12 posts tagged with "java"

long l = 1234567890L;
int i = (int) l; // 数据截断，i的值为-53922298

long l = 1234567890L;
int i = Math.toIntExact(l); // i的值为1234567890

import groovy.util.Node
import groovy.util.NodeList
import groovy.util.XmlParser

public class GradleDependencyParser {

    public static void main(String[] args) {
        String buildFilePath = "path/to/build.gradle";
        GradleDependencyParser parser = new GradleDependencyParser();
        parser.parse(buildFilePath);
    }

    public void parse(String buildFilePath) {
        XmlParser parser = new XmlParser(false, false);
        Node rootNode = parser.parse(new File(buildFilePath));
        NodeList dependencies = rootNode.depthFirst().findAll { it.name() == 'dependencies' }[0];
        dependencies.children().each { dependency ->
            String group = dependency.attributes().get("group");
            String name = dependency.attributes().get("name");
            String version = dependency.attributes().get("version");
            System.out.println("Group: " + group + ", Name: " + name + ", Version: " + version);
        }
    }
}

import groovy.util.Node
import groovy.util.NodeList
import groovy.util.XmlParser
import org.jetbrains.kotlin.script.jsr223.KotlinJsr223JvmLocalScriptEngineFactory
import javax.script.ScriptEngine

public class KotlinGradleDependencyParser {

    public static void main(String[] args) {
        String buildFilePath = "path/to/build.gradle.kts";
        KotlinGradleDependencyParser parser = new KotlinGradleDependencyParser();
        parser.parse(buildFilePath);
    }

    public void parse(String buildFilePath) {
        ScriptEngine engine = new KotlinJsr223JvmLocalScriptEngineFactory().scriptEngine
        engine.eval("file(\"" + buildFilePath + "\").readText()")
        String dependencies = (String) engine.eval("kotlin.runCatching {"
                + "val deps = arrayListOf<String>()\n"
                + "dependencies {\n"
                + "  classpath.forEach { dep -> deps.add(\"${dep.group}:${dep.name}:${dep.version}\") }\n"
                + "}\n"
                + "deps.joinToString(\"\n\")"
                + "}.getOrNull()");
        System.out.println(dependencies);
    }
}

List<Integer> list = new ArrayList<>();
list.add(1);
list.add(2);
list.add(3);
System.out.println("翻转前:" + list);
Collections.reverse(list);
System.out.println("反转后:" + list);

    public static void main(String[] args) {
        Integer a = 127;
        Integer b = 127;
        System.out.println(a == b); // true
        System.out.println(a.equals(b)); // true

        Integer c = 128;
        Integer d = 128;
        System.out.println(c == d); // false
        System.out.println(c.equals(d)); // true
    }

    /**
     * Cache to support the object identity semantics of autoboxing for values between
     * -128 and 127 (inclusive) as required by JLS.
     *
     * The cache is initialized on first usage.  The size of the cache
     * may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option.
     * During VM initialization, java.lang.Integer.IntegerCache.high property
     * may be set and saved in the private system properties in the
     * sun.misc.VM class.
     */

    private static class IntegerCache {
        static final int low = -128;
        static final int high;
        static final Integer cache[];

        static {
            // high value may be configured by property
            int h = 127;
            String integerCacheHighPropValue =
                sun.misc.VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
            if (integerCacheHighPropValue != null) {
                try {
                    int i = parseInt(integerCacheHighPropValue);
                    i = Math.max(i, 127);
                    // Maximum array size is Integer.MAX_VALUE
                    h = Math.min(i, Integer.MAX_VALUE - (-low) -1);
                } catch( NumberFormatException nfe) {
                    // If the property cannot be parsed into an int, ignore it.
                }
            }
            high = h;

            cache = new Integer[(high - low) + 1];
            int j = low;
            for(int k = 0; k < cache.length; k++)
                cache[k] = new Integer(j++);

            // range [-128, 127] must be interned (JLS7 5.1.7)
            assert IntegerCache.high >= 127;
        }

        private IntegerCache() {}
    }

    /**
     * Returns an {@code Integer} instance representing the specified
     * {@code int} value.  If a new {@code Integer} instance is not
     * required, this method should generally be used in preference to
     * the constructor {@link #Integer(int)}, as this method is likely
     * to yield significantly better space and time performance by
     * caching frequently requested values.
     *
     * This method will always cache values in the range -128 to 127,
     * inclusive, and may cache other values outside of this range.
     *
     * @param  i an {@code int} value.
     * @return an {@code Integer} instance representing {@code i}.
     * @since  1.5
     */
    public static Integer valueOf(int i) {
        if (i >= IntegerCache.low && i <= IntegerCache.high)
            return IntegerCache.cache[i + (-IntegerCache.low)];
        return new Integer(i);
    }