package com.bjsxt.others.guava;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import com.google.common.collect.ImmutableList;
/**
* 只读设置
* @author Administrator
*
*/
public class Demo01 {
/**
* @param args
*/
public static void main(String[] args) {
List<String> list =new ArrayList<String>();
list.add("a");
list.add("b");
list.add("c");
//对原有的list进行包装，相等于原有List的一个视图，快照，不够安全
List<String> readList =Collections.unmodifiableList(list);
//java.lang.UnsupportedOperationException
//readList.add("d");
list.add("d"); //改变原有List 视图也一起改变
//对比 查看 初始化List guava对只读设置 安全可靠，并且相对简单
List<String> immutableList =ImmutableList.of("a", "b", "c");
immutableList.add("d");//java.lang.UnsupportedOperationException
}
}
package com.bjsxt.others.guava;
import java.text.SimpleDateFormat;
import java.util.Collection;
import java.util.List;
import java.util.Set;
import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.base.Predicate;
import com.google.common.collect.Collections2;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
/**
* 函数式编程 :解耦
* 1、Predicate
* 2、Function
*
* 工具:Collections2.filter() 过滤器
* Collections2.transfer() 转换
* Functions.compose()组合式函数编程
* @author Administrator
*
*/
public class Demo02 {
/**
* @param args
*/
public static void main(String[] args) {
//组合式函数编程
//确保容器中的字符串长度不超过5，超过进行截取，后全部大写
List<String> list =Lists.newArrayList("bjsxt","good","happiness");
//确保容器中的字符串长度不超过5，超过进行截取
Function<String,String> f1 =new Function<String,String>(){
@Override
public String apply(String input) {
return input.length()>5?input.substring(0,5):input;
}
};
//转成大写
Function<String,String> f2 =new Function<String,String>(){
@Override
public String apply(String input) {
return input.toUpperCase();
}
};
//String =f2(f1(String))
Function<String,String> f =Functions.compose(f1, f2);
Collection<String> resultCol =Collections2.transform(list, f);
for(String temp:resultCol){
System.out.println(temp);
}
}
/**
* 转换
*/
public static void test2(){
//类型转换
Set<Long> timeSet =Sets.newHashSet();
timeSet.add(10000000L);
timeSet.add(99999999999999999L);
timeSet.add(2000000000L);
Collection<String> timeStrCol =Collections2.transform(timeSet, new Function<Long,String>(){
@Override
public String apply(Long input) {
return new SimpleDateFormat("yyyy-MM-dd").format(input);
}});
for(String temp:timeStrCol){
System.out.println(temp);
}
}
/**
* 过滤器
*/
public static void test1(){
//创建List 静态初始化
List<String> list =Lists.newArrayList("moom","son","dad","bjsxt","refer");
//找出回文 palindrome backwords mirror words
//匿名内部类对象: 匿名内部类，同时创建类对象
Collection<String> palindromeList =Collections2.filter(list, new Predicate<String>(){
@Override
public boolean apply(String input) {
//业务逻辑
return new StringBuilder(input).reverse().toString().equals(input);
}
});
for(String temp:palindromeList){
System.out.println(temp);
}
}
}
package com.bjsxt.others.guava;
import java.util.Set;
import com.google.common.base.Preconditions;
import com.google.common.collect.Constraint;
import com.google.common.collect.Constraints;
import com.google.common.collect.Sets;
/**
* 加入约束条件:非空、长度验证
* Constraint
* Preconditions
* Constraints
* @author Administrator
*
*/
public class Demo03 {
/**
* @param args
*/
public static void main(String[] args) {
Set<String> sets =Sets.newHashSet();
//创建约束
Constraint<String> constraint =new Constraint<String>(){
@Override
public String checkElement(String element) {
//非空验证
Preconditions.checkNotNull(element);
//长度验证 5-20为字符串
Preconditions.checkArgument(element.length()>=5 && element.length()<=20);
return element;
}
};
Set<String> cs =Constraints.constrainedSet(sets, constraint);
//cs.add(null); //java.lang.NullPointerException
// cs.add("good"); //java.lang.IllegalArgumentException
