Function calls in JAVA only have value transfer

Why does JAVA only have value transfer? The following code

public class TestSwap {
    
    
    public static void main(String... args){
    
    
        Student1 s1 = new Student1(20,"小周");
        Student1 s2 = new Student1(13,"瑞瑞");
        TestSwap swap = new TestSwap();
        swap.swap(s1,s2);
//        swap.swap1(s1,s2);
        System.out.println("s1:"+s1.getName());
        System.out.println("s2:"+s2.getName());
    }

    private void swap(Student1 x, Student1 y){
    
    
        Student1 temp = x;
        x = y;
        y = temp;
        System.out.println("x:"+x.getName());
        System.out.println("y:"+y.getName());
    }
    private void swap1(Student1 x, Student1 y){
    
    
        String temp = x.getName();
        x.name = y.getName();
        y.name = temp;
        System.out.println("x:"+x.getName());
        System.out.println("y:"+y.getName());
    }

    public static class Student1{
    
    
        int age;
        String name;

        public Student1(){
    
    

        }
        public Student1(int age, String name) {
    
    
            this.age = age;
            this.name = name;
        }

        public String getName() {
    
    
            return name;
        }
    }
}

The output result of calling swap	x: Ruirui, y: Xiaozhou, s1: Xiaozhou, s2: Ruirui
The output result of calling swap1	x: Ruirui, y: Xiaozhou, s1: Ruirui, s2: Xiaozhou

The above output description

• A method can change the state of an object parameter . (The swap1 method allows the name of the Student object to be exchanged)
• A method cannot let the object parameter refer to a new object . (The swap method cannot make an object reference point to another object)