双重的将Java中的（）方法与示例进行比较-yiteyi-C++库

这个 JAVA朗，加倍。比较 是java中的一种内置方法，可以对两个双对象进行数值比较。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)

参数： 该方法接受一个参数。 obj –要与之比较的对象。

返回值： 该函数可以返回三个值：

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

下面的程序演示了java的工作原理。朗，加倍。compareTo（）方法：

项目1： 当两个对象不同时。

                     // Java program to demonstrate                   
                     // of java.lang.Double.compareTo() method                   
                     import                               java.lang.Math;                   
                             
                     class                               Gfg1 {                   
                             
                                         // Driver code                   
                                         public                               static                               void                               main(String args[])                   
                                         {                   
                             
                                         // When two objects are different                   
                                         Double obj1 =                               new                               Double(                               124                               );                   
                                         Double obj2 =                               new                               Double(                               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： 当没有通过辩论时。

                     // Java program to demonstrate                   
                     // of java.lang.Double.compareTo() method                   
                     import                               java.lang.Math;                   
                             
                     class                               Gfg1 {                   
                             
                                         // Driver code                   
                                         public                               static                               void                               main(String args[])                   
                                         {                   
                                         // When no argument is passed                   
                                         Double obj1 =                               new                               Double(                               124                               );                   
                                         Double obj2 =                               new                               Double(                               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 Double 
cannot be applied to given types;
        int compareValue = obj1.compareTo();
                               ^
  required: Double
  found: no arguments
  reason: actual and formal argument lists differ in length
1 error

方案3： 当对象以外的任何对象作为参数传递时。

                     // Java program to demonstrate                   
                     // of java.lang.Double.compareTo() method                   
                     import                               java.lang.Math;                   
                             
                     class                               Gfg1 {                   
                             
                                         // Driver code                   
                                         public                               static                               void                               main(String args[])                   
                                         {                   
                             
                                         // When anything other than object                   
                                         // argument is passed                   
                                         Double obj1 =                               new                               Double(                               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:15: error: incompatible types: String cannot be converted to Double
        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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