java Integer.compare Integer.compareTo() 比较大小

今天看到这样的用法用于排序：

Integer.compare

Arrays.sort(intervals, (x, y) -> Integer.compare(x[0], y[0]));

java.lang包的Integer类的compare()方法比较作为参数给出的两个整数值(x，y)，如果(x == y)则返回零，如果(x <y)则返回小于零，如果(x> y)，则返回大于零的值。

public static void main(String args[]) 
    { 
        int a = 10; 
        int b = 20; 
  
        // as 10 less than 20, Output will be a value less than zero 
        System.out.println(Integer.compare(a, b)); 
  
        int x = 30; 
        int y = 30; 
  
        // as 30 equals 30, Output will be zero 
        System.out.println(Integer.compare(x, y)); 
  
        int w = 15; 
        int z = 8; 
  
        // as 15 is greater than 8, Output will be a value greater than zero 
        System.out.println(Integer.compare(w, z)); 
    } 

输出：-1 0 1

Integer.compareTo()

Java中Integer.compareto方法，用于在数值上比较两个Integer对象，2个必须都是Integer对象才能进行对比。

//Integer的compareTo方法,底层依据的是compare方法
public int compareTo(Integer anotherInteger) 
{
    //实际上Integer的比较是通过Integer中包括的整数来比较的
    return compare(this.value, anotherInteger.value);
}
public static int compare(int x, int y) 
{
    //如果a比b小,那么返回-1,相等就是0,否则就是1
    return (x < y) ? -1 : ((x == y) ? 0 : 1); 
} 

例子：

public class IntegerCompareToDemo {  
    public static void main(String args[]) {  
        Integer b = 5;
        Integer c = 15;
	System.out.println(b.compareTo(c)); //输出-1
	b = 15;
	System.out.println(b.compareTo(c)); //输出0
	b = 20;
	System.out.println(b.compareTo(c)); //输出1
    }  
}