Java long compareTo（）及其示例-yiteyi-C++库

爪哇。朗，朗。compareTo（）是java中的一个内置方法，用于以数字方式比较两个长对象。如果此对象等于参数对象，则此方法返回0；如果此对象的数值小于参数对象，则此方法返回小于0；如果此对象的数值大于参数对象，则此方法返回大于0的值。

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语法：

public int compareTo(Object obj)

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

返回： 该函数返回三个值：

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

项目1： 下面的程序演示了函数的工作原理。

                     // 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

项目2： 下面的程序演示了在不传递任何参数的情况下函数的工作

                     // 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

方案3： 下面的程序演示了在参数中传递除object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

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