Java包装类

 

 

public class Demo02 {

	public static void main(String[] args) {
		Integer integer1 = new Integer(20);
		Integer integer2 = new Integer(20);
		Integer integer3 = 20;
		Integer integer4 = 10;
		Integer integer5 = 30;
		Integer integer6 = 30;
		Integer integer7 = 200;
		Integer integer8 = 200;
		Integer integer9 = new Integer("20");
		
		//.equals()
		System.out.println("\".equals()\"的使用");
		System.out.println(integer1.equals(integer2));
		System.out.println(integer1.equals(integer3));
		System.out.println(integer5.equals(integer6));
		System.out.println(integer1.equals(integer9));
		System.out.println("===============================================");
		//.compareTo()
		System.out.println("\".compareTo\"的使用");
		System.out.println(integer1.compareTo(integer3));
		System.out.println(integer1.compareTo(20));
		System.out.println(integer1.compareTo(integer4));
		System.out.println(integer1.compareTo(10));
		System.out.println(integer1.compareTo(integer5));
		System.out.println(integer1.compareTo(30));
		System.out.println(integer1.compareTo(integer9));
		System.out.println("===============================================");
		//==
		System.out.println("\"==\"的使用");
		System.out.println(integer1 == integer2);
		System.out.println(integer1 == integer3);;
		System.out.println(integer5 == integer6);;
		System.out.println(integer7 == integer8);
		System.out.println("===============================================");
		//IntegerToString
		System.out.println("IntegerToString");
		System.out.println("\'.toString()\"方法");
		String str = Integer.toString(integer1);
		System.out.println(str);
		System.out.println("======================");
		System.out.println("包装类+\"+\"方法");
		String str1 = integer1 + "";
		System.out.println(str1);
		System.out.println("======================");
		System.out.println("基本类型+\"+\"方法");
		String str2 = integer1.intValue() + "";
		System.out.println(str2);
		System.out.println("======================");
		System.out.println("\'.toBinaryString()\"");
		String str3 = Integer.toBinaryString(integer1);
		System.out.println(str3);
		System.out.println("======================");
		System.out.println("\'.toHexString()\"");
		String str4 = Integer.toHexString(integer1);
		System.out.println(str4);
		System.out.println("===============================================");
		//StringToInteger
		System.out.println("StringToInteger");
		System.out.println("\'.parseInt()\"方法");
		int number = Integer.parseInt(str);
		System.out.println(number);
		System.out.println("============================");
		System.out.println("\"先转化成包装类，再转成int\"方法");
		System.out.println("转化成包装类");
		Integer integer10 = Integer.valueOf(str);
		System.out.println(integer10);
		System.out.println("(1)手动拆箱");
		int number2 = integer10.intValue();
		System.out.println(number2);
		System.out.println("======================");
		System.out.println("(2)自动拆箱");
		int number3 =integer1.intValue();
		System.out.println(number3);
		System.out.println("===============================================");

	}

}