JDK8-四大核心函数式接口(三)

package cn.wcj.jdk8.lambda.test;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;

import org.junit.Test;
/*
* Java8 内置的四大核心函数式接口
*
* Consumer<T> : 消费型接口
*      void accept(T t);
*
* Supplier<T> : 供给型接口
*      T get();
*
* Function<T, R> : 函数型接口
*      R apply(T t);
*
* Predicate<T> : 断言型接口
*      boolean test(T t);
*
*/
public class LambdaTest3 {

//Consumer<T> : 消费型接口
@Test
public void test1() {
happy(50000.0, (money)->System.out.println("我们彤哥喜欢大保健，每次消费"+money+"元")) ;
}

public void happy(Double money,Consumer<Double> consumer){
consumer.accept(money);
}

//Supplier<T> : 供给型接口
@Test
public void test2(){
List<Integer> list = supply(10,()->(int)(Math.random()*100))  ;
list.forEach(System.out::println);
}

public List<Integer> supply(Integer num ,Supplier<Integer> supplier){
List<Integer> resultList=new ArrayList<Integer>()   ;
for(int x=0;x<num;x++)
resultList.add(supplier.get())   ;
return resultList ;
}

//Function<T, R> : 函数型接口
@Test
public void test3(){
String string = handleStr("\t\t\t\t 我大软院威武！！！   ",(str)->str.trim())    ;
System.out.println(string)   ;
String string2 = handleStr("我大软院威武", str->str.substring(2, 6));
System.out.println(string2);
}

public String handleStr(String target,Function<String, String> fun){
return fun.apply(target)   ;
}

//Predicate<T> : 断言型接口
@Test
public void test4(){
List<String>  list=Arrays.asList("atguigu","mldn","bjpowernode","itcast","sxt")   ;
List<String> newList = filterStr(list,string->string.length()>3) ;
newList.stream().forEach(System.out::println) ;
}

public List<String> filterStr(List<String> list,Predicate<String> predicate){
List<String>  resultList=new ArrayList<>()   ;
int size = list.size();
for(int x=0;x<size;x++){
String string = list.get(x) ;
if(predicate.test(string))
resultList.add(string)    ;
}
return resultList  ;
}

}