Arrays.sort用法

最新推荐文章于 2024-07-22 08:37:45 发布

iteye_15971

最新推荐文章于 2024-07-22 08:37:45 发布

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分类专栏： java 文章标签： java 数据结构与算法

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package test;

import java.util.Arrays;
import java.util.Comparator;

public class ArraySortDemo {
/**
* 整数型数组排序
*/
public void sortIntArray() {
    int[] arrayToSort = new int[] { 48, 5, 89, 80, 81, 23, 45, 16, 2 };
   System.out.println("整数型数组排序,排序前:");
    for ( int i = 0; i < arrayToSort.length; i++){
    System.out.print(arrayToSort[i]+",");
   }
    // 调用数组的静态排序方法sort
  Arrays.sort(arrayToSort);
   System.out.println();
   System.out.println("排序后:");
    for ( int i = 0; i < arrayToSort.length; i++){
    System.out.print(arrayToSort[i]+",");
   }
}

/**
* 字符型数组排序demo
*/
public void sortStringArray() {
   String[] arrayToSort = new String[] { "Oscar", "Charlie", "Ryan",
     "Adam", "David","aff","Aff" };
   System.out.println();
   System.out.println("字符型数组排序,排序前:");
    for ( int i = 0; i < arrayToSort.length; i++){
    System.out.print(arrayToSort[i]+",");
   }
   System.out.println();
   System.out.println("排序后:");
    // 调用数组的静态排序方法sort
   Arrays.sort(arrayToSort);

    for ( int i = 0; i < arrayToSort.length; i++){
    System.out.print(arrayToSort[i]+",");
   }
}

/**
* 对象数组排序demo
*/
public void sortObjectArray() {
   Dog o1 = new Dog("dog1", 1);
   Dog o2 = new Dog("dog2", 4);
   Dog o3 = new Dog("dog3", 5);
   Dog o4 = new Dog("dog4", 2);
   Dog o5 = new Dog("dog5", 3);
   Dog[] dogs = new Dog[] { o1, o2, o3, o4, o5 };
   System.out.println();
   System.out.println("对象数组排序排序前:");
    for ( int i = 0; i < dogs.length; i++) {
    Dog dog = dogs[i];
    System.out.print(dog.getName()+"["+dog.getWeight()+"],");
   }
   Arrays.sort(dogs, new ByWeightComparator());
   System.out.println();
   System.out.println("排序后：");
    for ( int i = 0; i < dogs.length; i++) {
    Dog dog = dogs[i];
    System.out.print(dog.getName()+"["+dog.getWeight()+"],");
   }
}

public static void main(String[] args) {
   ArraySortDemo t = new ArraySortDemo();
   t.sortIntArray();
   t.sortStringArray();
   t.sortObjectArray();
}
}

/**
* 定义了一个Dog类
*/
class Dog {
private String name;
private int weight;

public Dog(String name, int weight) {
    this.setName(name);
    this.weight = weight;
}

public int getWeight() {
    return weight;
}

public void setWeight( int weight) {
    this.weight = weight;
}

public void setName(String name) {
    this.name = name;
}

public String getName() {
    return name;
}
}

/**
* 因为要对对象进行排序，所以要实现java.util.Comparator接口的compare(T o1, T o2)方法，在该方法中自定义排序算法。
*/
class ByWeightComparator implements Comparator {
public final int compare(Object pFirst, Object pSecond) {
    int aFirstWeight = ((Dog) pFirst).getWeight();
    int aSecondWeight = ((Dog) pSecond).getWeight();
    int diff = aFirstWeight - aSecondWeight;
    if (diff > 0)
     return 1;
    if (diff < 0)
     return -1;
    else
     return 0;
}
}

运行结果：

整数型数组排序,排序前:
48,5,89,80,81,23,45,16,2,
排序后:
2,5,16,23,45,48,80,81,89,
字符型数组排序,排序前:
Oscar,Charlie,Ryan,Adam,David,aff,Aff,
排序后:
Adam,Aff,Charlie,David,Oscar,Ryan,aff,
对象数组排序排序前:
dog1[1],dog2[4],dog3[5],dog4[2],dog5[3],
排序后：
dog1[1],dog4[2],dog5[3],dog2[4],dog3[5],

地方

List list = new ArrayList() ;
list.add("abcd") ;
list.add("abdc") ;
list.add("aadf") ;
list.add("aabf") ;
/* 将list转为数组 */
String[] strs = new String[list.size()] ;
list.toArray(strs) ;
/* 排序，只排2<=索引<4之间的数据 */
Arrays.sort(strs,2,4) ;
for(String str : strs){
System.out.println(str) ;
}