method-reference - Read For Learn

The target type of this expression must be a functional interface in MethodReferences

Because that’s a method reference, the usage is a bit different: The argument that the consumer takes (s) will be still passed to the println method. here is Oracle’s tutorial on this.

Java Pass Method as Parameter

Edit: as of Java 8, lambda expressions are a nice solution as other answers have pointed out. The answer below was written for Java 7 and earlier… Take a look at the command pattern. Edit: as Pete Kirkham points out, there’s another way of doing this using a Visitor. The visitor approach is a little more involved – your nodes all need to be … Read more

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