Java gradle build 不重新编译源文件

Question

I have a gradle java project. I recently re-organized my source files into dub folder.

Originally all my source files were in the folder...

project_root/src/main/java

Now I have Class Foo.java in...

project_root/src/main/java/folderA

and I have Class Bar.java in...

project_root/src/main/java/folderB

Bar is dependant on Foo. When I change class Foo, class Bar does no recompile. Because Foo has changed, class Bar should have compilation errors, but they don't hit.

My build.gradle file is as follows...

apply plugin: 'java'

// Use maven repository
repositories {
    mavenCentral()
    google()
}

dependencies {
    implementation 'org.eclipse.jetty:jetty-servlet:9.4.19.v20190610'
    implementation 'org.eclipse.jetty:jetty-client:9.4.19.v20190610'
    implementation 'mysql:mysql-connector-java:8.0.16'
    implementation 'org.apache.commons:commons-dbcp2:2.7.0'
    implementation 'org.jdbi:jdbi3-core:3.10.1'
    implementation 'com.google.firebase:firebase-admin:6.11.0'
    compile 'com.google.apis:google-api-services-oauth2:v1-rev155-1.25.0'
    // implementation 'com.google.gms:google-services:4.3.3'

    // https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind
    compile group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.0.1'
    compile group: 'org.reflections', name: 'reflections', version: '0.9.11'

    compile project('chesslib')
    runtime files('../../chesslib/build/libs/chesslib-1.1.12.jar')
}

task runServer(type: JavaExec) {
   classpath = sourceSets.main.runtimeClasspath 
   main = 'ChessServer'
} 

task runClient(type: JavaExec) {
   classpath = sourceSets.main.runtimeClasspath 
   main = 'ChessClient'
   standardInput = System.in // without this, using Scanner on System.in won't work
}

task runCLITestApp(type: JavaExec) {
   classpath = sourceSets.main.runtimeClasspath 
   main = 'CLITestApp'
   standardInput = System.in
}

Answer 1

You are hitting a limitation of the incremental compilation in Gradle, as stated in the documentation :

If there is a mismatch in the package declaration and the directory structure of source files (eg package foo vs location bar/MyClass.java), then incremental compilation can produce broken output. Wrong classes might be recompiled and there might be leftover class files in the output.

So the recommendation is to go with the classical package to folder structure or disable incremental compilation:

compileJava {
  options.incremental = false
}

Answer 2

"When I change class Foo, class Bar does no recompile." It won't automatically recompile, you need to rebuild the project