import org.junit.Test;
import java.util.Arrays;
public class func {
//泛型方法：
//方法的返回值前面加上泛型 <T> ，返回值是一个数组 T[]
public static <T> T[] func(T[] array,int i,int j){
T temp = array[i];
array[i]=array[j];
array[j]=temp;
return array;
}
@Test
public void test(){
String[] arrays = {"vince","jack","tom","lily"};
String[] list = func(arrays, 0, 1);
System.out.println(Arrays.toString(list));
}
}
泛型的嵌套
//泛型的嵌套
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
public class MapTest {
public static void main(String[] args) {
Map<Integer, String> map = new HashMap<>();
map.put(1,"vince");
map.put(2,"jarry");
//此处用到泛型的嵌套：Set的泛型是Map.Entry，而Map.Entry的泛型又是<Integer, String>
Set<Map.Entry<Integer, String>> entries = map.entrySet();
for(Map.Entry entry:entries){
System.out.println(entry.getKey()+"-"+entry.getValue());
}
}
}
