1、 基础

package collectiondemo;

import java.util.ArrayList;
import java.util.Collection;

/**
 * Created by apple on 20/5/3.
 */
public class Test1 {
    public static void main(String[] args) {
        Collection c = new ArrayList();
        //可以放不同类型的对象，但是不能是基础数据类型。因为基础在栈上，随时可能消失
        c.add("hello");
        c.add(new Name("ghj","jh"));
        c.add(new Integer(100));
        System.out.println(c.size());
        System.out.println(c);

        boolean h = c.remove("hello");
        boolean i = c.remove(new Integer(100));
        boolean g = c.remove(new Name("ghj","jh"));
        System.out.println(h + "  " + i + " " + g);

        System.out.println(c);
    }
}

class Name{
    private String firstName;
    private String lastName;

    public Name(String firstName,String lastName){
        this.firstName = firstName;
        this.lastName = lastName;

    }
    public String getLastName() {
        return lastName;
    }

    public String getFirstName() {
        return firstName;
    }


    public String toString(){
        return firstName + lastName;
    }
}

输出:
3
[hello, ghjjh, 100]
true true false
[ghjjh]

重写equals方法

package collectiondemo;

import java.util.ArrayList;
import java.util.Collection;

/**
 * Created by apple on 20/5/3.
 */
public class Test1 {
    public static void main(String[] args) {
        Collection c = new ArrayList();
        //可以放不同类型的对象，但是不能是基础数据类型。因为基础在栈上，随时可能消失
        c.add("hello");
        c.add(new Name("ghj","jh"));
        c.add(new Integer(100));
        System.out.println(c.size());
        System.out.println(c);

        boolean h = c.remove("hello");
        boolean i = c.remove(new Integer(100));
        boolean g = c.remove(new Name("ghj","jh"));
        System.out.println(h + "  " + i + " " + g);

        System.out.println(c);
    }
}

class Name{
    private String firstName;
    private String lastName;

    public Name(String firstName,String lastName){
        this.firstName = firstName;
        this.lastName = lastName;

    }
    public String getLastName() {
        return lastName;
    }

    public String getFirstName() {
        return firstName;
    }


    public String toString(){
        return firstName + lastName;
    }

    public boolean equals (Object obj){
        if (obj instanceof Name) {
            Name name = (Name)obj;
            return(firstName.equals(name.firstName)) &&
                    (lastName.equals(name.lastName));
        }
        return super.equals(obj);  //交给name的父类Object处理，object的equals方法实现方式：当前对象和传进来的
        //对象是不是一个对象，类似于==
    }
    public int hashCode(){
        return firstName.hashCode();
    }
}

输出
3
[hello, ghjjh, 100]
true true true
[]

Iterator接口

package collectiondemo;

import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;

/**
 * Created by apple on 20/5/3.
 */
public class TestIterator {
    public static void main(String[] args) {
        Collection c = new HashSet();
        c.add(new Name("f1","a1"));
        c.add(new Name("f20098","a245667"));
        c.add(new Name("f333","a5654"));

        Iterator i = c.iterator();
        while (i.hasNext()){
            //next()返回的是一个object,强制转换为相应类型
            Name n = (Name)i.next();
            System.out.println(n.getFirstName());
        }

        for (Iterator j = c.iterator(); j.hasNext(); ) {
            Name name = (Name)j.next();
            if (name.getFirstName().length() <3){
                j.remove();
                //如果换成c.remove(name) ,会产生例外
            }
        }

        System.out.println(c);


    }
}

输出：
f20098
f333
f1
[f20098 a245667, f333 a5654]

enhance的For循环

package collectiondemo;

import java.util.ArrayList;
import java.util.Collection;

/**
 * Created by apple on 20/5/3.
 */
public class EnhanceFor {
    public static void main(String[] args) {
        int arr[] = {1,3,4,6};
        for (int i:arr
             ) {
            System.out.println(i);
        }

        Collection c = new ArrayList();
        c.add(new String("ad"));
        c.add(new String("hg"));
        for (Object o:c
             ) {
            System.out.println(o);
        }
        //打印o出来，相当于调用了o的toString方法，而toString 方法重写了。
    }
}

输出：
1
3
4
6
ad
hg

Set

package collectiondemo;

import java.util.Collection;
import java.util.HashSet;
import java.util.Set;

/**
 * Created by apple on 20/5/3.
 */
public class SetDemo {
    public static void main(String[] args)
    {
        Set c1 = new HashSet();
        Set c2 = new HashSet();
        c1.add("a");
        c1.add("b");
        c1.add("c");
        c2.add("d");
        c2.add("a");
        c2.add("b");

