对自定义对象进行排序(C++/Java)

电玩女神 2022-08-06 00:25 237阅读 0赞

自定义了对象，如何按照自定对象中某一或多个元素对其进行排序呢？以下分别从C++和java对其进行实现。

**一：C++**

/*
    实现对自定义的对象类型进行排序(按照其中的元素)，首先将对象存放在vector中，然后利用algorithm库函数中的sort对其进行排序，需要重写排序函数以函数名
    作为函数指针作为sort的第三个参数
    */
    
    #include <iostream>
    #include <string>
    #include <algorithm>
    #include <vector>
    using namespace std;
    
    
    struct students{
    	int age;
    	string name;
    };
    
    void addStudents(vector<students> &vec, int age, string name){
    	students stu;
    	stu.age = age;
    	stu.name = name;
    	vec.push_back(stu);
    	
    }
    
    // 按照年龄进行排序 升序
    bool sortByAge(const students &s1, const students &s2){
    	return s1.age < s2.age;
    }
    
    
    // 先按照年龄进行排序 年纪一样 按照姓名排序
    bool sortByAll(const students &s1, const students &s2){
    	if(s1.age < s2.age) return true;
    	else if(s1.age > s2.age) return false;
    	else return s1.name < s2.name;
    }
    int main(){
    	vector<students> vec;
    	addStudents(vec, 20, "zhangming");
    	addStudents(vec, 20, "xiaoming");
    	addStudents(vec, 20, "xiaoming2");
    	addStudents(vec, 23, "xiaohong");
    	addStudents(vec, 22, "xiaofei");
    	addStudents(vec, 27, "xiaogang");
    	cout << "排序前:" << endl;
    	for(vector<students>::iterator iter = vec.begin(); iter != vec.end(); ++iter){
    		cout << (*iter).age << " " << (*iter).name << endl;
    	}
    	sort(vec.begin(), vec.end(), sortByAll);
    	cout << "排序后:" << endl;
    	for(vector<students>::iterator iter = vec.begin(); iter != vec.end(); ++iter){
    		cout << (*iter).age << " " << (*iter).name << endl;
    	}
    }

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**二：Java**

主函数sortClass.java：

package com.test.sort;
    
    import java.util.ArrayList;
    import java.util.Arrays;
    
    import com.zack.bean.Students;
    
    public class sortClass {
    	
    	
    	/*
    	 * ArrayList 中存储了自定义的对象类型， 然后通过toArray()转换为Object类型，再使用java.util.Arrays.sort进行排序
    	 * 注意的是排序要重新实现comparator接口进行，作为sort的第二个参数即myComparator对象
    	 */
    
    	static ArrayList<Students> arrayList = new ArrayList<Students>();
    	public static void addStudents(int age, String username){
    		
    		Students s = new Students(age, username);
    		arrayList.add(s);
    	}
    	
    	@SuppressWarnings("unchecked")
    	public static void main(String[] args) {
    		addStudents(20, "xiaoming");
    		addStudents(20, "zhangming");
    		addStudents(20, "xiaoming2");
    		addStudents(25, "xiaohong");
    		addStudents(23, "xiaogang");
    		addStudents(21, "xiaojie");
    		System.out.println("排序前:");
    		for(int i = 0; i < arrayList.size(); i++)
    		{
    			System.out.println(arrayList.get(i).getAge() + " ::" + arrayList.get(i).getUsername());
    		}
    		
    		System.out.println("降排序后:");
    		Object[] obj = arrayList.toArray();
    		Arrays.sort(obj, new myComparator());
    		
    		for(int i = 0; i < obj.length; i++)
    		{
    			System.out.println(obj[i]);
    		}
    	}
    
    }

myComparator.java:

package com.test.sort;
    
    import java.util.Comparator;
    
    import com.zack.bean.Students;
    
    public class myComparator implements Comparator{
    
    	@Override
    	public int compare(Object o1, Object o2) {
    		// TODO Auto-generated method stub
    	
    		Students s1 = (Students) o1;
    		Students s2 = (Students) o2;
    		if(s1.getAge() < s2.getAge())
    			return 1;
    		else if(s1.getAge() > s2.getAge())
    			return -1;
    		else return s1.getUsername().compareTo(s2.getUsername());
    	}
    
    }

Students.java:

package com.zack.bean;
    
    public class Students {
    	private int age;
    	private String username;
    	
    	public Students(int age, String username){
    		this.age = age;
    		this.username = username;
    	}
    	
    	public int getAge(){
    		return this.age;
    	}
    	public String getUsername(){
    		return this.username;
    	}
    	public String toString(){
    		return this.age + "::" + this.username;
    	}
    }

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[Center]: /images/20220806/5e0f77ea93c94703b8b7305bf851be39.png
[Center 1]: /images/20220806/5fa95be6cc1c40a7a9983e6509bcfa9d.png