JAVA中判断数据不为空后执行数据操作、防止空指针报错的工具类，safes工具类-白红宇

JAVA中判断数据不为空后执行数据操作、防止空指针报错的工具类，safes工具类

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发布时间：2019-05-25

本文共 2439 字，大约阅读时间需要 8 分钟。

问题描述：

//问题描述， 由于集合为null        //会报Exception in thread "main" java.lang.NullPointerException        List
   
     userList = null;        userList.forEach(user->{            user.setUserName("李四");        });        System.out.println(userList);        //使用该工具类解决问题        List
    
      userList2 = null;        Safes.of(userList2).forEach(user->{            user.setUserName("李四");        });        System.out.println(userList2);

工具类代码：

package com.zcst.common.utils;import com.baomidou.mybatisplus.core.toolkit.CollectionUtils;import com.google.common.collect.Lists;import com.google.common.collect.Maps;import com.google.common.collect.Sets;import java.math.BigDecimal;import java.util.*;import java.util.function.Consumer;/** * @author Administrator */public class Safes {    public static 
   
     Map
    
      of(Map
     
       source) {        return (Map) Optional.ofNullable(source).orElse(Maps.newHashMapWithExpectedSize(0));    }    public static 
      
        Iterator
       
         of(Iterator
        
          source) { return (Iterator) Optional.ofNullable(source).orElse((Iterator
         
          ) Lists.newArrayListWithCapacity(0).iterator()); } public static 
          
            Collection
           
             of(Collection
            
              source) { return (Collection) Optional.ofNullable(source).orElse(Lists.newArrayListWithCapacity(0)); } public static 
             
               Iterable
              
                of(Iterable
               
                 source) { return (Iterable) Optional.ofNullable(source).orElse(Lists.newArrayListWithCapacity(0)); } public static 
                
                  List
                 
                   of(List
                  
                    source) { return (List) Optional.ofNullable(source).orElse(Lists.newArrayListWithCapacity(0)); } public static 
                   
                     Set
                    
                      of(Set
                     
                       source) { return (Set) Optional.ofNullable(source).orElse(Sets.newHashSetWithExpectedSize(0)); } public static BigDecimal of(BigDecimal source) { return (BigDecimal) Optional.ofNullable(source).orElse(BigDecimal.ZERO); } public static String of(String source) { return (String) Optional.ofNullable(source).orElse(""); } public static String of(String source, String defaultStr) { return (String) Optional.ofNullable(source).orElse(defaultStr); } public static 
                      
                        T first(Collection
                       
                         source) { if (CollectionUtils.isEmpty(source)) { return null; } T t = null; Iterator
                        
                          iterator = source.iterator(); if (iterator.hasNext()) { t = iterator.next(); } return t; } public static void run(Runnable runnable, Consumer
                         
                           error) { try { runnable.run(); } catch (Throwable t) { error.accept(t); } } static String trimToEmpty(String str) { return str == null ? "" : str.trim(); }}