经典的排序map,要复习啊:
package com.citi;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class TestSortMap2 {
private final static Logger logger = LoggerFactory.getLogger(TestSortMap2.class);
public static void main(String... abc){
Map<Integer, String> map = new HashMap<Integer, String>();
map.put(1, "a");
map.put(2, "b");
map.put(3, "c");
for(Integer integer : map.keySet()){
logger.info("key= " + integer + " and value= " + map.get(integer));
}
Iterator<Map.Entry<Integer, String>> it = map.entrySet().iterator();
while(it.hasNext()){
Map.Entry<Integer, String> entry = it.next();
logger.info("key= " + entry.getKey() + " and value= " + entry.getValue());
}
for (Map.Entry<Integer, String> entry : map.entrySet()) {
logger.info("key= " + entry.getKey() + " and value= "
+ entry.getValue());
}
for(String string :map.values()){
logger.info("value is "+string);
}
}
}
第三种常用，第一种遍历其实遍历了两次map，Sonar检查会给critical issue.
TreeSet默认是升序排列,可以做降序排列:
package com.citi;
import java.util.Comparator;
import java.util.Set;
import java.util.TreeSet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class TestSortSet {
final static Logger logger = LoggerFactory.getLogger(TestSortSet.class);
public static void main(String... abc){
Set<Integer> set = new TreeSet<Integer>(new Comparator<Integer>(){
@Override
public int compare(Integer o1, Integer o2) {
return o2.compareTo(o1);
}
});
set.add(2);
set.add(1);
set.add(12);
set.add(4);
int count=0;
for(Integer in : set){
count++;
logger.info(count+" times "+"the value is {}",String.valueOf(in));
}
}
}
输出:
<span style="font-size:18px;">SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/C:/Documents%20and%20Settings/Administrator/%e6%a1%8c%e9%9d%a2/%e6%96%b0%e5%bb%ba%e6%96%87%e4%bb%b6%e5%a4%b9%20(4)/slf4j-1.7.7/slf4j-log4j12-1.7.7.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/C:/Documents%20and%20Settings/Administrator/%e6%a1%8c%e9%9d%a2/%e6%96%b0%e5%bb%ba%e6%96%87%e4%bb%b6%e5%a4%b9%20(4)/slf4j-1.7.7/slf4j-jdk14-1.7.7.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
1 times the value is 12
2 times the value is 4
3 times the value is 2
4 times the value is 1</span>
Student类:
package com.citi;
import java.util.Date;
public class Student {
private int id;
private String name;
private Date birthDay;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public Student(int id, String name, Date birthDay) {
super();
this.id = id;
this.name = name;
this.birthDay = birthDay;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Date getBirthDay() {
return birthDay;
}
public void setBirthDay(Date birthDay) {
this.birthDay = birthDay;
}
}
现在对一批学生进行排序:按id升序排列，id相同则按name排序，id和name都相同，则按birthDay排序:
第一种方式,做个匿名的Comparator内部类实现:
package com.citi;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class TestSortMap {
final static Logger logger = LoggerFactory.getLogger(TestSortMap.class);
public static void main(String... args) throws Exception{
final ThreadLocal<DateFormat> DF = new ThreadLocal<DateFormat>() {
protected DateFormat initialValue() {
return new SimpleDateFormat("yyyy-MM-dd");
}
};
Student s1 = new Student(2,"mucy",DF.get().parse("2014-10-01"));
Student s2 = new Student(2,"lucy",DF.get().parse("2014-10-03"));
Student s3 = new Student(10,"maomi",DF.get().parse("2014-10-05"));
Student s4 = new Student(34,"jack",DF.get().parse("2014-10-14"));
Student s5 = new Student(13,"tom",DF.get().parse("2014-10-04"));
Student s6 = new Student(2,"lucy",DF.get().parse("2014-10-02"));
Map<Integer,Student> stu = new HashMap<Integer,Student>();
stu.put(2, s1);
stu.put(1, s2);
stu.put(10, s3);
stu.put(4, s4);
stu.put(7, s5);
stu.put(8, s6);
List<Map.Entry<Integer,Student>> list = new ArrayList<Map.Entry<Integer,Student>>(stu.entrySet());
Collections.sort(list, new Comparator<Map.Entry<Integer,Student>>(){
@Override
public int compare(Entry<Integer, Student> o1,
Entry<Integer, Student> o2) {
