使用equals()方法

Question

所以我不确定为什么以下代码返回"它们不相等".从检查中它应该返回"他们是平等的".谁能帮我吗？先感谢您.

public class BenAndLiam {
public static void main(String[] args){
    String[] name = new String[2];
    name[0] = "Liam";
    name[1] = "Short";
    int[] marks = new int[3];
    marks[0] = 90;
    marks[1] = 50;
    marks[2] = 70;

    //make students
    Student Liam = new Student(1111, name, marks);
    Student Ben = new Student(1111, name, marks);

    //print Liam's info
    System.out.println(Liam.getId() + " " + Liam.getName()[0] + " " + 
    Liam.getName()[1] + " " + Liam.getMarks()[0] + " " + Liam.getMarks()[1] +
    " " + Liam.getMarks()[2]);
    System.out.println(Ben.getId() + " " + Ben.getName()[0] + " " + 
            Ben.getName()[1] + " " + Ben.getMarks()[0] + " " + Ben.getMarks()[1] +
            " " + Ben.getMarks()[2]);

    //check for equality
    if(Ben.equals(Liam))
        System.out.println("They're equal");
    else System.out.println("They're not equal");
    }
}

我的学生代码:

public class Student {
//The aspects of a student
private int id;
private String name[];
private int marks[];


//Constructor 1

public Student(int id, String name[]){
    this.id = id;
    this.name = name;
}

//Constructor 2
public Student(int id, String name[], int marks[]){
    setId(id);
    setName(name);
    setMarks(marks);
}

//accessor for id
public int getId(){
    return id;
}

//accessor for name
public String getName()[]{
    return name;
}

//accessor for marks
public int getMarks()[]{
    return marks;
}

//Mutator for id
public void setId(int id){
    this.id = id;
}
//mutator for name
public void setName(String name[]){
    this.name = name;
}
//Mutator for marks
public void setMarks(int marks[]){
    this.marks = marks;
}

}

根据事物的外观,我需要在我的Student类中使用equals()？

更新:我通过将此代码添加到我的Student类中来实现它:

public boolean equals(Student otherstudent){
    return ((id == otherstudent.id) && (name.equals(otherstudent.name)
            && (marks == otherstudent.marks)));
}

干杯啦!

Answer 1

您应该equals() 在Student类中重写该方法.

请更喜欢阅读:在Java中覆盖equals和hashCode时应该考虑哪些问题？

Answer 2

默认情况下,Object.equals()检查两个变量是否指向同一对象 - 同一内存空间中的一个实例.您有两个具有相同数据的不同对象.您需要覆盖.equals()方法以将对象的内容相互比较而不是默认值,以比较内存地址.

如果您覆盖equals(),请确保也覆盖hashCode().阅读Objectjavadoc中两种方法的合同,并确保遵循它,否则您的程序可能会出现异常,特别是如果您使用Collections API.