JAVA - 【Optional】辅助防止空指针异常

Optional是JDK1.8新增的类，在JDK1.8之前一般某个函数应该返回非空对象，但是偶尔会返回null，在JDK1.8中，不推荐直接返回该对象，返回之前需要进行处理；

☞ 关键：Optional.ofNullable(s).get()

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• 一般情况

☞ 由于对象元素没有初始化，运行会直接在s.getName处报空指针异常，但是究竟是哪一个deal造成的空指针异常？

 

public class Main{
	public static void main(String[] args) {
		
		Student s = new Student();
		s = deal1(s);
		s = deal2(s);
		s = deal2(s);
		String name = s.getName();
		System.out.println(name);
	}
	
	public static Student deal1(Student s){
		s = null;
		return s;
	}
	public static Student deal2(Student s){
		s = null;
		return s;
	}
	public static Student deal3(Student s){
		s = null;
		return s;
	}
}

• Optional优化

     

import java.util.Optional;

public class Main{
	public static void main(String[] args) {
		
		Student s = new Student();
		s = deal1(s);
		s = deal2(s);
		s = deal2(s);
		String name = s.getName();
		System.out.println(name);
	}
	public static Student deal1(Student s){
		s = null;
		return Optional.ofNullable(s).get();
	}
	public static Student deal2(Student s){
		s = null;
		return Optional.ofNullable(s).get();
	}
	public static Student deal3(Student s){
		s = null;
		return Optional.ofNullable(s).get();
	}
}