Launches an Ant build with default settings什么意思

“Launches an Ant build with default settings” 的意思是使用默认设置启动一个 Ant 构建。这意味着在构建过程中，Ant 将使用默认的构建文件 `build.xml`，默认的构建目标（如果没有指定），以及默认的构建选项（如果没有在构建文件中设置）。

默认情况下，Ant 使用与 `build.xml` 文件相同的目录作为构建目录，并将输出和日志信息写入控制台。你可以通过在命令行中指定不同的构建文件、构建目标、构建选项等来更改默认设置。

例如，可以使用以下命令启动一个 Ant 构建，其中 `myBuild.xml` 是构建文件，`build` 是构建目标：

ant -f myBuild.xml build

这将使用 `myBuild.xml` 文件作为构建文件，并执行 `build` 目标。

相关问题

A simple Android application consists of two Activity components. The first, MainActivity, contains a String and an Integer. It also displays a button that, when pressed, launches SecondActivity via an explicit Intent. The user launches the application, then presses the button, and then presses the back button. i. Describe the life-cycle calls that these two Activities would receive, and in what order they would receive them. You should illustrate your answer with a diagram of the Activity stack as it changes over time.

The lifecycle calls for the two activities would be as follows:

1. MainActivity: onCreate() -> onStart() -> onResume()
2. SecondActivity: onCreate() -> onStart() -> onResume()
3. MainActivity: onPause() -> onStop()
4. SecondActivity: onPause() -> onStop() -> onDestroy()
5. MainActivity: onRestart() -> onStart() -> onResume()
6. MainActivity: onPause() -> onStop() -> onDestroy()

The diagram of the Activity stack as it changes over time would look like this:

|               |
|    MainActivity    |  // created, started, and resumed
|               |
|---------------|
|               |
|   SecondActivity   |  // created, started, and resumed
|               |
|---------------|
|               |
|    MainActivity    |  // paused and stopped
|               |
|---------------|
|               |
|   SecondActivity   |  // paused, stopped, and destroyed
|               |
|---------------|
|               |
|    MainActivity    |  // restarted, started, and resumed
|               |
|---------------|
|               |
|    MainActivity    |  // paused, stopped, and destroyed
|               |
|---------------|

Write a program that launches 1,000 threads. Each thread adds 1 to an integer variable sum which initialized as 0. Implement the addition program with and without synchronization to observe different results. (1)Define the main class sum to create a fixed thread pool with 1,000 threads; (2)Define the task class SumTaskWithoutSyn which implements addition without any synchronization; (3)Define the task class SumTaskWithSynMet to implement synchronized method; (4)Define the task class SumTaskWithSynStat to implement synchronized statement block; (5)Define the task class SumTaskWithLock to implement synchronization with lock.

Sure, I can help you with that.

Here is the code for the main class `Sum`:

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Sum {
    public static void main(String[] args) {
        int threadCount = 1000;
        int sum = 0;

        ExecutorService executor = Executors.newFixedThreadPool(threadCount);

        // Create 1000 threads and submit SumTaskWithoutSyn tasks
        for (int i = 0; i < threadCount; i++) {
            executor.execute(new SumTaskWithoutSyn(sum));
        }

        // Shutdown the executor
        executor.shutdown();

        // Wait until all threads are finished
        while (!executor.isTerminated()) {
        }

        System.out.println("Sum without synchronization: " + sum);

        // Reset the sum variable
        sum = 0;

        // Create a new executor
        executor = Executors.newFixedThreadPool(threadCount);

        // Create 1000 threads and submit SumTaskWithSynMet tasks
        for (int i = 0; i < threadCount; i++) {
            executor.execute(new SumTaskWithSynMet(sum));
        }

        // Shutdown the executor
        executor.shutdown();

        // Wait until all threads are finished
        while (!executor.isTerminated()) {
        }

        System.out.println("Sum with synchronized method: " + sum);

        // Reset the sum variable
        sum = 0;

        // Create a new executor
        executor = Executors.newFixedThreadPool(threadCount);

        // Create 1000 threads and submit SumTaskWithSynStat tasks
        for (int i = 0; i < threadCount; i++) {
            executor.execute(new SumTaskWithSynStat(sum));
        }

        // Shutdown the executor
        executor.shutdown();

        // Wait until all threads are finished
        while (!executor.isTerminated()) {
        }

        System.out.println("Sum with synchronized statement block: " + sum);

        // Reset the sum variable
        sum = 0;

        // Create a new executor
        executor = Executors.newFixedThreadPool(threadCount);

        // Create 1000 threads and submit SumTaskWithLock tasks
        for (int i = 0; i < threadCount; i++) {
            executor.execute(new SumTaskWithLock(sum));
        }

        // Shutdown the executor
        executor.shutdown();

        // Wait until all threads are finished
        while (!executor.isTerminated()) {
        }

        System.out.println("Sum with lock synchronization: " + sum);
    }
}

The `Sum` class creates a fixed thread pool with 1,000 threads and submits tasks to the executor. It then waits for all threads to finish and prints the final sum.

Here is the code for the `SumTaskWithoutSyn` class:

public class SumTaskWithoutSyn implements Runnable {
    private int sum;

    public SumTaskWithoutSyn(int sum) {
        this.sum = sum;
    }

    @Override
    public void run() {
        sum += 1;
    }
}

The `SumTaskWithoutSyn` class implements the addition without any synchronization.

Here is the code for the `SumTaskWithSynMet` class:

public class SumTaskWithSynMet implements Runnable {
    private int sum;

    public SumTaskWithSynMet(int sum) {
        this.sum = sum;
    }

    @Override
    public void run() {
        add();
    }

    private synchronized void add() {
        sum += 1;
    }
}

The `SumTaskWithSynMet` class implements the addition with synchronized method.

Here is the code for the `SumTaskWithSynStat` class:

public class SumTaskWithSynStat implements Runnable {
    private int sum;

    public SumTaskWithSynStat(int sum) {
        this.sum = sum;
    }

    @Override
    public void run() {
        synchronized (this) {
            sum += 1;
        }
    }
}

The `SumTaskWithSynStat` class implements the addition with synchronized statement block.

Here is the code for the `SumTaskWithLock` class:

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class SumTaskWithLock implements Runnable {
    private int sum;
    private Lock lock;

    public SumTaskWithLock(int sum) {
        this.sum = sum;
        lock = new ReentrantLock();
    }

    @Override
    public void run() {
        lock.lock();
        try {
            sum += 1;
        } finally {
            lock.unlock();
        }
    }
}

The `SumTaskWithLock` class implements the addition with lock synchronization.

I hope this helps!