學習筆記 | Java泛型

Java泛型

泛型函數實例

package example;

public class TDemo {

	public static void main(String[] args) {
		
		Integer[] a = {2,3,4};
		Double[] b = {2.0,3.0,4.0};
		Float[] c = {2.0f,3.0f,4.0f};
		
		printArr(a);
		printArr(b);
		printArr(c);
	}
		
	public static <T> void printArr(T[] a) {
		for(T item : a) {
			System.out.println(item);
		}
	}

}

輸出

2
3
4
2.0
3.0
4.0
2.0
3.0
4.0

代碼練習

package example;

public class MaxT {

		public static void main(String[] args) {
			System.out.println(max(2,3));
			System.out.println(max(23.0,3.1));
			System.out.println(max("a","b"));
		}
		
		public static <T extends Comparable<T>> T max(T t1, T t2) {
			T ret = t1;
			if(t1.compareTo(t2) == -1) {
				ret = t2;
			}
			return ret;
		}
	
}

輸出：

3
23.0
b