Java的如何比较2的ArrayList对象的不同 [英] Java how to compare 2 ArrayList of different objects

问题描述

我有一个问题想从2的ArrayList 对象 String中获得标签的araylist。我曾尝试以下，但看起来像我的理想输出是不是我期望的。

下面是code：

 公共类TestList {
    公共静态无效的主要（字串[] args）{
        标签标记1 =新标签（）;
        tag1.setId（15）;
        tag1.setTag（测试）;        标签标签2 =新标签（）;
        tag2.setId（15）;
        tag2.setTag（甲骨文）;        标签TAG3 =新标签（）;
        tag3.setId（16）;
        tag1.setTag（OHNO Cannoe素材）;        清单＆LT;标记和GT;标记列表=新的ArrayList＆LT;吊牌及GT;（）;        tagList.add（TAG1）;
        tagList.add（TAG2）;
        tagList.add（TAG3）;        的System.out.println（tagList.size（））;        AnotherTest TEST1 =新AnotherTest（）;
        test1.setId（15）;
        test1.setTestcol（另一个测试COL）;        AnotherTest测试2 =新AnotherTest（）;
        test2.setId（15）;
        test2.setTestcol（HAHAHA）;        清单＆LT; AnotherTest＆GT; anotherTests =新的ArrayList＆LT; AnotherTest＆GT;（）;
        anotherTests.add（TEST1）;
        anotherTests.add（测试2）;        的System.out.println（anotherTests.size（））;
        清单＆LT;串GT; getTaglist =新的ArrayList＆LT;串GT;（）;
        对于（AnotherTest anotherTest：anotherTests）{
            对于（标记标签：标记列表）{
                如果（tag.getId（）== anotherTest.getId（））{
                    // getTaglist =新的ArrayList＆LT;串GT;（）;
                    getTaglist.add（tag.getTag（））;
                }
            }
        }    对于（字符串str：getTaglist）{
        的System.out.println（STR）;
        //这得到：
       //大野Cannoe素材
       //甲骨文
       //大野Cannoe素材
       //甲骨文
    }}
}
 

为什么我没有得到测试＆放大器; 甲骨文作为我期望的结果（我用的ID == 15比较这两个列表）。我缺少什么？

解决方案

 标签TAG3 =新标签（）;
        tag3.setId（16）;
        tag1.setTag（大野Cannoe素材）; //这里是问题
 

使用

  tag3.setTag（大野Cannoe素材）;
 

你设置标记1 对象的属性再次大野Cannoe素材将在pviously写$ P $写入值测试

I have a problem trying to get an araylist of "tags" in String from 2 ArrayList of objects. I have tried the following but looks like my ideal output is not what I have expected.

Here is the code:

public class TestList {
    public static void main(String []args) {
        Tag tag1 = new Tag();
        tag1.setId(15);
        tag1.setTag("Test");

        Tag tag2 = new Tag();
        tag2.setId(15);
        tag2.setTag("Oracle");

        Tag tag3 = new Tag();
        tag3.setId(16);
        tag1.setTag("OHNO CANNOE");

        List<Tag> tagList = new ArrayList<Tag>();

        tagList.add(tag1);
        tagList.add(tag2);
        tagList.add(tag3);

        System.out.println(tagList.size());

        AnotherTest test1 = new AnotherTest();
        test1.setId(15);
        test1.setTestcol("Another test col");

        AnotherTest test2 = new AnotherTest();
        test2.setId(15);
        test2.setTestcol("HAHAHA");

        List<AnotherTest> anotherTests = new ArrayList<AnotherTest>();
        anotherTests.add(test1);
        anotherTests.add(test2);

        System.out.println(anotherTests.size());
        List<String> getTaglist = new ArrayList<String>();
        for(AnotherTest anotherTest : anotherTests) {
            for(Tag tag: tagList) {
                if(tag.getId()==anotherTest.getId()) {
                    //getTaglist = new ArrayList<String>();
                    getTaglist.add(tag.getTag());
                }
            }
        }

    for (String str: getTaglist) {
        System.out.println(str);
        //this gets:
       //OHNO CANNOE
       //Oracle
       //OHNO CANNOE
       //Oracle
    }

}
}

Why am I not getting "Test" & "Oracle" as my expected result (I am comparing with id ==15 for both lists). Am I missing anything?

解决方案

Tag tag3 = new Tag();
        tag3.setId(16);
        tag1.setTag("OHNO CANNOE");//here is the issue

use

tag3.setTag("OHNO CANNOE");

you are setting tag1 object's property again to "OHNO CANNOE" which will over write the previously written value "test"

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