream(CLASS_FILE));
            while(input.available()>0){
                if(count>=array.length){
                    Class[] temp=new Class[array.length*2];
                    for(int i=0;i<array.length;i++)
                        temp[i]=array[i];
                    array=temp;
                }
                array[count]=new Class();
                array[count].setGrade(input.readInt());
                array[count].setMajor(input.readUTF());
                array[count].setClassNumber(input.readInt());
                array[count].setStudentNumber(0);
                int num=input.readInt();
                for(int i=0;i<num;i++){
                    student=new Student();
                    student.setId(input.readLong());
                    student.setName(input.readUTF());
                    array[count].addStudent(student);
                }
                count++;
            }
            input.close();
            return array;
        }catch(Exception e){
            return null;
        }
    }
}