What is T in java?

What is T in java?

T is a tag symbol in Java generics, representing Type (Java class).

Java generics (generics) are a new feature introduced in JDK 5. Generics provide a compile-time type safety detection mechanism, which allows programmers to detect illegal types at compile time.

The essence of generics is a parameterized type, which means that the data type being operated is specified as a parameter.

(Related video tutorial sharing: java video tutorial)

The meaning of tags in Java generics:

E - Element (used in collections, because elements are stored in collections)

T - Type (Java class)

K - Key (key)

V - Value (value)

N - Number (numeric type)

? - Represents uncertain java types

S, U, V - 2nd, 3rd, 4th types

Usage examples of generic T in Java:

public class MaximumTest
{
   // 比较三个值并返回最大值
   public static <T extends Comparable<T>> T maximum(T x, T y, T z)
   {                     
      T max = x; // 假设x是初始最大值
      if ( y.compareTo( max ) > 0 ){
         max = y; //y 更大
      }
      if ( z.compareTo( max ) > 0 ){
         max = z; // 现在 z 更大           
      }
      return max; // 返回最大对象
   }
   public static void main( String args[] )
   {
      System.out.printf( "%d, %d 和 %d 中最大的数为 %d\n\n",
                   3, 4, 5, maximum( 3, 4, 5 ) );
 
      System.out.printf( "%.1f, %.1f 和 %.1f 中最大的数为 %.1f\n\n",
                   6.6, 8.8, 7.7, maximum( 6.6, 8.8, 7.7 ) );
 
      System.out.printf( "%s, %s 和 %s 中最大的数为 %s\n","pear",
         "apple", "orange", maximum( "pear", "apple", "orange" ) );
   }
}

Running results:

3, 4 和 5 中最大的数为 5
6.6, 8.8 和 7.7 中最大的数为 8.8
pear, apple 和 orange 中最大的数为 pear

The above is the detailed content of What is T in java?. For more information, please follow other related articles on the PHP Chinese website!