Java
Java generics JDK 5 ,
Java
Java
- <E>
- intdoublechar
java
- E - Element ()
- T - TypeJava
- K - Key
- V - Value
- N - Number
- - java
public class GenericMethodTest
{
// printArray
public static < E > void printArray( E[] inputArray )
{
//
for ( E element : inputArray ){
System.out.printf( "%s ", element );
}
System.out.println();
}
public static void main( String args[] )
{
// Integer, Double Character
Integer[] intArray = { 1, 2, 3, 4, 5 };
Double[] doubleArray = { 1.1, 2.2, 3.3, 4.4 };
Character[] charArray = { 'H', 'E', 'L', 'L', 'O' };
System.out.println( ":" );
printArray( intArray ); //
System.out.println( "\n:" );
printArray( doubleArray ); //
System.out.println( "\n:" );
printArray( charArray ); //
}
}
: 1 2 3 4 5 : 1.1 2.2 3.3 4.4 : H E L L O
:
NumberNumber
extends
"extends""extends""implements"
public class MaximumTest
{
//
public static <T extends Comparable<T>> T maximum(T x, T y, T z)
{
T max = x; // x
if ( y.compareTo( max ) > 0 ){
max = y; //y
}
if ( z.compareTo( max ) > 0 ){
max = z; // z
}
return max; //
}
public static void main( String args[] )
{
System.out.printf( "%d, %d %d %d\n\n",
3, 4, 5, maximum( 3, 4, 5 ) );
System.out.printf( "%.1f, %.1f %.1f %.1f\n\n",
6.6, 8.8, 7.7, maximum( 6.6, 8.8, 7.7 ) );
System.out.printf( "%s, %s %s %s\n","pear",
"apple", "orange", maximum( "pear", "apple", "orange" ) );
}
}
3, 4 5 5 6.6, 8.8 7.7 8.8 pear, apple orange pear
:
public class Box<T> {
private T t;
public void add(T t) {
this.t = t;
}
public T get() {
return t;
}
public static void main(String[] args) {
Box<Integer> integerBox = new Box<Integer>();
Box<String> stringBox = new Box<String>();
integerBox.add(new Integer(10));
stringBox.add(new String(""));
System.out.printf(" :%d\n\n", integerBox.get());
System.out.printf(" :%s\n", stringBox.get());
}
}
:10 :
1 ? List<?> List<String>,List<Integer> List<>
import java.util.*;
public class GenericTest {
public static void main(String[] args) {
List<String> name = new ArrayList<String>();
List<Integer> age = new ArrayList<Integer>();
List<Number> number = new ArrayList<Number>();
name.add("icon");
age.add(18);
number.add(314);
getData(name);
getData(age);
getData(number);
}
public static void getData(List<?> data) {
System.out.println("data :" + data.get(0));
}
}
data :icon data :18 data :314
getData() List<?> nameagenumber
2List
| Web Proxy Viewer | New URL | Original Page |