How to use String parameters in Javas witch statements

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problem

When I try to use the String parameter in the switch statement (note that ctrType is a string)

Switch (ctrType) {case "01": exceptionType = "read FC parameter data"; break;case "03": exceptionType = "read current meter data saved by FC"; break;default:exceptionType = "unknown control code:" + ctrType;}

The following error is prompted:

Cannot switch on a value of type String for source level below 1.7. Only convertible int values or enum variables are permitted

It means that my jre version is too low to support. It is reported that before Java 7, switch could only support byte, short, char, int or their corresponding wrapper classes and Enum types. In Java 7, String support has finally been added.

Solve

General project

Install JDK 1.7 libraries, and change the configuration in the project to introduce the JDK version dependent library.

Maven project

Change the pom.xml file to set the target version of the maven-compiler-plugin plug-in to 1.7, for example

... org.apache.maven.pluginsmaven-compiler-plugin3.21.71.7...

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