JAVA容器小结
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JAVA容器小结

2019-06-14

JAVA容器小结

JAVA容器小结

副标题#e#

JAVA中的容器提供了很是完善的要领来生存工具，你可以利用这些东西来办理大数据量的问题。下面是笔者在开拓顶用到过的一些容器总结如此。

1 ArrayList

利用ArrayList很是简朴：建设一个实例，用add()插入工具，然后用get()会见这些工具，此时需要索引，就象数组一样，可是不需要方括号，ArrayList尚有size()要领，从而可以知道ArrayList的巨细，也可以制止因为越界而激发错误。别的，ArrayList长于随时机见元素，可是在List的中间插入和移处元素时较慢。下面是ArrayList的例子(来自thinking in java)：

/**//*
* @(#)AppleAndOrangesWithGenerics.java　　1.0 May 17, 2008
* @author:Administrator
* Copyright 2008 CSS WEB Microsystems, Inc. All rights reserved.
* CSS WEB ROOM PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package holding;
import java.util.ArrayList;
public class AppleAndOrangesWithGenerics ...{
public static void main(String[] args) ...{
ArrayList<Apple> apples = new ArrayList<Apple>();
for(int i = 0; i < 3; i++) ...{
apples.add(new Apple());
}
for(int i = 0; i < apples.size(); i++)
System.out.println(((Apple)apples.get(i)).id());
for(Apple c:apples)
System.out.println(c.id()+"-");
}
}
/**//*
* @(#)ListFeatures.java　　1.0 May 17, 2008
* @author:Administrator
* Copyright 2008 CSS WEB Microsystems, Inc. All rights reserved.
* CSS WEB ROOM PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package holding;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Random;
import typeinfo.pets.*;
public class ListFeatures ...{
public static void main(String[] args) ...{
Random rand = new Random(47);
List<Pet> pets = Pets.arrayList(7);
System.out.print("1: " + pets);
System.out.println();
Hamster h = new Hamster();
pets.add(h);
System.out.print("2: " + pets);
System.out.println();
System.out.print("3: " + pets.contains(h));
System.out.println();
pets.remove(h);
Pet p = pets.get(2);
System.out.print("4: " + pets.indexOf(p));
System.out.println();
Pet cymric = new Cymric();
System.out.print("5: " + pets.indexOf(cymric));
System.out.println();
System.out.print("6: " + pets.remove(cymric));
System.out.println();
System.out.print("7: " + pets.remove(p));
System.out.println();
System.out.print("8: " + pets);
System.out.println();
pets.add(3,new Mouse());
System.out.print("9: " + pets);
System.out.println();
List<Pet> sub = pets.subList(1,4);
System.out.print("sublist: " + sub);
System.out.println();
System.out.print("10: " + pets.containsAll(sub));
System.out.println();
Collections.sort(sub);
System.out.print("sorted sublist: " + sub);
System.out.println();
System.out.print("11: " + pets.containsAll(sub));
System.out.println();
Collections.shuffle(sub, rand);
System.out.print("shuffle sublist: " + sub);
System.out.println();
System.out.print("12: " + pets.containsAll(sub));
System.out.println();
List<Pet> copy = new ArrayList<Pet>(pets);
sub = Arrays.asList(pets.get(1),pets.get(4));
System.out.print("sub: " + sub);
System.out.println();
copy.retainAll(sub);
System.out.print("13: " + copy);
System.out.println();
copy = new ArrayList<Pet>(pets);
copy.remove(2);
System.out.print("14: " + copy);
System.out.println();
copy.removeAll(sub);
System.out.print("15: " + copy);
System.out.println();
copy.set(1, new Mouse());//Replace an element
System.out.print("16: " + copy);
System.out.println();
copy.addAll(2, sub);
System.out.print("17: " + copy);
System.out.println();
System.out.print("18: " + pets.isEmpty());
System.out.println();
pets.clear();
System.out.print("19: " + pets);
System.out.println();
System.out.print("20: " + pets.isEmpty());
System.out.println();
pets.addAll(Pets.arrayList(4));
System.out.print("21: " + pets);
System.out.println();
Object[] o = pets.toArray();
System.out.print("22: " + o[3]);
System.out.println();
Pet[] pa = pets.toArray(new Pet[0]);
System.out.print("23: " + pa[3].id());
System.out.println();
}
}


#p#副标题#e#

运行功效:

