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  • java 常用的类

    一、日期操作:Calendar类和SimpleDateFormat类

        public void Test1()
        {
            Calendar calendar=Calendar.getInstance();
            System.out.println(calendar.get(Calendar.DATE));
            System.out.println(calendar.get(Calendar.DAY_OF_MONTH));
            System.out.println(calendar.get(Calendar.DAY_OF_WEEK));
            System.out.println(calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH));
            System.out.println(calendar.get(Calendar.DAY_OF_YEAR));
        }

    二、Arrays类

        //数组排序
        public void Test2()
        {
            String[] strings= {"德布劳内","梅西","萨拉赫","卢卡库"};
            Arrays.sort(strings);
            System.out.println(Arrays.asList(strings));
        }
        
        //数组填充
        public void Test3()
        {
            int[] num=new int[4];
            String[] strings=new String[4];
            Arrays.fill(num, 4);
            System.out.println(Arrays.toString(num));
        }
        
        //数组比较
        public void Test4()
        {
            int[] num1=new int[5];
            int[] num2=new int[5];
            Arrays.fill(num1, 110);
            Arrays.fill(num2, 110);
            System.out.println(Arrays.equals(num1, num2));
        }

    三、Java 注释

    public class Annotation {
    
        //方法重写
        @Override
        public String toString()
        {
            return "rubbish";
        }
        
        //不建议使用
        @Deprecated
        public void TestMethod()
        {
            System.out.println("你是不是傻");
        }
        
        //屏蔽编译警告信息
        @SuppressWarnings(value="unchecked")
        public void Method2()
        {
            System.out.println("就此结束");
        }
        
        public void Test1()
        {
            String string="Color";
            string.toString();
            System.out.println(string);
        }
        
        public static void main(String[] args)
        {
            Annotation obj=new Annotation();
            obj.Method2();
        }
    }

    四、常用类

    1)Object类

    主要的方法:clone()、equals()、hashCode()、toString()

    2)获取键盘输入

        //Scanner获取键盘输入
        public void Test2()
        {
            Scanner sc = new Scanner(System.in);
            while (sc.hasNext()) 
            {
                String str = sc.next();
                System.out.println(str);
            }
        }
        
        //BufferedReader获取键盘输入
        public void Test3() throws IOException
        {
            BufferedReader bReader=new BufferedReader(new InputStreamReader(System.in));
            
            String string=null;
            string=bReader.readLine();
            System.out.println("you are value:"+string);
        }
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  • 原文地址:https://www.cnblogs.com/Optimism/p/10559806.html
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