Collection(practice)

来源：互联网发布：高中化学大全软件下载编辑：程序博客网时间：2024/06/04 08:15
package collection;import java.util.ArrayList;class Person1{    private String name;    private int age;    public Person1(String name,int age){        this.age=age;        this.name=name;    }    public Person1(){}    public String getName(){        return name;    }    public void setName(String name){        this.name=name;    }    public int getAge(){        return age;    }    public void setAge(int age){        this.age=age;    }    @Override    public int hashCode() {        // TODO Auto-generated method stub        return this.age;    }    @Override    public boolean equals(Object obj) {        if(!(obj instanceof Person1)){            return false;        }        Person1 p=(Person1)obj;        return this.name.equals(p.name)&&this.age==p.age;    }    @Override    public String toString() {        return "Person@name:"+this.name+"age:"+this.age;    }}public class Demo1 {    public static void main(String[] args) {        ArrayList arr=new ArrayList();          Person1 p1=new Person1("jack",20);        Person1 p2=new Person1("rose",18);        Person1 p3=new Person1("rose",18);        arr.add(p1);        arr.add(p2);        arr.add(p3);        System.out.println(arr);        ArrayList arr2=new ArrayList();        for(int i=0;i<arr.size();i++){            Object obj=arr.get(i);            Person p=(Person)obj;            if(!(arr2.contains(p))){                arr2.add(p);            }        }        System.out.println(arr2);    }}package collection;import java.util.Iterator;import java.util.LinkedList;//逆序迭代public class Demo2 {    public static void main(String[] args) {        LinkedList list=new LinkedList();        list.add("aa");        list.add("bb");        list.add("cc");        Iterator dit=list.descendingIterator();        while(dit.hasNext()){            System.out.println(dit.next());        }    }}package collection;import java.util.Enumeration;import java.util.Vector;//vector:线程安全的ArrayListpublic class Demo3 {    public static void main(String[] args) {        Vector v=new Vector();        v.addElement("aaa");        v.addElement("bbb");        v.addElement("ccc");        System.out.println(v);        System.out.println(v.elementAt(2));        Enumeration ens=v.elements();        while(ens.hasMoreElements()){            System.out.println(ens.nextElement());        }    }}package collection;import java.util.ArrayList;import java.util.Collection;import java.util.Iterator;//使用迭代器清空public class Demo4 {    public static void main(String[] args) {        Collection coll=new ArrayList();        coll.add("aaa");        coll.add("bbb");        coll.add("ccc");        System.out.println(coll);        Iterator it=coll.iterator();        while(it.hasNext()){            it.next();            it.remove();        }        System.out.println(coll);    }}package collection;import java.util.ArrayList;import java.util.Iterator;import java.util.ListIterator;public class Demo5 {    public static void main(String[] args) {        ArrayList list=new ArrayList();        list.add("net");        list.add("os");        list.add("computer");        System.out.println(list);        ListIterator lit=list.listIterator();        while(lit.hasNext()){            String next=(String)lit.next();            System.out.println(next);        }        System.out.println("*********");        while(lit.hasPrevious()){            String next=(String) lit.previous();            System.out.println(next);        }    }}package collection;import java.util.ArrayList;import java.util.Iterator;import java.util.ListIterator;public class Demo6 {    public static void main(String[] args) {        ArrayList list=new ArrayList();        list.add("net");        list.add("os");        list.add("computer");        list.add("java");        System.out.println(list);        ListIterator lit=list.listIterator();        lit.next();        lit.next();        System.out.println(lit.next());        lit.add("C++");        System.out.println(list);    }}package collection;import java.util.TreeSet;//TreeSet继承Comparable实现compareto方法class Person implements Comparable{    private String name;    private int age;    private String gender;    public Person(String name,int age,String gender){        this.name=name;        this.age=age;        this.gender=gender;    }    public String getName(String name){        return name;    }    public void setName(String name){        this.name=name;    }    public int getAge(){        return age;    }    public void setAge(int age){        this.age=age;    }    public String getGender(){        return gender;    }    public void setGender(String gender){        this.gender=gender;    }    @Override    public int hashCode() {        return name.hashCode()+age*37;    }    @Override    public boolean equals(Object obj) {        if(!