java 装箱与拆箱

public class BoxingDemo {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println("new Integer(2) ="
				+ "= 2 ? "+(new Integer(2)==2));
		
		System.out.println("new Integer(2) == new Integer(2) ? "
				+ ""+(new Integer(2)== new Integer(2)));
		
		System.out.println("Integer valueof(2) == Integer valueof(2) ? "
				+ ""+(Integer.valueOf(2) == Integer.valueOf(2)));
		
		System.out.println("Integer valueof(2000) == Integer valueof(2000) ? "
				+ ""+(Integer.valueOf(2000) == Integer.valueOf(2000)));
		
		System.out.println("Integer.valueof(2).intValue() == 2 ? "
				+ ""+(Integer.valueOf(2).intValue()==2));
		
		System.out.println("new Integer(2).equals(new Integer(2)) ? "
				+ "" +(new Integer(2).equals(new Integer(2))));
		
	}

}

这是运行结果

new Integer(2) == 2 ? true
new Integer(2) == new Integer(2) ? false
Integer valueof(2) == Integer valueof(2) ? true
Integer valueof(2000) == Integer valueof(2000) ? false
Integer.valueof(2).intValue() == 2 ? true
new Integer(2).equals(new Integer(2)) ? true