接口定义
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
public interface Print { void printUpperCase(String s); }
PrintString类
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
public class PrintString { public void printUpper(String s){ String result = s.toUpperCase(); System.out.println(result); } }
测试类
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
public class PrintDemo { public static void main(String[] args) { //使用Lambda表达式 usePrint(s -> System.out.println(s.toUpperCase())); //使用方法引用其他对象的实例方法 PrintString ps = new PrintString(); usePrint(ps::printUpper); } private static void usePrint(Print p){ p.printUpperCase("hello world"); } }
运行结果: