方法傳遞的參數賦值問題--堆棧的存儲問題

	
	public static Object change(Object obj) {
		System.out.println(" in change method, the obj hash code is:" + obj.hashCode());
		if (obj instanceof Map) {
			((Map) obj).put("key", "1");
			//System.out.println(" in change method, after set value the 'Map' hash code is:" + obj.hashCode());
		} else if (obj instanceof Number) {
			obj = 2;
			//System.out.println(" in change method, after set value the 'Number' hash code is:" + obj.hashCode());
		} else if (obj instanceof String) {
			obj = 3;
			//System.out.println(" in change method, after set value the 'String' hash code is:" + obj.hashCode());
		}
		return obj;
	}
	
	public static Long change(Long b,Long a) {
		b = 1L;
		a = b;
		System.out.println("內部測試結果："+a);
		return b;
	}
	
	public static int change(int a) {
		a = 1;
		System.out.println("內部測試結果："+a);
		return a;
	}
	public static void main(String[] args) {
		Map map = new HashMap();
		System.out.println("out change method, the old 'map' hash code is:" + map.hashCode());
		map.put("key", "0");
		change(map);
		System.out.println(map.get("key"));
		
		Long l = new Long(0);
		System.out.println("out change method, the old 'l' hash code is:" + l.hashCode());
		change(l);
		System.out.println(l);
		
		String s = new String("0");
		System.out.println("out change method, the old 's' hash code is:" + s.hashCode());
		change(s);
		System.out.println(s);
		
		String as = new String("abc");
		String bs = "abc";
		String cs = "abc";
		String ds = new String("abc");
		
		System.out.println(as==bs);
		
		System.out.println(bs==cs);
		
		System.out.println(cs==ds);
		
		System.out.println(ds==as);
		
		Long la = 0L;
		Long la1 = 2L;
		change(la1,la);
		System.out.println("Long la1:"+la);
		
		Long la2 = new Long(2);
		Long change2 = change(la2,la);
		System.out.println("Long la2:"+la);
		
		int ia = 0;
		change(ia);
		System.out.println("int ia:"+ia);
	}

輸出結果

out change method, the old 'map' hash code is:0
 in change method, the obj hash code is:106095
1
out change method, the old 'l' hash code is:0
 in change method, the obj hash code is:0
0
out change method, the old 's' hash code is:48
 in change method, the obj hash code is:48
0
false
true
false
false
內部測試結果：1
Long la1:0
內部測試結果：1
Long la2:0
內部測試結果：1
int ia:0

解答方案：堆棧的存儲問題