Java ArrayList.remove（）

我想从对象中删除单词“ a”t1。为什么t2对象也受到影响？

package newproject;

import java.util.ArrayList; import java.util.Arrays;

public class NewProject {

public static void main(String[] args) {      
    String str[] = {"a", "b", "c"};
    ArrayList<String> words = new ArrayList<>();
    words.addAll(Arrays.asList(str));

    Test t1 = new Test(words);
    Test t2 = new Test(words);

    System.out.println("Result Before ");
    System.out.println("T1 " + t1.getWords());
    System.out.println("T2 " + t2.getWords());

    // Only T1 remove words, not T2
    t1.removeWords("a");

    System.out.println("Result After ");
    System.out.println("T1 " + t1.getWords());
    System.out.println("T2 " + t2.getWords());
}   

}

class Test { private ArrayList words;

Test(ArrayList<String> words){
    setWords(words);
}

void setWords(ArrayList words){ this.words = words; }

ArrayList <String> getWords() {
    return this.words;
}

void removeWords(String word) {
    this.words.remove(word);
}

}