如何把List中的数据按某一字段排序

[sklyn1984]

ComparatorChain compChain = new ComparatorChain();
			compChain.addComparator(new BeanComparator("status"),
					true);

我这样写的，但是发现出来的结果并没有按该字段从大到小排序，status是百分比 如 22.18%，高手指教下

[空白-键]

java.util.Collections.sort(List<T> list) 

[sklyn1984]

	ComparatorChain compChain = new ComparatorChain();
			compChain.addComparator(new BeanComparator("status"),
					true);
			Collections.sort(list, compChain);

我这样写的，但是排序不对

[sklyn1984]

	ComparatorChain compChain = new ComparatorChain();
			compChain.addComparator(new BeanComparator("status"),
					true);
			Collections.sort(list, compChain);

我这样写的，但是排序不对

[良才2015]

Collections.sort(list, compChain);

这样是可以的。

[chabale]

你可以在数据库查询的时候排序，order by compChain

[孟祥月]

Collections.sort(List<T> list)

[sklyn1984]

要是我能SQL去ordery by我还跑程序里去写干嘛。 status是百分比的数字，这样写我测试出来确实不能正确的排序

[xierong2011]

import java.util.ArrayList;
import java.util.Collections;


public class StudentRanging {
    public static void main(String[] args) {
        ArrayList<Student> list=new ArrayList<Student>();
        Student a=new Student("胖胖",30,90.5);
        Student b=new Student("刘静",25,92.5);
        Student c=new Student("苏凯",21,80.5);
        Student d=new Student("许三多",28,90.5);
        Student e=new Student("成才",20,90.5);
        list.add(a);
        list.add(b);
        list.add(c);
        list.add(d);
        list.add(e);
        Collections.sort(list);
        for(Student s:list){
            System.out.println("info:"+s);
        }
    }

}

class Student implements Comparable{
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

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

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public double getScore() {
        return score;
    }

    public void setScore(double score) {
        this.score = score;
    }

    private String name;
    private int age;

    Student(String name, int age, double score) {
        this.name = name;
        this.age = age;
        this.score = score;
    }

    private double score;


    @Override
    /**
     * 实现按照成绩降序排序
     */
    public int compareTo(Object o) {
        Student s=(Student)o;
        int result=0;
        if(this.age>s.getAge())
           result=1;
        if(this.age<s.getAge())
           result=-1;
        return result; 
    }
}

给你一个例子 ，对你一定有用！

[xierong2011]

按学生的成绩排序

[dinglimin2009]

有特殊需求的话，可以实现comparable

[艳沐石]

public class ComparableTest {

	public static void main(String[] args) {
		Student[] ss = new Student[5];
		for (int i = 0; i < 5; i++) {
			int temp = (int) (Math.random() * 100);
			ss[i] = new Student(temp+"", temp, temp+"");
		}

		// 加一个比较器
		Arrays.sort(ss, new Comparator<Student>() {
			@Override
			public int compare(Student o1, Student o2) {
				return o1.getName().compareTo(o2.getName());
			}
		});
		for (Student s : ss) {
			System.out.println(s);
		}
	}
}

class Student {

	private String name;
	private int grade;
	private String cname;
	public Student(String name, int grade, String cname) {
		this.name = name;
		this.grade = grade;
		this.cname = cname;
	}
	/**
	 * @return Returns the name.
	 */
	public String getName() {
		return name;
	}
	/**
	 * @param name The name to set.
	 */
	public void setName(String name) {
		this.name = name;
	}
	/**
	 * @return Returns the grade.
	 */
	public int getGrade() {
		return grade;
	}
	/**
	 * @param grade The grade to set.
	 */
	public void setGrade(int grade) {
		this.grade = grade;
	}
	/**
	 * @return Returns the cname.
	 */
	public String getCname() {
		return cname;
	}
	/**
	 * @param cname The cname to set.
	 */
	public void setCname(String cname) {
		this.cname = cname;
	}
	public String toString() {
		StringBuffer sb = new StringBuffer();
		sb.append(name);
		sb.append(":");
		sb.append(grade);
		sb.append(",");
		sb.append(cname);
		return sb.toString();
	}
}

[zysnba]

类bean

package com;

import java.util.Comparator;

public class Student implements Comparator{

private String name;
private String age;
public Student(){}
public Student (String name,String age){
this.name=name;
this.age = age;

}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}

public int compare(Object arg0, Object arg1) {
Student user0 = (Student) arg0;
Student user1 = (Student) arg1;

// 首先比较年龄，如果年龄相同，则比较名字

int flag = user0.getAge().compareTo(user1.getAge());
if (flag == 0) {
return user0.getName().compareTo(user1.getName());
} else {
return flag;
}
}

}




test类
package com;

import java.util.Comparator;

public class Test implements Comparator {
public int compare(Object arg0, Object arg1) {
Student user0 = (Student) arg0;
Student user1 = (Student) arg1;

// 首先比较年龄，如果年龄相同，则比较名字

int flag = user0.getAge().compareTo(user1.getAge());
if (flag == 0) {
return user0.getName().compareTo(user1.getName());
} else {
return flag;
}
}

}
运行下看看效果

[zysnba]

package com;

import java.util.ArrayList;




public class T3 {
public static void main(String[] args) {
ArrayList<Student> list=new ArrayList<Student>();
Student a=new Student("e","20");
Student b=new Student("d","20");
Student c=new Student("c","20");
Student d=new Student("b","20");
Student e=new Student("a","20");
list.add(a);
list.add(b);
list.add(d);
list.add(e);
list.add(c);
Student Student = new Student();
Collections.sort(list,Student);

for(Student s:list){
System.out.println("结果 "+s.getName());
}
}




}


哈哈这个是测试类
哈哈

[yunyantian_89]

[Quote=引用 7 楼 sklyn1984 的回复:]

要是我能SQL去ordery by我还跑程序里去写干嘛。 status是百分比的数字，这样写我测试出来确实不能正确的排序
[/Quote]同感。