java使用自定义对象作为HashMap的key

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查找key的顺序:
1.调用hashCode()计算对象的HashCode，看是否存在表中
2.如果存在表中，则调用equals()判断对象是否相同

需要重写HashCode和equals方法，如果使用Eclipse就非常简单
直接右键->Source->Generate hashCode() and equals(),选择需要作为比较的字段即可

public class Student
{
	private String name;
	private int age;
	
	public Student(String name, int age) {
		super();
		this.name = name;
		this.age = age;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + age;
		result = prime * result + ((name == null) ? 0 : name.hashCode());
		return result;
	}

	@Override
	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 (age != other.age)
			return false;
		if (name == null) {
			if (other.name != null)
				return false;
		} else if (!name.equals(other.name))
			return false;
		return true;
	}
}