Java TimeUnit valueOf()方法及示例

TimeUnit类的valueOf()方法返回该类型的枚举常量，并指定名称。该字符串必须与用于声明该类型枚举常量的标识符完全匹配。(不允许有多余的空白字符)。

语法。

public static TimeUnit valueOf(String name)

参数。该方法接受一个强制性的参数名，它是要返回的枚举常量的名称。

返回值。该方法返回具有指定名称的枚举常量。

异常。该方法会产生以下异常。

下面的程序说明了TimeUnit valueOf()方法的实现。

程序 1:

// Java program to demonstrate// valueOf() method of TimeUnit Class  import java.util.concurrent.*;  class GFG {    public static void main(String args[])    {          // Create an object of TimeUnit class        // using valueOf() method        // Below statement is equivalent to        // TimeUnit Days = TimeUnit.DAYS;        TimeUnit Days = TimeUnit.valueOf("DAYS");          // Print the Enum of TimeUnit Object        System.out.println("TimeUnit object "                           + "is of type: "                           + Days);          // Convert current object to Hours        System.out.println("1 Day = "                           + Days.toHours(1)                           + " Hours");    }}

输出:

TimeUnit object is of type: DAYS1 Day = 24 Hours

程序2：演示NullPointerException

// Java program to demonstrate// valueOf() method of TimeUnit Class  import java.util.concurrent.*;  class GFG {    public static void main(String args[])    {          try {              System.out.println("Trying to create "                               + "TimeUnit object "                               + "using null Enum type");              // Create an object of TimeUnit class            // using valueOf() method            // by passing null as parameter            TimeUnit Days = TimeUnit.valueOf(null);        }          catch (NullPointerException e) {            System.out.println("\nException thrown: " + e);        }    }}

输出:

Trying to create TimeUnit object using null Enum typeException thrown: java.lang.NullPointerException: Name is null

程序3：演示IllegalArgumentException

// Java program to demonstrate// valueOf() method of TimeUnit Class  import java.util.concurrent.*;  class GFG {    public static void main(String args[])    {          try {              System.out.println("Trying to create "                               + "TimeUnit object "                               + "using ABCD Enum type");              // Create an object of TimeUnit class            // using valueOf() method            // by passing ABCD as parameter            TimeUnit Days = TimeUnit.valueOf("ABCD");        }          catch (IllegalArgumentException e) {            System.out.println("\nException thrown: " + e);        }    }}

输出:

Trying to create TimeUnit object using ABCD Enum typeException thrown: java.lang.IllegalArgumentException: No enum constant java.util.concurrent.TimeUnit.ABCD