        Set n = new HashSet(c1);
        n.retainAll(c2);  //交集
        Set su = new HashSet(c1);
        su.addAll(c2);
        System.out.println(n);
        System.out.println(su);

    }
}

输出：
[a, b]
[a, b, c, d]

List

package collectiondemo;

import java.util.LinkedList;
import java.util.List;

/**
 * Created by apple on 20/5/3.
 */
public class ListDemo {
    public static void main(String[] args) {
        List l = new LinkedList() ;
        for (int i = 0; i <  6; i++) {
            l.add("a" + i);
        }
        System.out.println(l);
        l.add(3,"a100");
        l.add(5,"a2");
        System.out.println(l);

        l.set(6,"a90");
        System.out.println(l);

        System.out.println((String)l.get(2) + " ");
        System.out.println(l.indexOf("a2"));
        System.out.println(l.lastIndexOf("a2"));

    }
}

输出：
[a0, a1, a2, a3, a4, a5]
[a0, a1, a2, a100, a3, a2, a4, a5]
[a0, a1, a2, a100, a3, a2, a90, a5]
a2
2
5

Collections

package collectiondemo;

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

/**
 * Created by apple on 20/5/3.
 */
public class CollectionsDemo {
    public static void main(String[] args) {
        List l1 = new LinkedList();
        List l2 = new LinkedList();
        for (int i = 0; i < 9 ; i++) {
            //System.out.println("a" + i);
            l1.add("a" + i);
        }
        System.out.println(l1);

        Collections.shuffle(l1);
        System.out.println(l1);

        Collections.reverse(l1);
        System.out.println(l1);

        Collections.sort(l1);
        System.out.println(l1);

        System.out.println(Collections.binarySearch(l1,"a5"));

    }
}

输出
[a0, a1, a2, a3, a4, a5, a6, a7, a8]
[a0, a7, a3, a4, a2, a5, a1, a8, a6]
[a6, a8, a1, a5, a2, a4, a3, a7, a0]
[a0, a1, a2, a3, a4, a5, a6, a7, a8]
5

Comparable

package collectiondemo;

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

/**
 * Created by apple on 20/5/3.
 */
public class ComparebleDemo {
    public static void main(String[] args) {
        List l1 = new LinkedList();
        l1.add(new Name("ma","li"));
        l1.add(new Name("ks","ai"));
        l1.add(new Name("oa","bi"));

        System.out.println(l1);
        Collections.sort(l1);
        System.out.println(l1);
    }
}


//Name继承Comparable，重写compareTo

    public int compareTo(Object o){
        Name n = (Name)o;  //强制转换成name
        int laC = lastName.compareTo(n.lastName); //lastname 是String类型，肯定实现了compareble接口
        return (
                laC != 0 ? laC:
                        firstName.compareTo(n.firstName)
                );
    }

泛型

package collectiondemo;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by apple on 20/5/3.
 */
public class BasicGeneric {
    public static void main(String[] args) {
        List<String> li = new ArrayList<String>();
        li.add("aa");
        li.add("bb");

        for (int i = 0; i <li.size() ; i++) {
            String s = li.get(i);
            System.out.println(s);

        }
        System.out.println("li:" + li);
    }
}

输出
aa
bb
li:[aa, bb]

泛型

package collectiondemo;

import com.sun.tools.internal.ws.wsdl.document.soap.SOAPUse;

import java.util.HashMap;
import java.util.Map;

/**
 * Created by apple on 20/5/3.
 */
public class MapDemo {
    public static void main(String[] args) {
/*        Map m1 = new HashMap();
        m1.put(1,"ab");
        m1.put(2,"cd");
        m1.put(3,"fg");
        System.out.println(m1.size());
        System.out.println(m1.containsKey(2));

        if (m1.containsKey(1)){
            int i = (Integer)m1.get(1);
            System.out.println(i);
        }

        Map m3 = new HashMap(m1);
        m3.putAll(m3);
        */
        Map<String,Integer> m1 = new HashMap<String,Integer>();
        m1.put("a1",5);
        m1.put("a2",2);

        System.out.println(m1.size());
        System.out.println(m1.containsKey("a1"));
        System.out.println(m1);
        if (m1.containsKey("a1")) {
            int i = m1.get("a1");
            System.out.println(i);
        }

    }
}

输出
2
true
{a1=5, a2=2}
5