(obj instanceof Person)){            return false;        }        Person p=(Person)obj;        return this.name.equals(p.name)&&this.age==p.age;    }    @Override    public String toString() {        return "Person [name:"+name+",age="+age+",gender="+gender+"]";    }    @Override    public int compareTo(Object o) {        Person p=(Person)o;        System.out.println(this+" compareTo:"+p);        if(this.age>p.age){            return 1;        }        if(this.age<p.age){            return -1;        }        return this.name.compareTo(p.name);    }}public class Demo7 {    public static void main(String[] args) {        TreeSet ts=new TreeSet();        ts.add(new Person("aa",20,"男"));        ts.add(new Person("bb",18,"女"));        ts.add(new Person("cc",17,"男"));        ts.add(new Person("dd",30,"男"));        ts.add(new Person("dd",15,"女"));        System.out.println(ts);        System.out.println(ts.size());    }}package collection;import java.util.Comparator;import java.util.TreeSet;class Book{    private String name;    private double price;    public Book(){}    public String getName(){        return name;    }     public void setName(String name){        this.name=name;    }    public double getPrice(){        return price;    }    public void setPrice(double price){        this.price=price;    }    public Book(String name,double price){        this.name=name;        this.price=price;    }    @Override    public String toString() {        return "Book[name="+name+",price="+price+"]";    }}class MyComparator implements Comparator{    @Override    public int compare(Object o1, Object o2) {        Book b1=(Book)o1;        Book b2=(Book)o2;        System.out.println(b1+"comparator "+b2);        if(b1.getPrice()>b2.getPrice()){            return 1;        }        if(b1.getPrice()<b2.getPrice()){            return -1;        }        return b1.getName().compareTo(b2.getName());    }}public class Demo8 {    public static void main(String[] args) {        TreeSet ts=new TreeSet(new MyComparator());        ts.add(new Book("think in java",100));        ts.add(new Book("java核心",70));        ts.add(new Book("现代操作系统",50));        ts.add(new Book("java就业教程",35));        ts.add(new Book("abc in java",100));        System.out.println(ts);    }}package collection;import java.util.TreeSet;//切割字符串的空格public class Demo9 {    public static void main(String[] args) {        String str="8 10 15 5 2 7";        String[] strs=str.split(" ");        TreeSet ts=new TreeSet();        for(int x=0;x<strs.length;x++){            int y=Integer.parseInt(strs[x]);            ts.add(y);        }        System.out.println(ts);    }}package collection;import java.util.Collection;import java.util.HashMap;import java.util.Iterator;import java.util.Map;import java.util.Set;//获取map的键值public class Demo10 {    public static void main(String[] args) {        Map<Integer,String> map=new HashMap<Integer,String>();        map.put(1, "aaa");        map.put(2, "bbb");        map.put(3, "ccc");        System.out.println(map);        Set<Integer> ks=map.keySet();        Iterator<Integer> it=ks.iterator();        while(it.hasNext()){            Integer key=it.next();            String value=map.get(key);            System.out.println("key="+key+" value="+value);        }        //获取map的value元素        Collection<String> vs=map.values();        Iterator<String> ite=vs.iterator();        while(ite.hasNext()){            String value=ite.next();            System.out.println("value="+value);        }        //使用entry类存储映射关系        Set<Map.Entry<Integer, String>> es=map.entrySet();        Iterator<Map.Entry<Integer, String>> ites=es.iterator();        while(ites.hasNext()){            Map.Entry<Integer, String> en=ites.next();            Integer key=en.getKey();            String value=en.getValue();            System.out.println("key="+key+" value="+value);        }    }}package collection;//泛型public class Demo11<T> {    public static void main(String[] args) {        Demo11 d11=new Demo11<Integer>();        int d=(int) d11.getData(5);        System.out.println(d);    }    public T getData(T data){        return data;    }    public void reverse(T[] arr){        int start=0;        int end=arr.length-1;        for(int i=start,j=end;i<j;i++,j--){            T temp=arr[i];            arr[i]=arr[j];            arr[j]=temp;        }    }}package collection;public class Demo12 {    public static void main(String[] args) {        Father<String> f=new Father<String>("jack");        System.out.println(f.getT());        Father<Integer> f2=new Father<Integer>(20);        System.out.println(f2.getT());    }}class Father<T>{    private T t;    public Father(){}    public Father(T t){        super();        this.t=t;    }     public T getT(){        return t;    }    public void setT(T t){        this.t=t;    }}package collection;public class Demo13 {    public static void main(String[] args) {        MyInter<String> my=new MyInter<String>();        my.print("泛型");    }}interface Inter<T>{    void print(T t);}class MyInter<T> implements Inter<T>{    public void print(T t){        System.out.println("myprint:"+t);    }}
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