Question

我正在关注使用列表和地图作为构造函数的this博文。

为什么以下列表无法强制反对？

class Test {
    static class TestObject {
        private int a = 1;
        protected int b = 2;
        public int c = 3;
        int d = 4;
        String s = "s";
    }

    static main(args) {
        def obj = [1, 2, 3, 4, 's'] as TestObject
    }
}

我得到了这个例外：

Caught: org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object '[1, 2, 3, 4, s]' with class 'java.util.ArrayList' to class 'in.ksharma.Test$TestObject' due to: groovy.lang.GroovyRuntimeException: Could not find matching constructor for: in.ksharma.Test$TestObject(java.lang.Integer, java.lang.Integer, java.lang.Integer, java.lang.Integer, java.lang.String)
org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object '[1, 2, 3, 4, s]' with class 'java.util.ArrayList' to class 'in.ksharma.Test$TestObject' due to: groovy.lang.GroovyRuntimeException: Could not find matching constructor for: in.ksharma.Test$TestObject(java.lang.Integer, java.lang.Integer, java.lang.Integer, java.lang.Integer, java.lang.String)
    at in.ksharma.Test.main(Test.groovy:22)

Answer 1

您可以使用地图：

class Test {
    static class TestObject {
        private int a = 1;
        protected int b = 2;
        public int c = 3;
        int d = 4;
        String s = "s";
    }

    static main(args) {
        def o = ['a':1,b:'2',c:'3','d':5,s:'s'] as TestObject
        println o.d
    }
}

马上考虑一下清单。

修改

嗯..我不确定列表是否可行。仅当您添加适当的构造函数时。完整样本：

class Test { static class TestObject { TestObject() { } TestObject(a,b,c,d,s) { this.a = a this.b = b this.c = c this.d = d this.s = s } private int a = 1; protected int b = 2; public int c = 3; int d = 4; String s = "s"; } static main(args) { def obj = ['a':1,b:'2',c:'3','d':5,s:'s'] as TestObject assert obj.d == 5 obj = [1, 2, 3, 6, 's'] as TestObject assert obj.d == 6 } }

Answer 2

如果您计划使用地图，那么也可以实现以下内容（不使用as）：

class TestObject {
  private int a = 1
  protected int b = 2
  public int c = 3
  int d = 4
  String s = "s"
}

TestObject obj = [a: 1, b: 2, c: 3, d: 6, s: 's']

assert obj.a == 1 && obj.b == 2 && obj.c == 3 && obj.d == 6 && obj.s == 's'

如何将Groovy列表强制转换为对象？

2 个答案: