public class User {
    private String name;

    public User(String name){
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;//以this来区*部变量和成员变量
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                '}';
    }
}

public class User {
    private String name;

    public User(String name){
        this.name = name;
    }

    public User(){
        this("ketang");
        System.out.println("this在构造方法中必须放在最前面");
        //放后面会报错:(编译器的规定)
        //Call to 'this()' must be first statement in constructor body
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                '}';
    }
}