集合:
1.ArrayList集合类
import java.util.ArrayList;public class Demo01ArrayList {public static void main(String[] args) {ArrayList<Integer> arrayList = new ArrayList<>();arrayList.add(0,2);arrayList.add(1,3);arrayList.add(2,10);arrayList.add(1,30);System.out.println(arrayList);Integer integer =3;arrayList.remove(integer);System.out.println(arrayList);}
}
2. Vector
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.ListIterator;
import java.util.Vector;public class DemoVector {public static void main(String[] args) {Vector<String> vector = new Vector<>();vector.add("张三");vector.add("李四");vector.add("王五");Enumeration<String> elements = vector.elements();vector.addElement("赵六");while (elements.hasMoreElements()) {String name = elements.nextElement();if ("李四".equals(name)){vector.remove("李四");}System.out.println();}System.out.println(vector.firstElement());System.out.println(vector.lastElement());vector.insertElementAt("麻七",2);System.out.println(vector);ArrayList<String> list = new ArrayList<>();list.add("1");list.add("2");ListIterator<String> iterator = list.listIterator();list.add("3");list.add("4");while (iterator.hasNext()) {System.out.println(iterator.next());}}
}
3. LinkedList
import java.util.LinkedList;public class DemoLinkedList {public static void main(String[] args) {LinkedList<Object> linkedList = new LinkedList<>();linkedList.add("1");linkedList.addFirst("2");linkedList.addLast("3");System.out.println(linkedList); System.out.println(linkedList.getFirst());System.out.println(linkedList.getLast());System.out.println(linkedList.poll());System.out.println(linkedList.pollFirst());System.out.println(linkedList.pop());System.out.println(linkedList);linkedList.removeFirst();linkedList.removeLast();}
}
4.泛型
import java.util.ArrayList;public class DemoGenerics {public static void main(String[] args) {ArrayList arrayList = new ArrayList();arrayList.add(1);arrayList.add("字符串");for (Object o : arrayList) {System.out.println(o);}A<String> stringA = new A<>("张三");A<Name> nameA = new A<>(new Name("李", "亮"));nameA.name.printInfo();new B().fun("这是B类中的泛型方法");String string = new B().fun1("String");Integer integer = 1;
new B().<String>fun("integer");B b = new B();b.fun2(new Cat());}
}class A<T> {T name;public A(T t) {this.name = t;}
}class B {public <E> void fun(E e) {System.out.println(e);}public <F> F fun1(F f) {return f;}public <T extends Animal> void fun2(T t) {t.eat();t.run();}
}abstract class Animal {public abstract void run();public abstract void eat();
}class Cat extends Animal {@Overridepublic void run() {System.out.println("猫可以走猫步...");}@Overridepublic void eat() {System.out.println("🐱爱吃鱼...");}
}class JJLCat extends Cat{final String type = "金吉拉";String name;public JJLCat(String name) {this.name = name;}
}class Name {String xing;String ming;public Name(String xing, String ming) {this.xing = xing;this.ming = ming;}public void printInfo() {System.out.println("在下免贵姓" + xing + "名" + ming);}
}
5. ArrayList forEach() 方法
import java.util.ArrayList;
import java.util.function.Consumer;public class DemoFor {public static void main(String[] args) {ArrayList<Integer> integers = new ArrayList<>();integers.add(1);integers.add(2);integers.add(4);for (Integer integer : integers) {System.out.println(integer);}integers.iterator();integers.forEach(new Consumer<Integer>() {@Overridepublic void accept(Integer elem) {System.out.println("accept被执行了一次:" + elem * 3);}});}
}
6.可变长参数
import java.util.Arrays;
import java.util.List;public class MoreParameter {public static void main(String[] args) {
int[] ints = {3,4,5,6,7,8};System.out.println(ints);System.out.println(compute1(ints));System.out.println(compute2(3,4,5,6,7,8));List<String> stringList = Arrays.<String>asList("a", "b", "c");System.out.println(stringList);}public static int compute1(int[] allData){int res = 1;for (int data : allData) {res *= data;}return res;}public static int compute2(int... allData){System.out.println(allData); return 1;}}
7.Set
package com.shujia.day09_ArrayList_Set;import java.util.HashSet;
import java.util.Objects;
import java.util.Set;
import java.util.function.Consumer;public class Demo09Set {public static void main(String[] args) {Set<String> stringSet = new HashSet<String>();stringSet.add("2");stringSet.add("3");stringSet.add("2"); stringSet.add("4");System.out.println(stringSet);for (String value : stringSet) {System.out.println(value);}Set<Data> data = new HashSet<>();Data data1 = new Data("1");data.add(data1);data.add(new Data("2"));data.add(data1);data.add(new Data("1"));data.add(new Data("3")); System.out.println(data);System.out.println(data.size());for (Data datum : data) {System.out.println(datum.value);}}
}
class Data{String value;public Data(String value) {this.value = value;}@Overridepublic boolean equals(Object o) {if (this == o) return true;if (o == null || getClass() != o.getClass()) return false;Data data = (Data) o;return Objects.equals(value, data.value);}@Overridepublic int hashCode() {return Objects.hash(value);}
}
8. HashSet
import java.util.HashSet;public class DemoHashSet {public static void main(String[] args) {HashSet<Integer> integers = new HashSet<>();integers.add(2);integers.add(1);integers.add(5);integers.add(4);integers.add(6);System.out.println(integers); HashSet<String> strHash = new HashSet<>();strHash.add("11");strHash.add("10");strHash.add("8");strHash.add("0");strHash.add("a");System.out.println(strHash); Integer integer1 = 1;Integer integer2 = 2;System.out.println(integer1.hashCode()); System.out.println(integer2.hashCode()); }
}
9. LinkedHashSet
import java.util.LinkedHashSet;public class DemoLinkedHashSet {public static void main(String[] args) {LinkedHashSet<Integer> linkedHashSet = new LinkedHashSet<>();linkedHashSet.add(2);linkedHashSet.add(1);linkedHashSet.add(5);linkedHashSet.add(4);linkedHashSet.add(6);System.out.println(linkedHashSet); }
}