Java Double.compareTo()方法及示例

java.lang.Double.compareTo() 是java中的一个内置方法，可以对两个Double对象进行数字比较。如果该对象等于参数对象，该方法返回0；如果该对象在数字上小于参数对象，则返回小于0；如果该对象在数字上大于参数对象，则返回大于0的值。

语法

public int compareTo(Object obj)

参数： 该方法接受一个参数。

obj – 被比较的对象。

返回值： 该函数可以返回三个值。

下面的程序说明了java.lang.Double.compareTo()方法的工作。

程序1： 当两个对象都不同时。

// Java program to demonstrate// of java.lang.Double.compareTo() methodimport 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

程序2： 当没有传递参数时。

// Java program to demonstrate// of java.lang.Double.compareTo() methodimport 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 length1 error

程序3： 当对象以外的任何东西作为参数被传递时。

// Java program to demonstrate// of java.lang.Double.compareTo() methodimport 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 output1 error