Arrays.sort用法
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) ;
}
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