单身狗要看完 ，帮你介绍对象 ----------------的比较

}

}

public static void main(String[] args) {
Student student1 = new Student(“拉塞尔”,29);
Student student2 = new Student(“亚历山大”,27);
Student[] students = {student1,student2};
Arrays.sort(students);
System.out.println(Arrays.toString(students));
}

###  二、自定义比较器，实现Comparator接口，重写compare()方法


####  或者使用匿名内部类，重写compare()方法



> 
> **排序为例（Arrays.sort）**  
>  源码
> 
> 
> 

public static <T> void sort(T[] a, Comparator<? super T> c) {
    if (c == null) {
        sort(a);
    } else {
        if (LegacyMergeSort.userRequested)
            legacyMergeSort(a, c);
        else
            TimSort.sort(a, 0, a.length, c, null, 0, 0);
    }
}

/\*\* To be removed in a future release. \*/
private static <T> void legacyMergeSort(T[] a, Comparator<? super T> c) {
    T[] aux = a.clone();
    if (c==null)
        mergeSort(aux, a, 0, a.length, 0);
    else
        mergeSort(aux, a, 0, a.length, 0, c);
}


private static void mergeSort(Object[] src,
                              Object[] dest,
                              int low, int high, int off,
                              Comparator c) {
    int length = high - low;

    // Insertion sort on smallest arrays
    if (length < INSERTIONSORT\_THRESHOLD) {
        for (int i=low; i<high; i++)
            for (int j=i; j>low && c.compare(dest[j-1], dest[j])>0; j--)
                swap(dest, j, j-1);  //交换操作， dest[j-1]是原来的，dest[j]是新增的
        return;
    }

> 
> **举例**
> 
> 
> 

class Student {
private String name;
private int age;

public Student(String name, int age) {
    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 String toString() {
    return "Student{" +
            "name='" + name + '\'' +
            ", age=" + age +
            '}';
}

}

> 
> 1.自定义比较器
> 
> 
> 

class AgeComparator implements Comparator{

@Override
public int compare(Student o1, Student o2) {
//o1是前面的，o2是后面的
//从小到大
    return o1.getAge()-o2.getAge();
//从大到小
// return o2.getAge()-o1.getAge();
}

}
class NameComparator implements Comparator{
@Override
public int compare(Student o1, Student o2) {
return o1.getName().compareTo(o2.getName());
}
}
public static void main1(String[] args) {
Student[] students = new Student[2];
students[0] = new Student(“yyds”, 18);
students[1] = new Student(“rlgl”, 20);
Arrays.sort(students, new NameComparator());
System.out.println(Arrays.toString(students));
}

> 
> 2. 匿名内部类
> 
> 
> 

public static void main(String[] args) {
Student[] students = new Student[2];
students[0] = new Student(“yyds”, 18);
students[1] = new Student(“rlgl”, 20);
Arrays.sort(students, new Comparator() {
@Override
public int compare(Student o1, Student o2) {
// 从小到大排
return o1.getAge() - o2.getAge();
}
});
System.out.println(Arrays.toString(students));
}

###  三、重写equals() 方法，比较相同与否



> 
> object类的equals()方法，若a是String类型，则调用String类的equals()方法
> 
> 
> **源码**
> 
> 
> 

public boolean equals(Object obj) {
    return (this == obj);
}

> 
> String类的equals方法  
>  **源码**
> 
> 
> 

public boolean equals(Object anObject) {
if (this == anObject) {
return true;
}
if (anObject instanceof String) {
String anotherString = (String)anObject;
int n = value.length;
if (n == anotherString.value.length) {
char v1[] = value;
char v2[] = anotherString.value;
int i = 0;
while (n-- != 0) {
if (v1[i] != v2[i])
return false;
i++;
}
return true;
}
}
return false;
}

![在这里插入图片描述](https://img-blog.csdnimg.cn/d6f1b0cbd25b41f39aa00f52ab1ae725.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBA5aiB5bCR5oC75Yag5Yab,size_10,color_FFFFFF,t_70,g_se,x_16)



> 
> **举例**
> 
> 
> 

class Player{
public String name;
public int age;
public Player(String name,int age) {
this.name = name;
this.age = age;
}

@Override
public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    Player player = (Player) o;
    return age == player.age &&
            Objects.equals(name, player.name);
}

@Override
public int hashCode() {
    return Objects.hash(name, age);
}

}
public class GuoQing {
public static void main(String[] args) {
Player player1 = new Player(“qiangzai”,18);
Player player2 = new Player(“qiangzai”,18);
//比较地址
System.out.println(player1 == player2);
//比较内容
System.out.println(player1.equals(player2));
}
}

**别等待，别遗憾，去经历，无需畏惧，反正这世界，我们只来一次**  
 ![在这里插入图片描述](https://img-blog.csdnimg.cn/feb77246683e45dd925aeffe815027a1.jpg?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBA5aiB5bCR5oC75Yag5Yab,size_20,color_FFFFFF,t_70,g_se,x_16)