Java 如何将两个子字符串绑定到一个?
我有两根绳子Java 如何将两个子字符串绑定到一个?,java,data-binding,javafx,Java,Data Binding,Javafx,我有两根绳子 private StringProperties firstName; private StringProperties lastName; private StringProperties nickName; 名字和姓氏由用户选择,昵称是名字和姓氏前3个字符的串联 我怎么能做到 实际上我初始化它,就像这是整个类一样 public class Person { private StringProperty firstName; private StringProperty las
private StringProperties firstName;
private StringProperties lastName;
private StringProperties nickName;
名字和姓氏由用户选择,昵称是名字和姓氏前3个字符的串联
我怎么能做到
实际上我初始化它,就像这是整个类一样
public class Person {
private StringProperty firstName;
private StringProperty lastName;
private StringProperty nickName;
private ObservableList<Evento> eventi = FXCollections.observableArrayList();
public Person(String firstName, String lastName) {
this.firstName = new SimpleStringProperty(firstName);
this.lastName = new SimpleStringProperty(lastName);
if (firstName.length() > 2 && lastName.length() > 2)
this.nickName = new SimpleStringProperty(firstName.trim().substring(0,3).concat(lastName.trim().substring(0,3)));
else
this.nickName = new SimpleStringProperty("");
}
public ObservableList<Evento> getEventi() {
return eventi;
}
public String getFirstName() {
if(firstName == null) firstName = new SimpleStringProperty(this,"firstName");
return firstName.get();
}
public StringProperty firstNameProperty() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName.set(firstName);
}
public String getLastName() {
if(lastName == null) lastName = new SimpleStringProperty(this, "lastName");
return lastName.get();
}
public StringProperty lastNameProperty() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName.set(lastName);
}
public String getNickName() {
if(nickName == null) nickName = new SimpleStringProperty(this,"nickName");
return nickName.get();
}
public StringProperty nickNameProperty() {
return nickName;
}
@Override
public String toString() {
return getNickName() + "(" + getLastName() + " " + getFirstName() + ")";
}
}
但是当我允许用户更改名字或姓氏时,昵称将不会更新。您应该使用ReadOnlyStringProperty作为昵称:
private ReadOnlyStringWrapper nickName= new ReadOnlyStringWrapper();
...
public final String getNickName() {
return nickName.get();
}
public final ReadOnlyStringProperty nickNameProperty() {
return nickName.getReadOnlyProperty();
}
至于绑定,您可以使用Bindings类中的实用程序方法,或者为任何其他复杂情况实现您自己的绑定。此示例使用createStringBinding方法。它采用可调用函数接口(用于计算新值)和可观察属性列表(用于观察更改的值):
public Person(String firstName, String lastName) {
this.firstName = new SimpleStringProperty(firstName);
this.lastName = new SimpleStringProperty(lastName);
this.nickName.bind(Bindings.createStringBinding(()->{
if(this.firstName.get().length() > 2 && this.lastName.get().length() > 2) {
return this.firstName.get().substring(0,3).concat(this.lastName.get().trim().substring(0,3));
} else {
return "";
}
}, this.firstName, this.lastName));
}
您应该使用ReadOnlyStringProperty作为昵称:
private ReadOnlyStringWrapper nickName= new ReadOnlyStringWrapper();
...
public final String getNickName() {
return nickName.get();
}
public final ReadOnlyStringProperty nickNameProperty() {
return nickName.getReadOnlyProperty();
}
至于绑定,您可以使用Bindings类中的实用程序方法,或者为任何其他复杂情况实现您自己的绑定。此示例使用createStringBinding方法。它采用可调用函数接口(用于计算新值)和可观察属性列表(用于观察更改的值):
public Person(String firstName, String lastName) {
this.firstName = new SimpleStringProperty(firstName);
this.lastName = new SimpleStringProperty(lastName);
this.nickName.bind(Bindings.createStringBinding(()->{
if(this.firstName.get().length() > 2 && this.lastName.get().length() > 2) {
return this.firstName.get().substring(0,3).concat(this.lastName.get().trim().substring(0,3));
} else {
return "";
}
}, this.firstName, this.lastName));
}
您可以使用Bindings.format:
%3s中的3是字符串的最大长度
不过,这不会对字符串进行任何修剪,您可以在将字符串传递给firstName和lastName之前进行修剪
它也适用于小于3个字符的字符串。因此,如果名字是空字符串,您可以获得FoBar、FooB或Bar等昵称。您可以使用Bindings.format:
%3s中的3是字符串的最大长度
不过,这不会对字符串进行任何修剪,您可以在将字符串传递给firstName和lastName之前进行修剪
它也适用于小于3个字符的字符串。因此,如果名字是空字符串,你可以得到像FoBar、FooB或Bar这样的昵称。你有其他方法更新firstName和LastName吗?我有一个用于更新first和LastName的GUI,刚刚用整个Person类编辑了OP你有其他方法更新firstName和LastName吗?我有一个用于更新first和LastName的GUI,刚刚用整个Person类编辑了OP