if(o1.getValue().getId()-o2.getValue().getId()==0){
if(o1.getValue().getName().compareTo(o2.getValue().getName())==0){
return o1.getValue().getBirthDay().compareTo(o2.getValue().getBirthDay());
}
return o1.getValue().getName().compareTo(o2.getValue().getName());
}
return o1.getValue().getId()-o2.getValue().getId();
}
});
for(Map.Entry<Integer,Student> entry:list){
logger.info(entry.getValue().getId()+"-"+entry.getValue().getName()+"-"+DF.get().format(entry.getValue().getBirthDay()));
}
}
}
输出:
<span style="font-size:18px;">SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/C:/Documents%20and%20Settings/Administrator/%e6%a1%8c%e9%9d%a2/%e6%96%b0%e5%bb%ba%e6%96%87%e4%bb%b6%e5%a4%b9%20(4)/slf4j-1.7.7/slf4j-log4j12-1.7.7.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/C:/Documents%20and%20Settings/Administrator/%e6%a1%8c%e9%9d%a2/%e6%96%b0%e5%bb%ba%e6%96%87%e4%bb%b6%e5%a4%b9%20(4)/slf4j-1.7.7/slf4j-jdk14-1.7.7.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
2-lucy-2014-10-02
2-lucy-2014-10-03
2-mucy-2014-10-01
10-maomi-2014-10-05
13-tom-2014-10-04
34-jack-2014-10-14</span>
第二种方式，让Student实现Comparable接口,重写Student类，用TreeSet举例:
package com.citi;
import java.util.Date;
public class Student implements java.lang.Comparable<Student>{
private int id;
private String name;
private Date birthDay;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public Student(int id, String name, Date birthDay) {
this.id = id;
this.name = name;
this.birthDay = birthDay;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Date getBirthDay() {
return birthDay;
}
public void setBirthDay(Date birthDay) {
this.birthDay = birthDay;
}
@Override
public int compareTo(Student o) {
if(this.getId()-o.getId()==0){
if(this.getName().compareTo(o.getName())==0){
return this.getBirthDay().compareTo(o.getBirthDay());
}
return this.getName().compareTo(o.getName());
}
return this.getId()-o.getId();
}
}
测试类:
package com.citi;
import java.util.Set;
import java.util.TreeSet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class TestSortSet2{
final static Logger logger = LoggerFactory.getLogger(TestSortSet2.class);
public static void main(String... args) throws Exception{
Student s1 = new Student(2,"mucy",Constants.DF.get().parse("2014-10-01"));
Student s2 = new Student(2,"lucy",Constants.DF.get().parse("2014-10-03"));
Student s3 = new Student(10,"maomi",Constants.DF.get().parse("2014-10-05"));
Student s4 = new Student(34,"jack",Constants.DF.get().parse("2014-10-14"));
Student s5 = new Student(13,"tom",Constants.DF.get().parse("2014-10-04"));
Student s6 = new Student(2,"lucy",Constants.DF.get().parse("2014-10-02"));
Set<Student> set = new TreeSet<Student>();
set.add(s1);
set.add(s2);
set.add(s3);
set.add(s4);
set.add(s5);
set.add(s6);
for(Student student :set){
logger.info(student.getId()+"-"+student.getName()+"-"+Constants.DF.get().format(student.getBirthDay()));
}
}
}
输出:
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/C:/Documents%20and%20Settings/Administrator/%e6%a1%8c%e9%9d%a2/%e6%96%b0%e5%bb%ba%e6%96%87%e4%bb%b6%e5%a4%b9%20(4)/slf4j-1.7.7/slf4j-log4j12-1.7.7.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/C:/Documents%20and%20Settings/Administrator/%e6%a1%8c%e9%9d%a2/%e6%96%b0%e5%bb%ba%e6%96%87%e4%bb%b6%e5%a4%b9%20(4)/slf4j-1.7.7/slf4j-jdk14-1.7.7.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
2-lucy-2014-10-02
2-lucy-2014-10-03
2-mucy-2014-10-01
10-maomi-2014-10-05
13-tom-2014-10-04
34-jack-2014-10-14
Constants里只有一个DF属性:
package com.citi;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
public class Constants {
final static ThreadLocal<DateFormat> DF = new ThreadLocal<DateFormat>() {
protected DateFormat initialValue() {
return new SimpleDateFormat("yyyy-MM-dd");
}
};
}
我用HashMap测试Student实现Comparable接口做实验，做不通，有待研究.
实验的日志是搭配是:slf4j.api+slf4j-log4j适配+log4j实现.
因为加了一个slf4j-jdk的适配，因此出现multiple binding，不影响slf4j去绑定log4j.