Java 去除 ArrayList 集合中的重复元素
// One practice package Collection; import java.util.ArrayList; import java.util.Iterator; // 去除 ArrayList 集合中的重复元素 public class ArrayListTest { public static void sop(Object obj) { System.out.println(obj); } public static void main(String[] args) { ArrayList<String> arrayList = new ArrayList<String>(); arrayList.add("java01"); arrayList.add("java02"); arrayList.add("java03"); arrayList.add("java04"); arrayList.add("java01"); arrayList.add("java02"); arrayList.add("java03"); sop(arrayList); arrayList = singleElement(arrayList); sop(arrayList); } public static ArrayList<String> singleElement(ArrayList<String> al) { // 定义一个临时容器 ArrayList newAl = new ArrayList(); Iterator iterator = al.iterator(); while (iterator.hasNext()) { Object obj = iterator.next(); if (!newAl.contains(obj)) { newAl.add(obj); } } return newAl; } } // Practice Two package Collection; import java.util.ArrayList; import java.util.Iterator; // 将自定义对象作为元素存到 ArrayList 集合中,并去除重复元素 // 比如:存人对象。同姓名同年龄,视为同一个人。为重复元素 /* 1.对人描述,将数据封装进入对象 2.定义容器,将人存入 3.取出 List集合判断元素是否相同,依据是元素的 equals 方法。 */ class Person { private String name; private int age; Person(String name,int age) { this.name = name; this.age = age; } // 重写 equals 方法 public boolean equals(Object obj) { if (!(obj instanceof Person)) { return false; } Person person = (Person)obj; return this.name.equals(person.name) && this.age == person.age; } public String getname() { return name; } public int getage() { return age; } } public class ArrayListTest2 { public static void sop(Object obj) { System.out.println(obj); } public static void main(String[] args) { ArrayList al = new ArrayList(); al.add(new Person("Xp01", 30)); al.add(new Person("Xp02", 35)); al.add(new Person("Xp02", 35)); al.add(new Person("Xp03", 37)); al.add(new Person("Xp04", 35)); al.add(new Person("Xp04", 35)); al = singleElement(al); Iterator it = al.iterator(); while (it.hasNext()) { Person p = (Person)it.next(); sop(p.getname()+"::"+p.getage()); } } public static ArrayList singleElement(ArrayList<String> al) { // 定义一个临时容器 ArrayList newAl = new ArrayList(); Iterator iterator = al.iterator(); while (iterator.hasNext()) { Object obj = iterator.next(); if (!newAl.contains(obj)) { newAl.add(obj); } } return newAl; } }