Gradle - application

Run No arg main class

Java 

package examples;

public class TestMain {

    public static void main(String[] params) {

        System.out.println("hello");

    }

}

build.gradle

apply plugin: 'java'

apply plugin: 'application'

mainClassName= 'examples.TestMain'

repositories {

    mavenCentral()

}

dependencies {

    testCompile 'junit:junit:4.12'

}

Run

$ gradle run

> Task :run

hello

Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.

Use '--warning-mode all' to show the individual deprecation warnings.

See https://docs.gradle.org/6.3/userguide/command_line_interface.html#sec:command_line_warnings

BUILD SUCCESSFUL in 952ms

3 actionable tasks: 3 executed

Run main class with hard code arg

Java

package examples;

public class TestMain {

    public static void main(String[] params) {

        System.out.println("hello " + params[0]);

    }

}

build.gradle

apply plugin: 'java'

apply plugin: 'application'

mainClassName= ‘examples.TestMain'

repositories {

    mavenCentral()

}

dependencies {

    testCompile 'junit:junit:4.12'

}

run.args = ['abc']

Run

apply plugin: 'java'

apply plugin: 'application'

mainClassName= 'examples.TestMain'

repositories {

    mavenCentral()

}

dependencies {

    testCompile 'junit:junit:4.12'

}

run.args = ['abc']

Run main class with command line arg

Java

package examples;

public class TestMain {

    public static void main(String[] params) {

        System.out.println("hello " + params[0]);

    }

}

build.gradle

apply plugin: 'java'

apply plugin: 'application'

mainClassName= 'examples.TestMain'

repositories {

    mavenCentral()

}

dependencies {

    testCompile 'junit:junit:4.12'

}

run.args = [project.args] //simply args can work as well

Run

$ gradle clean run -Pargs=ABC

> Task :run

hello ABC

Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.

Use '--warning-mode all' to show the individual deprecation warnings.

See https://docs.gradle.org/6.3/userguide/command_line_interface.html#sec:command_line_warnings

BUILD SUCCESSFUL in 760ms

4 actionable tasks: 4 executed

Gradle java project - code and test

source code

Hello.java

package examples;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

public class Hello {

    public String hello() throws IOException {

        InputStream in = Thread.currentThread().getContextClassLoader().getResourceAsStream("hello.txt");

        BufferedReader reader = new BufferedReader(new InputStreamReader(in));

        StringBuilder s = new StringBuilder();

        String line;

        while ((line = reader.readLine()) != null) {

            System.out.println(line);

            s.append(line);

        }

        return s.toString();

    }

    

}

prepare build.gradle and apply java plugin

apply plugin: ‘java'

compile java

$ gradle compileJava

BUILD SUCCESSFUL in 620ms

1 actionable task: 1 executed

Clean classes

$ gradle clean

BUILD SUCCESSFUL in 564ms

1 actionable task: 1 executed

Build code and run test

Add junit dependency

apply plugin: 'java'

repositories {

    mavenCentral()

}

dependencies {

    testCompile 'junit:junit:4.12'

}

Add test code

package examples;

import java.io.IOException;

import java.net.URISyntaxException;

import java.nio.file.Files;

import java.nio.file.Paths;

import org.junit.Assert;

import org.junit.Test;

public class HelloTest {

    @Test

    public void hello() throws IOException, URISyntaxException {

        Hello h = new Hello();

        String hello = h.hello();

        String hellotest = new String(Files.readAllBytes(Paths.get(Thread.currentThread().getContextClassLoader().getResource("hellotest.txt").toURI())));

        Assert.assertEquals(hellotest, hello);

    }

   

}

Compile and Test

$ gradle build

Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.

Use '--warning-mode all' to show the individual deprecation warnings.

See https://docs.gradle.org/6.3/userguide/command_line_interface.html#sec:command_line_warnings

BUILD SUCCESSFUL in 1s

6 actionable tasks: 6 executed

Test Report

Open in browser: build/reports/tests/test/index.html 

Gradle helloworld task

Edit build.gradle

task helloworld {

    println "Hello world"

}

List tasks and find helloworld

$gradle tasks --all

...

Other tasks

-----------

helloworld

prepareKotlinBuildScriptModel

BUILD SUCCESSFUL in 1s

1 actionable task: 1 executed

Run task

$ gradle helloworld

> Configure project :

Hello world

BUILD SUCCESSFUL in 931ms

Gradle Helloworld - Main Class

Reference

https://openhome.cc/Gossip/Spring/Gradle.html

Thanks 良葛格, his explanation is so simple and good to read and practice!!

Class

package examples;

public class HelloMain {

    public static void main(String[] params) {

        System.out.println("Hello world:" + params[0]);

    }

}

build.gradle

apply plugin:'java'

apply plugin:'application'

mainClassName='examples.HelloMain'

run {

    args username

}

run

$ gradle run -Pusername=Isaac

> Task :run

Hello world:Isaac

BUILD SUCCESSFUL in 721ms

3 actionable tasks: 1 executed, 2 up-to-date

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