ArrayList的addAll方法使用注意

<span style="font-size:18px;">package com.robot.test;

import java.util.ArrayList;

public class TestCode {
	public static void main(String[] args) {
		ArrayList<Student> stuList = new ArrayList<Student>();
		Student s1 = new Student(12, "jack");
		Student s2 = new Student(23, "Ann");
		Student s3 = new Student(76, "Mike");
		
		stuList.add(s1);
		stuList.add(s2);
		stuList.add(s3);
		
		ArrayList<Student> stuList2 = new ArrayList<Student>();
		stuList.addAll(stuList2); // 正确
		ArrayList<Student> stuList3 = null;
		stuList.addAll(stuList3); // 报错，由于stuList3为null指针
	}
}</span>

<span style="font-size:18px;">package com.robot.test;


public class Student{
<span style="white-space:pre">	</span>public int age;
<span style="white-space:pre">	</span>public String name;


<span style="white-space:pre">	</span>Student(int age, String name) {
<span style="white-space:pre">		</span>this.age = age;
<span style="white-space:pre">		</span>this.name = name;
<span style="white-space:pre">	</span>}
}</span>

总结：在使用ArrayList的addAll()方法的时候一定要进行非null的判断。