JAVA---Arrays工具类

java.util.Arrays:操作数组的工具类，里面定义了很多操作数组的方法

• 判断两个数组是否相等

  package lll;
  
  import java.util.Arrays;
  
  public class Test {
  	public static void main(String[] args) {
  		int[] arr1=new int[]{1,2,3,4};
  		int[] arr2=new int[]{1,2,3,4};
  		boolean isEquals = Arrays.equals(arr1, arr2);
  		System.out.println(isEquals);
  	}
  }
  
  

• 输出数组信息

  package lll;
  
  import java.util.Arrays;
  
  public class Test {
  	public static void main(String[] args) {
  		int[] arr1=new int[]{1,2,3,4};
  		int[] arr2=new int[]{1,2,3,4};
  		System.out.println(Arrays.toString(arr2));
  	}
  }
  
  

• 将指定值填充到数组当中

  package lll;
  
  import java.util.Arrays;
  
  public class Test {
  	public static void main(String[] args) {
  		int[] arr2=new int[]{1,2,3,4};
  		System.out.println(Arrays.toString(arr2));
  		//将数组中的所有元素都替换成99
  		Arrays.fill(arr2, 99);
  		System.out.println(Arrays.toString(arr2));
  }
  }
  
  

• 对数组进行排序

  package lll;
  
  import java.util.Arrays;
  
  public class Test {
  	public static void main(String[] args) {
  		int[] arr2=new int[]{3,2,1,4};
  		Arrays.sort(arr2);
  		System.out.println(Arrays.toString(arr2));
  }
  }
  
  

• 二分查找

  package lll;
  
  import java.util.Arrays;
  
  public class Test {
  	public static void main(String[] args) {
  		int[] arr2=new int[]{1,2,3,4,5,6,7,8,9};
  		int index = Arrays.binarySearch(arr2, 61);
  		//如果找到，返回索引值，如果找不到，返回一个负数
  		System.out.println(index);
  		System.out.println(Arrays.toString(arr2));
  }
  }