JAVA排序(二) Comparator接口

接着说关于Comparator接口，

java.util Interface Comparator<T>(该泛型指定的是被比较的类)，使用该接口不需要在待比较类进行比较操作，即在不修改源码的情况下进行比较（如代码交付后），

与Comparable相比稍微复杂，但是还是很方便~~

首先是待比较类，这里是一个记录温度与湿度的为了与上面做区分，在这里叫EnvironmentForms类：

 

public class EnvironmentForms {
	/**温度*/
	private float temp;
	/**湿度*/
	private float hum;
	public float getTemp() {
		return temp;
	}
	public void setTemp(float temp) {
		this.temp = temp;
	}
	public float getHum() {
		return hum;
	}
	public void setHum(float hum) {
		this.hum = hum;
	}
	/**
	 * 无参构造
	 */
	public EnvironmentForms(){}
	/**
	 * 有参构造
	 * @param temp 温度
	 * @param hum 湿度
	 */
	public EnvironmentForms(float temp, float hum) {
		super();
		this.temp = temp;
		this.hum = hum;
	}
	@Override
	public String toString() {
		return "EnvironmentForm [温度=" + temp + ", 湿度=" + hum + "]\n";
	}
}

在不修改此类的情况下，还是对温度进行降序排列，当温度相等湿度降序排列，

 

首先写一个比较规则类实现Comparator接口，

实现compare int compare(T o1,T o2)与equals boolean equals(Object obj)（该方法这里没有复写），代码如下：

 

import java.util.Comparator;
public class EnvironmentComparator implements Comparator<EnvironmentForms> {
	@Override
	public int compare(EnvironmentForms env1, EnvironmentForms env2) {
		//大于所给温度则返回-1
		if(env1.getTemp()>env2.getTemp()){
			return -1;
		}else if(env1.getTemp()<env2.getTemp()){
			//小于所给温度返回1
			return 1;
		}else{
			//大于所给湿度返回-1
			if(env1.getHum()>env2.getHum()){
				return -1;
			//小于所给湿度返回1
			}else if(env1.getTemp()<env2.getHum()){
				return 1;
			}
		}
		return 0;
	}
}

最后进行测试~~代码如下:

 

 

import java.util.Arrays;
public class ComparatorTestMain {
	public static void main(String[] args) {
		EnvironmentForms env[] = {new EnvironmentForms(28.5f,50.1f),
				new EnvironmentForms(28.5f,60.1f),
				new EnvironmentForms(28.5f,40.1f),
				new EnvironmentForms(17.5f,50.1f),
				new EnvironmentForms(37.5f,50.1f)};
		System.out.println("********排序前********");
		System.out.println(Arrays.toString(env));
		System.out.println("********排序后********");
		Arrays.sort(env, new EnvironmentComparator());
		System.out.println(Arrays.toString(env));
	}
}

运行结果~~

 

 

********排序前********
[EnvironmentForm [温度=28.5, 湿度=50.1]
, EnvironmentForm [温度=28.5, 湿度=60.1]
, EnvironmentForm [温度=28.5, 湿度=40.1]
, EnvironmentForm [温度=17.5, 湿度=50.1]
, EnvironmentForm [温度=37.5, 湿度=50.1]
]
********排序后********
[EnvironmentForm [温度=37.5, 湿度=50.1]
, EnvironmentForm [温度=28.5, 湿度=60.1]
, EnvironmentForm [温度=28.5, 湿度=50.1]
, EnvironmentForm [温度=28.5, 湿度=40.1]
, EnvironmentForm [温度=17.5, 湿度=50.1]
]