Question

我创建了两个自定义java DTO类

我尝试初始化它们但得到错误

...

PeriodicDataToServer pData = new PeriodicDataToServer(){

    location = new Location() {
        longtitude ="", latitude = "";
    };
}

...

public class PeriodicDataToServer {
    public Location location;
}


public class Location {

    public String longtitude;
    public String latitude;

}

...

错误：

Syntax error on token "location", VariableDeclaratorId expected after this token

Syntax error on token "longtitude", } expected

Answer 1

你可能意味着：

PeriodicDataToServer pData = new PeriodicDataToServer() {{

    location = new Location() {{
        longtitude ="", latitude = "";
    }};
}};

这也是我喜欢的技巧，但它有一个很大的缺点：它会创建匿名类。

对于其他读者：

class A { int n; }

 A a = new A() {{ n = 3; }};

有一个内部初始化块{ n = 3; }，如：

class B {
    int[] a = new int[2};
    {
        a[0] = 12;
        a[1] = 34;
    }
}

Answer 2

PeriodicDataToServer pData = new PeriodicDataToServer(){

    location = new Location() { // this is not possible.
        longtitude ="", latitude = "";
    };
}; // <- this semicolon was missing

您在这里使用匿名课程。你正在尝试用javascript表示法初始化字段！

但您可以使用初始化块（这是一种非常糟糕的样式）：

PeriodicDataToServer pData = new PeriodicDataToServer() {

    { // this is the init block for PeriodicDataToServer
        Location location = new Location() {
            { // this is the init block for Location
                longtitude ="", latitude = "";
            }
        };
    }
};

我的java立即初始化缺少什么？

2 个答案: