使用数组、List对对象内的某个属性进行排序的不同方法比较

朱雀 2021-12-24 09:25 140阅读 0赞

1.我们先创建一个People对象，存放排序的对象，代码如下：

public class People {
    	private String name;
    	private Integer age;
    	public String getName() {
    		return name;
    	}
    	public void setName(String name) {
    		this.name = name;
    	}
    	public Integer getAge() {
    		return age;
    	}
    	public void setAge(Integer age) {
    		this.age = age;
    	}
    	public People(String name, Integer age) {
    		super();
    		this.name = name;
    		this.age = age;
    	}
    	public People() {
    		super();
    	}
    	@Override
    	public String toString() {
    		return "Person [name=" + name + ", age=" + age + "]";
    	}	
    }

2.我们先使用数组进行排序，有两种方法，代码如下：

import java.util.Arrays;
    import java.util.Comparator;
    
    public class SortTest {
    
    	public static void main(String[] args) {
    		// TODO Auto-generated method stub
    		People[] persones = { new People("吴1", 25), new People("吴2", 15), new People("吴3", 45), new People("吴4", 35) };
    
    		// 正常方法(高性能)
    		for (int i = 0; i < persones.length; i++) {
    			for (int j = i; j < persones.length; j++) {
    				if (persones[i].getAge() < persones[j].getAge()) {// 升序
    					People temp = persones[i];
    					persones[i] = persones[j];
    					persones[j] = temp;
    				}
    			}
    		}
    
    		// 输出结果
    		for (People people : persones) {
    			System.out.println(people.toString());
    		}
    
    		System.out.println("---------------------------");
    
    		// 高级方法
    		Arrays.sort(persones, new Comparator<People>() {
    
    			@Override
    			public int compare(People o1, People o2) {
    				// TODO Auto-generated method stub
    				return o1.getAge() - o2.getAge();// 升序前面减后面，降序相反
    			}
    		});
    
    		// 输出结果
    		for (People people : persones) {
    			System.out.println(people.toString());
    		}
    		
    		System.out.println("---------------------------");
    
    		// 使用lambda表达式
    		Arrays.sort(persones, (People o1,People o2) ->{
    				return o2.getAge() - o1.getAge();// 降序
    		});
    
    		// 输出结果
    		for (People people : persones) {
    			System.out.println(people.toString());
    		}
    	}
    }

输出结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3Mjg0Nzk4_size_16_color_FFFFFF_t_70][]

第一种排序使用了两个循环，代码看起来臃肿，难以观看，第二种方法较好，写的也快，第三种是在第二种的基础上再加上lambda表达式写的，这样子的代码看起来更清爽

3.这是List,原理和数组一样，代码如下：

import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.Collections;
    import java.util.Comparator;
    import java.util.List;
    
    public class SortTest {
    
    	public static void main(String[] args) {
    		// TODO Auto-generated method stub
    		List<People> persones = new ArrayList<>();
    		persones.add(new People("吴1", 25));
    		persones.add(new People("吴2", 45));
    		persones.add(new People("吴3", 35));
    		persones.add(new People("吴4", 15));
    
    		// 正常方法
    		Collections.sort(persones, new Comparator<People>() {
    
    			@Override
    			public int compare(People o1, People o2) {
    				// TODO Auto-generated method stub
    				return o1.getAge() - o2.getAge();// 升序前面减后面，降序相反
    			}
    		});
    
    		// 输出结果
    		for (People people : persones) {
    			System.out.println(people.toString());
    		}
    		
    		System.out.println("---------------------------");
    
    		// 使用lambda表达式
    		Collections.sort(persones, (People o1,People o2) ->{
    				return o2.getAge() - o1.getAge();// 降序
    		});
    
    		// 输出结果
    		for (People people : persones) {
    			System.out.println(people.toString());
    		}
    	}
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3Mjg0Nzk4_size_16_color_FFFFFF_t_70]: /images/20211223/df0ff69cd501495b9d84c16bf0667563.png