java equals函数

java中所有类都是Object的子类，Object中实现了equals方法，使用时一般要对其进行重载。

不进行重载时

public class JavaTest
{
	public static void main(String[] args)
	{
		boolean result;
		Student stu1=new Student("cjc",24);
		Student stu2=new Student("cjc",24);
		result=stu1.equals(stu2);
		if(result)
		{
			System.out.println("是同一个人！");
		}
		else
		{
			System.out.println("不是同一个人！");
		}
	}	
}

class Student extends Object
{
	private String name;
	private int age;

	Student(String str,int num)
	{
		name=str;
		age=num;
	}
｝

进行重载后

public class JavaTest
{
	public static void main(String[] args)
	{
		boolean result;
		Student stu1=new Student("cjc",24);
		Student stu2=new Student("cjc",24);
		result=stu1.equals(stu2);
		if(result)
		{
			System.out.println("是同一个人！");
		}
		else
		{
			System.out.println("不是同一个人！");
		}
	}	
}

class Student extends Object
{
	private String name;
	private int age;

	Student(String str,int num)
	{
		name=str;
		age=num;
	}

	public boolean equals(Object o)
	{
		boolean result=false;

		if(o instanceof Student)
		{
			Student stu=(Student)o;
			if(stu.name.equals(this.name) && this.age==stu.age)
			{
				result=true;
			}
		}
		
		return result;
	}	
}

需要注意的是String类已经对equals进行了重载，所以程序中stu.name.equals(this.name)才可以这样使用