#p#分页标题#e#

1: [Rat, Manx, Cymric, Mutt, Pug, Cymric, Pug]
2: [Rat, Manx, Cymric, Mutt, Pug, Cymric, Pug, Hamster]
3: true
4: 2
5: -1
6: false
7: true
8: [Rat, Manx, Mutt, Pug, Cymric, Pug]
9: [Rat, Manx, Mutt, Mouse, Pug, Cymric, Pug]
sublist: [Manx, Mutt, Mouse]
10: true
sorted sublist: [Manx, Mouse, Mutt]
11: true
shuffle sublist: [Mouse, Manx, Mutt]
12: true
sub: [Mouse, Pug]
13: [Mouse, Pug]
14: [Rat, Mouse, Mutt, Pug, Cymric, Pug]
15: [Rat, Mutt, Cymric, Pug]
16: [Rat, Mouse, Cymric, Pug]
17: [Rat, Mouse, Mouse, Pug, Cymric, Pug]
18: false
19: []
20: true
21: [Manx, Cymric, Rat, EgyptianMau]
22: EgyptianMau
23: 14

2　LinkedList

LinkedList也像ArrayList一样实现了根基的List接口,可是它执行某些操纵(好比插入、删除)时要比ArrayList越发的高效，可是在随时机见操纵方面要逊色一些。另外，LinkedList还添加了可以使其用作栈、行列或双端行列的要领。下面是关于LinkedList利用的例子：

/**//*
* @(#)LinkedListFeatures.java　　1.0 May 18, 2008
* @author:Administrator
* Copyright 2008 CSS WEB Microsystems, Inc. All rights reserved.
* CSS WEB ROOM PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package holding;
import java.util.LinkedList;
import static net.mindview.util.Print.*;
import typeinfo.pets.Hamster;
import typeinfo.pets.Pet;
import typeinfo.pets.Pets;
import typeinfo.pets.Rat;
public class LinkedListFeatures ...{
public static void main(String[] args) ...{
LinkedList<Pet> pets = new LinkedList<Pet>(Pets.arrayList(5));
print(pets);
print("pets.getFirst(): " + pets.getFirst());
print("pets.element(): " + pets.element());
print("pets.peek(): " + pets.peek());
print("pets.remove(): " + pets.remove());
print("pets.removeFirst(): " + pets.removeFirst());
print("pets.poll(): " + pets.poll());
print(pets);
pets.addFirst(new Rat());
print("After addFirst(): " + pets);
pets.offer(Pets.randomPet());
print("After offer(): " + pets);
pets.add(Pets.randomPet());
print("After add(): " + pets);
pets.addLast(new Hamster());
print("After addLast(): " + pets);
print("pets.removeLast(): " + pets.removeLast());
}
}

运行功效：

[Rat, Manx, Cymric, Mutt, Pug]
pets.getFirst(): Rat
pets.element(): Rat
pets.peek(): Rat
pets.remove(): Rat
pets.removeFirst(): Manx
pets.poll(): Cymric
[Mutt, Pug]
After addFirst(): [Rat, Mutt, Pug]
After offer(): [Rat, Mutt, Pug, Cymric]
After add(): [Rat, Mutt, Pug, Cymric, Pug]
After addLast(): [Rat, Mutt, Pug, Cymric, Pug, Hamster]
pets.removeLast(): Hamster

#p#副标题#e#

List的排序和查询：List排序和查询所利用的要领与工具数组所利用的相应要领有沟通的名字和语法，只是用Collections的static要领取代Arrays的要领罢了。例子如下：

/**//*
* @(#)ListSortSearch.java　　1.0 May 18, 2008
* @author:Administrator
* Copyright 2008 CSS WEB Microsystems, Inc. All rights reserved.
* CSS WEB ROOM PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package containers;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.ListIterator;
import java.util.Random;
import containers.Utilities;
import static net.mindview.util.Print.*;
public class ListSortSearch ...{
public static void main(String[] args) ...{
List<String> list = new ArrayList<String>(Utilities.list);
list.addAll(Utilities.list);
print(list);
Collections.shuffle(list,new Random(47));
print("shuffled: " + list);
ListIterator<String> it = list.listIterator(10);
while(it.hasNext()) ...{
it.next();
it.remove();
}
print("Trimmed: " + list);
Collections.sort(list);
print("sorted: " + list);
String key = list.get(7);
int index = Collections.binarySearch(list, key);
print("Location of " + key + " is " + index +
", list.get(" + index + ") = " + list.get(index));
Collections.sort(list,String.CASE_INSENSITIVE_ORDER);
print("Case-insensitive sorted: " + list);
key = list.get(7);
index = Collections.binarySearch(list, key, String.CASE_INSENSITIVE_ORDER);
print("Location of " + key + " is " + index +
", list.get(" + index + ") = " + list.get(index));
}
}

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