Arraylist初始化总结

Arraylist初始化

Array.asList初始化

asList用法规范

ArrayList<Type> obj = new ArrayList<Type>(
        Arrays.asList(Object o1, Object o2, Object o3, ....so on));

asList实例

public class arraylist_stu {
    public static void main(String[] args) {
        ArrayList<String> a = new ArrayList<>(Arrays.asList("11", "2323"));
        System.out.print(a);
    }
}

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内部匿名类初始化

内部匿名类用法

ArrayList<T> obj = new ArrayList<T>(){{
		   add(Object o1);
		   add(Object o2);
		   add(Object o3);
                   ...
                   ...
		   }};

实例

public class arraylist_stu {
    public static void main(String[] args) {
        ArrayList<String> a = new ArrayList<>(){
            {
                add("1231");
                add("safaf");
            }
        };
        System.out.print(a);
    }
}

Collections.ncopies初始化

ncopies用法

ArrayList<T> obj = new ArrayList<T>(Collections.nCopies(count, element));

ncopies实例

public class arraylist_stu {
    public static void main(String[] args) {
        ArrayList<String> a = new ArrayList<>(
                Collections.nCopies(22,"王冲"));
        System.out.print(a);
    }
}

正常方法初始化

ArrayList<T> obj = new ArrayList<T>();
	   obj.add("Object o1");
	   obj.add("Object o2");
	   obj.add("Object o3");
                        ...
                        ...