java的instanceof使用-优快云博客

本文介绍了一种在Java中使用instanceof关键字判断对象类型的场景。通过创建CityInfo和ProvinceInfo两个类，根据输入的类型返回相应的对象。然后，利用instanceof判断返回的对象类型，并进行类型转换，打印出相应信息。

场景:使用instanceof判断类型
1.例子

public class TestInstanceof {
	
	public static Object getInfo(String type){
		CityInfo cityInfo =  new CityInfo();
		cityInfo.setCityName("厦门");
		cityInfo.setLandArea(1116.3);
		ProvinceInfo province = new ProvinceInfo();
		province.setProvinceName("福建");
		province.setLandArea(120000);
		if("福建".equals(type)){
			return province;
		}else{
			return cityInfo;
		}
	}
	
	private static final class  CityInfo{
		String cityName;
		double landArea;
		public String getCityName() {
			return cityName;
		}
		public void setCityName(String cityName) {
			this.cityName = cityName;
		}
		public double getLandArea() {
			return landArea;
		}
		public void setLandArea(double landArea) {
			this.landArea = landArea;
		}	
	}
	
	private static final class  ProvinceInfo{
		String provinceName;
		double landArea;
		public String getProvinceName() {
			return provinceName;
		}
		public void setProvinceName(String provinceName) {
			this.provinceName = provinceName;
		}
		public double getLandArea() {
			return landArea;
		}
		public void setLandArea(double landArea) {
			this.landArea = landArea;
		}	
	}
	
	public static void main(String []args){
		Object obj = getInfo("福建");
		if(obj instanceof CityInfo){
			CityInfo info = (CityInfo)obj;
			System.out.println("城市: " + info.getCityName() + "  面积:"+ info.getLandArea());
		}else{
			ProvinceInfo info = (ProvinceInfo)obj;
			System.out.println("省: " + info.getProvinceName() + "  面积:"+ info.getLandArea());
		}
	}
}

以上,TKS.