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var,companion 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