Kotlin中常量和静态方法

常量

Java中:
   class StaticDemoActivity {
         public static final String LOAN_TYPE = "loanType";
         public static final String LOAN_TITLE = "loanTitle";
    }
Kotlin中:
  class StaticDemoActivity {
      companion object {
           val  LOAN_TYPE = "loanType"
           val  LOAN_TITLE = "loanTitle"
    }
}

或者

  class StaticDemoActivity {
      companion object StaticParams{
            val  LOAN_TYPE = "loanType"
            val  LOAN_TITLE = "loanTitle"
    }
}

 或者
  class StaticDemoActivity {
      companion object {
         const val LOAN_TYPE = "loanType"
         const val LOAN_TITLE = "loanTitle"
    }
}

注:const 关键字用来修饰常量,且只能修饰 val,不能修饰varcompanion object 的名字可以省略,可以使用 Companion来指代

引用常量(这里的引用只针对于java引用kotlin代码)

TestEntity类引用StaticDemoActivity中的常量

   class TestEntity {
        public TestEntity () {
            String title = StaticDemoActivity.Companion.getLOAN_TITLE();
    }
  }

  或者

  class TestEntity {
        public TestEntity () {
            String title = StaticDemoActivity.StaticParams.getLOAN_TITLE();
        }
  }

  或者

  class TestEntity {
        public TestEntity () {
            String title = StaticDemoActivity.LOAN_TITLE;
            String type= StaticDemoActivity.LOAN_TYPE;
        }
  }

静态方法

Java代码:
      class StaticDemoActivity {
          public static void test(){
                、、、
          } 
      }
Kotlin中:
      class StaticDemoActivity {
          companion object {
               fun test(){
                    、、、
                }
          }
      }

  或者

       class StaticDemoActivity {
          companion object StaticParams{
              fun test() {
                  、、、
              }
          }
      }
引用静态方法(这里的引用只针对于java引用kotlin代码)

TestEntity类引用StaticDemoActivity中的静态方法

    class TestEntity {
          public TestEntity () {
                StaticDemoActivity.Companion.test();
          }
    }

或者

    class TestEntity {
          public TestEntity () {
             StaticDemoActivity.StaticParams.test();
          }
    }

companion object {}中用来修饰 静态常量,或者静态方法单例等等