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Stram流

简化集合，数组

package Stream;import java.util.ArrayList;public class StreamDemo1 {public static void main(String[] args) {ArrayList<String >list1 = new ArrayList<>();list1.add("abbbb");list1.add("abccc");list1.add("c");list1.add("d");list1.stream().filter(name->name.startsWith("a")).filter(name->name.length() == 5).forEach(name-> System.out.println(name));
//        ArrayList<String > list2 = new ArrayList<>();
//        for (String name : list1) {
//            if(name.startsWith("a")){
//                list2.add(name);
//            }
//        }
//        ArrayList<String > list3 = new ArrayList<>();
//        for (String name : list2) {
//            if(name.length() == 3){
//                list3.add(name);
//            }
//        }
//        for (String name : list3) {
//            System.out.println(name);
//        }}
}

单列集合

package Stream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.function.Consumer;
import java.util.stream.Stream;
public class StramDemo2 {public static void main(String[] args) {ArrayList<String >list = new ArrayList<>();Collections.addAll(list, "a","b","c","d","e");
//        Stream<String> stream1 = list.stream();
//        stream1.forEach(new Consumer<String>() {
//            @Override
//            public void accept(String s) {
//                System.out.println(s);
//            }
//        });list.stream().forEach(s-> System.out.println(s));}
}

双列集合获取

需要keyset

package Stream;
import java.util.HashMap;
public class StreamDemo3 {public static void main(String[] args) {HashMap<String ,Integer> hm = new HashMap<>();hm.put("a",111);hm.put("b",222);hm.put("c",333);hm.put("d",444);hm.keySet().stream().forEach(s -> System.out.println(s));}
}

数组获取

package Stream;import java.util.ArrayList;
import java.util.Arrays;public class StreamDemo4 {public static void main(String[] args) {int[] arr = {0,1,2,3,4,5,6,7,8,9};Arrays.stream(arr).forEach(s-> System.out.println(s));
//    Arrays.stream()}
}

零散数据

stream中间流

Stream结束

打印奇数

package Stream;import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;import static java.util.Locale.filter;public class StreamTest1 {public static void main(String[] args) {ArrayList<Integer> list = new ArrayList<>();Collections.addAll(list,1,2,3,4,5,6,7,8,9);List<Integer> newList = list.stream().filter(n ->n % 2 ==0).collect(Collectors.toList());System.out.println(newList);}
}

stream写Map