1 public class PassTest {
2
3    float ptValue;
4    
5    // Methods t
6    o change the current values
7    public void changeInt (int value) {
8    value = 55;
9    }
10    
11    public void changeStr (String value) {
12    value = new String ( " different " );
13    }
14    
15    public void changeObjValue (PassTest ref) {
16    ref.ptValue = 99.0f;
17    }
18    
19    public static void main (String args[]) {
20    
21    String str;
22    int val;
23    
24    // Create an instance of the class
25    
26    PassTest pt = new PassTest ();
27    // Assign the int
28    val = 11;
29    
30    // Try to change it
31    pt.changeInt (val);
32    
33    // What is the current value?
34    System.out.println ( " Int value is: " + val);
35    
36    // Assign the string
37    str = new String ( " hello " );
38    
39    // Try to change it
40    pt.changeStr (str);
41    
42    // What is the current value?
43    System.out.println ( " Str value is: " + str);
44    
45    // Now set the ptValue
46    pt.ptValue = 101.0f;
47    
48    
49    // Now change the value of the float
50    // through the object reference
51    pt.changeObjValue (pt);
52    
53    // What is the current value?
54    System.out.println ( " Current ptValue is: " +
55      pt.ptValue);
56      }
57    }

System.out.println ( " Current ptValue is: " + pt.ptValue);这句输出为什么是99.0？