JAVA 方法返回不同类型的参数

java 的方法返回不同类型的参数解决办法：

1. 返回类型为Object，接收返回参数后，强制转换成相应的类型。
2. 使用泛型标注返回类型。

示例：

/**
  * @ClassName: Test
 * @Description:
 * @Date: 7/11/2021 2:36 PM
 */
public class Test {


    public static void main(String[] args) {


        Integer demo1Value1 = (Integer) demo1(1);
        String demo1Value2 = (String) demo1(2);
        Boolean demo1Value3 = (Boolean) demo1(3);
        Double demo1Value4 = (Double) demo1(4);

        System.out.println(demo1Value1);
        System.out.println(demo1Value2);
        System.out.println(demo1Value3);
        System.out.println(demo1Value4);

        Integer demo2Value1 = demo2(1);
        String demo2Value2 = demo2(2);
        Boolean demo2Value3 = demo2(3);
        Double demo2Value4 = demo2(4);

        System.out.println(demo2Value1);
        System.out.println(demo2Value2);
        System.out.println(demo2Value3);
        System.out.println(demo2Value4);
    }

    public static  Object demo1(int type){
        switch (type){
            case 1:
                return new Integer(1);
            case 2:
                return new String("a");
            case 3:
                return new Boolean(false);
            default :
                return new Double(1.0);
        }
    }

    public static <T> T demo2(int type){
        switch (type){
            case 1:
                return (T) new Integer(1);
            case 2:
                return (T) new String("a");
            case 3:
                return (T) new Boolean(false);
            default:
                return (T) new Double(1.0);
        }
    }
 }