Arrays.sort用法

最新推荐文章于 2025-08-10 21:28:09 发布

iteye_2573

最新推荐文章于 2025-08-10 21:28:09 发布

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文章标签：算法

本文提供了一个Java程序示例，展示了如何对整数型数组、字符型数组和对象数组进行排序。通过对不同类型的数组使用Arrays.sort方法及自定义比较器，实现了有效排序。

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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) ;
}