Gradle使用异常集合

一、Could not find method leftShift() for arguments

1. 异常背景：在执行gradle脚本（build.gradle）命令gradle -q show时出错

2. 异常详情：

FAILURE: Build failed with an exception.

* Where:
Build file 'F:\test\build.gradle' line: 2

* What went wrong:
A problem occurred evaluating root project 'test'.
> Could not find method leftShift() for arguments [build_4812tmlsh4hbu49ky5fvjmj67$_run_closure1@260d7e26] on task ':show' of type org.gradle.api.DefaultTask.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 2s

3. 异常原因：操作符 << 在Gradle 4.x中被弃用（deprecated），并且在Gradle 5.0 被移除（removed）

4. 解决方法：(去掉<<)将脚本

apply plugin: 'java'
task show << {
    println relativePath(compileJava.destinationDir)
    println relativePath(processResources.destinationDir)
}  

修改为 

apply plugin: 'java'
task show {
    println relativePath(compileJava.destinationDir)
    println relativePath(processResources.destinationDir)
}

5. 查看效果：

二、Cannot add task 'wrapper' as a task with that name already exists.

1.异常背景：在执行gradle脚本（build.gradle）命令gradle wrapper时出错

2. 异常详情：

3. 异常原因：

4. 解决方法：

将build.gradle中内容

task wrapper(type: Wrapper) {
    gradleVersion = '6.2.2'
}

修改为

wrapper {
    gradleVersion = '6.2.2'
}