cs.add("bjsxt");
for(String str:cs){
System.out.println(str);
}
}
}
package com.bjsxt.others.guava;
import java.util.Set;
import com.google.common.collect.Sets;
import com.google.common.collect.Sets.SetView;
/**
* 集合的操作:交集、差集、并集
* Sets.intersection()
* Sets.difference()
* Sets.union();
* @author Administrator
*
*/
public class Demo04 {
/**
* @param args
*/
public static void main(String[] args) {
Set<Integer> sets =Sets.newHashSet(1,2,3,4,5,6);
Set<Integer> sets2 =Sets.newHashSet(3,4,5,6,7,8,9);
//交集
System.out.println("交集为:");
SetView<Integer> intersection =Sets.intersection(sets, sets2);
for(Integer temp:intersection){
System.out.println(temp);
}
//差集
System.out.println("差集为:");
SetView<Integer> diff =Sets.difference(sets, sets2);
for(Integer temp:diff){
System.out.println(temp);
}
//并集
System.out.println("并集为:");
SetView<Integer> union =Sets.union(sets, sets2);
for(Integer temp:union){
System.out.println(temp);
}
}
}
package com.bjsxt.others.guava;
import com.google.common.collect.BiMap;
import com.google.common.collect.HashBiMap;
/**
* HashMap 键唯一，值可以重复
* BiMap:双向Map(Bidirectional Map ) 键与值都不能重复(unique -valued map)
* @author Administrator
*
*/
public class Demo07 {
/**
* @param args
*/
public static void main(String[] args) {
BiMap<String,String> bimap=HashBiMap.create();
bimap.put("bjsxt", "[email protected]");
bimap.put("good","[email protected]");
//通过邮箱找用户
String user =bimap.inverse().get("[email protected]");
System.out.println(user);
System.out.println(bimap.inverse().inverse()==bimap);
}
}
package com.bjsxt.others.guava;
import java.util.Map;
import java.util.Set;
import com.google.common.collect.HashBasedTable;
import com.google.common.collect.Table;
import com.google.common.collect.Table.Cell;
import com.google.common.collect.Tables;
/**
* 双键的Map -->Table -->rowKey+columnKey+value
* 1、方法
* 所有的行数据:cellSet()
* 所有的学生: rowKeySet()
* 所有的课程:columnKeySet()
* 所有的成绩: values()
* 学生对应的课程: rowMap() +get(学生)
* row(学生)
* 课程对应的学生: columnMap +get(课程)
* column(课程)
* @author Administrator
*
*/
public class Demo08 {
/**
* @param args
*/
public static void main(String[] args) {
Table<String,String,Integer> tables=HashBasedTable.create();
//测试数据
tables.put("a", "javase", 80);
tables.put("b", "javase", 90);
tables.put("a", "oracle", 100);
tables.put("c", "oracle", 95);
//所有的行数据
Set<Cell<String,String,Integer>> cells =tables.cellSet();
for(Cell<String,String,Integer> temp:cells){
System.out.println(temp.getRowKey()+"-->"+temp.getColumnKey()+"-->"+temp.getValue());
}
System.out.println("==========学生查看成绩==============");
System.out.print("学生\t");
//所有的课程
Set<String> cours =tables.columnKeySet();
for(String t:cours){
System.out.print(t+"\t");
}
System.out.println();
//所有的学生
Set<String> stus =tables.rowKeySet();
for(String stu:stus){
System.out.print(stu+"\t");
Map<String,Integer> scores =tables.row(stu);
for(String c:cours){
System.out.print(scores.get(c)+"\t");
}
System.out.println();
}
System.out.println("==========课程查看成绩==============");
System.out.print("课程\t");
//所有的学生
Set<String> stuSet =tables.rowKeySet();
for(String t:stuSet){
System.out.print(t+"\t");
}
System.out.println();
//所有的课程
Set<String> courSet =tables.columnKeySet();
for(String c:courSet){
System.out.print(c+"\t");
Map<String,Integer> scores =tables.column(c);
for(String s:stuSet){
System.out.print(scores.get(s)+"\t");
}
System.out.println();
}
System.out.println("===========转换===========");
Table<String,String,Integer> tables2 =Tables.transpose(tables);
//所有的行数据
Set<Cell<String,String,Integer>> cells2 =tables2.cellSet();
for(Cell<String,String,Integer> temp:cells2){
System.out.println(temp.getRowKey()+"-->"+temp.getColumnKey()+"-->"+temp.getValue());
}
}
}
