list.get(0)防止NPE

时间:2024-01-08 16:44:38
package com.chuangjin.p2p;

import com.chuangjin.core.utils.JsonUtils;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

public class test {

    public static void main(String[] args) {
        List x = new ArrayList();
        x.add(null);
        x.add(new Student("brx"));
        x.add(null);
        System.out.println(x.size());
        System.out.println(JsonUtils.toJsonString(x));
        x.removeIf(Objects::isNull);
        System.));
        System.out.println(x.size());
        System.out.println(JsonUtils.toJsonString(x));
    }

    private static class Student{
        public Student(String name) {
            this.name = name;
        }

        private String name;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }
}

result:

3
[null,{"name":"brx"},null]
com.chuangjin.p2p.test$Student@649d209a
1
[{"name":"brx"}]