通过反射获取对象的field进行判空-优快云博客

本文介绍了一个使用Java反射机制检查Car类实例字段是否为空的示例。通过反射获取Car实例的字段，并判断其值是否为null，展示了如何在运行时动态地访问和修改对象的属性。

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实体Bean Car

package com.mytest.testcase1;

public class Car {
	
	//品牌
	private String mBrand;
	//类型
	private String mSort;
	//排量
	private int outPutVol;
	
	public String getmBrand() {
		return mBrand;
	}
	public void setmBrand(String mBrand) {
		this.mBrand = mBrand;
	}
	public String getmSort() {
		return mSort;
	}
	public void setmSort(String mSort) {
		this.mSort = mSort;
	}
	public int getOutPutVol() {
		return outPutVol;
	}
	public void setOutPutVol(int outPutVol) {
		this.outPutVol = outPutVol;
	}

}

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通过反射获取实例对象的field进行判空

package com.mytest.testcase1;

import java.lang.reflect.Field;


public class TestCar {
	
	public static void main(String[] args) throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException, ClassNotFoundException {
		
		Car carInstance = new Car();
		carInstance.setmBrand("Audi");
		carInstance.setmSort(null);
		carInstance.setOutPutVol(2);
		
		Class<?> clzz = carInstance.getClass();
		
		Field[] fields = clzz.getDeclaredFields();
		for(Field field : fields ) {
			Field f = clzz.getDeclaredField(field.getName());
			f.setAccessible(true);
			Object obj = (Object)f.get(carInstance);
			if(null == obj) {
				System.out.println(field.getName() + " is null");
			} else {
				
				System.out.println(field.getName() + " is " + obj);
			}
		}
		
		
	}
	
}

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输出：

mBrand is Audi

mSort is null

outPutVol is 2