Java long compareTo() 与示例

Java.lang.Long.compareTo() 是Java中的一个内置方法，它以数字方式比较两个 Long 对象。如果此对象等于参数对象，则此方法返回 0；如果此对象在数值上小于参数对象，则返回小于 0；如果此对象在数值上大于参数对象，则返回大于 0 的值。

句法：

public int compareTo(Object obj)

Parameter: 
obj - The object which is to be compared to.

返回：函数返回三个值：

• 等于 0：对象等于参数对象
• 小于 0：对象小于参数对象
• 大于 0：对象大于参数对象

程序1：下面的程序演示了函数的工作。

// Java program to demonstrate
// of java.lang.Long.compareTo() method
import java.lang.Math;
  
class Gfg1 {
  
    // driver code
    public static void main(String args[])
    {
  
        // when two objects are different
        Long obj1 = new Long(124);
        Long obj2 = new Long(167);
        int compareValue = obj1.compareTo(obj2);
  
        if (compareValue == 0)
            System.out.println("object1 and object2 are equal");
        else if (compareValue < 0)
            System.out.println("object1 is less than object2");
        else
            System.out.println("object1 is greater than object2");
    }
}

输出：

object1 is less than object2

程序2：下面的程序演示了不传递参数时函数的工作

// Java program to demonstrate
// of java.lang.Long.compareTo() method
import java.lang.Math;
  
class Gfg1 {
  
    // driver code
    public static void main(String args[])
    {
        // when no argument is passed
        Long obj1 = new Long(124);
        Long obj2 = new Long(167);
  
        int compareValue = obj1.compareTo();
  
        if (compareValue == 0)
            System.out.println("object1 and object2 are equal");
        else if (compareValue < 0)
            System.out.println("object1 is less than object2");
        else
            System.out.println("object1 is greater than object2");
    }
}

输出：

prog.java:14: error: method compareTo in class Long cannot be applied to given types;
      int compareValue = obj1.compareTo(); 
                             ^
  required: Long
  found: no arguments
  reason: actual and formal argument lists differ in length
1 error

程序 3：下面的程序演示了在参数中传递除对象以外的任何内容时函数的工作

// Java program to demonstrate
// of java.lang.Long.compareTo() method
import java.lang.Math;
  
class Gfg1 {
  
    // driver code
    public static void main(String args[])
    {
  
        // when anything other than object
        // argument is passed
        Long obj1 = new Long(124);
  
        int compareValue = obj1.compareTo("gfg");
  
        if (compareValue == 0)
            System.out.println("object1 and object2 are equal");
        else if (compareValue < 0)
            System.out.println("object1 is less than object2");
        else
            System.out.println("object1 is greater than object2");
    }
}

输出：

prog.java:14: error: incompatible types: String cannot be converted to Long
      int compareValue = obj1.compareTo("gfg"); 
                                        ^
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
1 error