public class mytest {

    public static void main(String[] args) {

        ObjectSample o1 = new ObjectSample("hello");
        ObjectSample o2 = new ObjectSample("你好");

        System.out.println("before swap o1:" + o1.getTitle() + " o2:"
                + o2.getTitle());
        swapObject(o1, o2);
        System.out.println("after swap o1:" + o1.getTitle() + " o2:"
                + o2.getTitle());
    }

    static void swapObject(ObjectSample o1, ObjectSample o2) {
        String tmp = o1.getTitle();
        o1.setTitle(o2.getTitle());
        o2.setTitle(tmp);
    }
}

class ObjectSample {
    private String title;

    ObjectSample(String title) {
        this.title = title;
    }

    public String getTitle() {
        return title;
    }
    
    public void setTitle(String title){
        this.title = title;
    }
}

------解决方案--------------------
java中虽然可以叫“值传递” ，但是分开讲会更好些，对于基本数据类型我们叫“值传递”，对于对象叫“引用传递”更好。当然其实也都可以理解为“传值”。而你要交换的是属性的值，传递引用并不能改变其对象的属性和方法。当然那样是不行的。

------解决方案--------------------
java中对象是引用值的传递，你的
System.out.println("before swap o1:"+o1.getTitle()+" o2:"+o2.getTitle());  
swapObject(o1, o2);   //没有交换到
System.out.println("after swap o1:"+o1.getTitle()+" o2:"+o2.getTitle());  
}  
static void swapObject(ObjectSample o1, ObjectSample o2){ //相当与在方法体中交换了两个局部的对象，对你上面的o1,o2没影响 
ObjectSample temp = new ObjectSample("temp");  
temp = o1;  
o1 = o2;  
o2 = temp;  
}