学步园

刚刚开始学习java, 路上的拦路虎还真不少。

在Java的vector中存储了一种用户自定义的数据类型，非基本数据类型，如何要删除，如何删除呢？这其中就牵扯到对象比较的问题。理解这个问题，其实用C++的指针来理解可能更好理解一些。

另外要重载用户自定义类型的 boolean equals(Object obj)这个方法，才能正确应用vector中相关和对象比较的方法。

package com.container;

public class student {
	private int code_;
	private String name_;
	private int grade_;

	public student(int code, String name, int grade) {
		code_ = code;
		name_ = name;
		grade_ = grade;
	}

	public student(student stu) {
		code_ = stu.getcode();
		name_ = stu.getname();
		grade_ = stu.getgrade();
	}

	public void output() {
		System.out.println("code=" + code_ + " name=" + name_ + " grade="
				+ grade_);
	}

	public int getcode() {
		return code_;
	}

	public String getname() {
		return name_;
	}

	public int getgrade() {
		return grade_;
	}

	public void setcode(int code) {
		code_ = code;
	}

	public void setname(String name) {
		name_ = name;
	}

	public void setgrade(int grade) {
		grade_ = grade;
	}
	
	
	public boolean equals(Object obj){
		student stu = (student)obj;
		if (code_ == stu.code_ && name_.equals(stu.name_) && grade_ == stu.grade_) 
		{
			return true;
		}
		return false;
	}
}

package com.container;

import java.util.Vector;

public class studentlist {

	Vector list = new Vector(10, 5);

	public studentlist() {
		list.clear();
	}

	public void add(student stu) {
		list.add(stu);
	}

	public void add(student stu, int index) {
		list.add(index, stu);
	}

	public boolean delete(student stu) {
		return list.remove(stu);
	}

	public boolean select(student stu) {
		if (list.indexOf(stu) == -1) {
			return false;
		}
		return true;
	}

	public void output() 
	{
		for (int i = 0; i < list.size(); i++)
		{
			((student) list.get(i)).output();
		}
	}
}

package com.softel;

import com.container.*;

public class test {
	public static void main(String[] args) {

		studentlist list = new studentlist();

		for (int i = 0; i < 5; i++) {
			student stu = new student(i, "wangxu" + i, i);
			list.add(stu);
		}

		student stu = new student(0, "wangxu0", 0);

		if (list.select(stu)) {
			System.out.println("true");
		} else {
			System.out.println("false");
		}

		list.delete(stu);

		if (list.select(stu)) {
			System.out.println("true");
		} else {
			System.out.println("false");
		}

		list.output();

	}
}