java - 如何使用java比较两个arraylist元素

Question

我正在尝试创建一种方法来比较两个数组列表buttonresourceIds和buttonresourceIds2。我想对它们进行比较，看看它们是否共享按钮元素。然后返回它们共享的元素的“数量”。

ArrayList<String>> buttonresourceIds = new ArrayList<String>>();
ArrayList<String>> buttonresourceIds2 = new ArrayList<String>>();

for(int i=0;i<buttonresourceIds.size();i++){

    for(int j=0;j<buttonresourceIds2.size();j++){
        if(buttonresourceIds.contains(buttonresourceIds2.get(j))){
            System.out.println("Exist : "+buttonresourceIds2.get(j));
        }else{
            System.out.println("Not Exist : "+buttonresourceIds2.get(j));
        }
    }
}

它给了我结果，但循环不断重复。我错过了什么吗？

Answer 1

您不需要两个循环来执行此操作，一个循环就足以修复它

ArrayList<String>> buttonresourceIds = new ArrayList<String>>();
ArrayList<String>> buttonresourceIds2 = new ArrayList<String>>();
int common=0;
for(int j=0;j<buttonresourceIds2.size();j++){
    if(buttonresourceIds.contains(buttonresourceIds2.get(j))){
        System.out.println("Exist : "+buttonresourceIds2.get(j));
        common++;
    }else{
        System.out.println("Not Exist : "+buttonresourceIds2.get(j));
    }
}
return common;