Question

我正在使用String split方法，我希望拥有最后一个元素。数组的大小可以改变。

示例：

String one = "Düsseldorf - Zentrum - Günnewig Uebachs"
String two = "Düsseldorf - Madison"

我想拆分上面的字符串并获取最后一项：

lastone = one.split("-")[here the last item] // <- how?
lasttwo = two.split("-")[here the last item] // <- how?

我不知道运行时数组的大小：（

Answer 1

或者你可以在String

上使用lastIndexOf()方法

String last = string.substring(string.lastIndexOf('-') + 1);

Answer 2

将数组保存在局部变量中，并使用数组的length字段查找其长度。减去一个以说明它是基于0的：

String[] bits = one.split("-");
String lastOne = bits[bits.length-1];

Answer 3

使用一个简单但通用的辅助方法，如下所示：

public static <T> T last(T[] array) {
    return array[array.length - 1];
}

你可以改写：

lastone = one.split("-")[..];

为：

lastone = last(one.split("-"));

Answer 4

您可以在Apache Commons中使用StringUtils类：

StringUtils.substringAfterLast(one, "-");

Answer 5

String str = "www.anywebsite.com/folder/subfolder/directory";
int index = str.lastIndexOf('/');
String lastString = str.substring(index +1);

现在lastString的值为"directory"

Answer 6

聚集所有可能的方式!!

使用lastIndexOf()＆amp; Java.lang.String

的substring()种方法

// int firstIndex = str.indexOf( separator );
int lastIndexOf = str.lastIndexOf( separator );
String begningPortion = str.substring( 0, lastIndexOf );
String endPortion = str.substring( lastIndexOf + 1 );
System.out.println("First Portion : " + begningPortion );
System.out.println("Last  Portion : " + endPortion );

split() ^{Java SE 1.4}。将提供的文本拆分为数组。

String[] split = str.split( Pattern.quote( separator ) );
String lastOne = split[split.length-1];
System.out.println("Split Array : "+ lastOne);

How to split String before first comma?

来自数组的Java 8顺序排序stream。

String firstItem = Stream.of( split )
                         .reduce( (first,last) -> first ).get();
String lastItem = Stream.of( split )
                        .reduce( (first,last) -> last ).get();
System.out.println("First Item : "+ firstItem);
System.out.println("Last  Item : "+ lastItem);

Apache Commons Lang ^jar«org.apache.commons.lang3.StringUtils

String afterLast = StringUtils.substringAfterLast(str, separator);
System.out.println("StringUtils AfterLast : "+ afterLast);

String beforeLast = StringUtils.substringBeforeLast(str, separator);
System.out.println("StringUtils BeforeLast : "+ beforeLast);

String open = "[", close = "]";
String[] groups = StringUtils.substringsBetween("Yash[777]Sam[7]", open, close);
System.out.println("String that is nested in between two Strings "+ groups[0]);

Guava：适用于Java的Google核心库。 «com.google.common.base.Splitter

Splitter splitter = Splitter.on( separator ).trimResults();
Iterable<String> iterable = splitter.split( str );
String first_Iterable = Iterables.getFirst(iterable, "");
String last_Iterable = Iterables.getLast( iterable );
System.out.println(" Guava FirstElement : "+ first_Iterable);
System.out.println(" Guava LastElement  : "+ last_Iterable);

Scripting for the Java Platform«使用Rhino / Nashorn在JVM上运行Javascript

Rhino«Rhino是一个完全用Java编写的JavaScript的开源实现。它通常嵌入到Java应用程序中，以便为最终用户提供脚本。它作为默认的Java脚本引擎嵌入在J2SE 6中。
Nashorn是Oracle使用Java编程语言开发的JavaScript引擎。它基于Da Vinci Machine并已与Java 8一起发布。

Java Scripting Programmer's Guide

public class SplitOperations {
    public static void main(String[] args) {
        String str = "my.file.png.jpeg", separator = ".";
        javascript_Split(str, separator);
    }
    public static void javascript_Split( String str, String separator ) {
        ScriptEngineManager manager = new ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByName("JavaScript");

        // Script Variables « expose java objects as variable to script.
        engine.put("strJS", str);

        // JavaScript code from file
        File file = new File("E:/StringSplit.js");
        // expose File object as variable to script
        engine.put("file", file);

        try {
            engine.eval("print('Script Variables « expose java objects as variable to script.', strJS)");

            // javax.script.Invocable is an optional interface.
            Invocable inv = (Invocable) engine;

            // JavaScript code in a String
            String functions = "function functionName( functionParam ) { print('Hello, ' + functionParam); }";
            engine.eval(functions);
            // invoke the global function named "functionName"
            inv.invokeFunction("functionName", "function Param value!!" );

            // evaluate a script string. The script accesses "file" variable and calls method on it
            engine.eval("print(file.getAbsolutePath())");
            // evaluate JavaScript code from given file - specified by first argument
            engine.eval( new java.io.FileReader( file ) );

            String[] typedArray = (String[]) inv.invokeFunction("splitasJavaArray", str );
            System.out.println("File : Function returns an array : "+ typedArray[1] );

            ScriptObjectMirror scriptObject = (ScriptObjectMirror) inv.invokeFunction("splitasJavaScriptArray", str, separator );
            System.out.println("File : Function return script obj : "+ convert( scriptObject ) );

            Object eval = engine.eval("(function() {return ['a', 'b'];})()");
            Object result = convert(eval);
            System.out.println("Result: {}"+ result);

            // JavaScript code in a String. This code defines a script object 'obj' with one method called 'hello'.
            String objectFunction = "var obj = new Object(); obj.hello = function(name) { print('Hello, ' + name); }";
            engine.eval(objectFunction);
            // get script object on which we want to call the method
            Object object = engine.get("obj");
            inv.invokeMethod(object, "hello", "Yash !!" );

            Object fileObjectFunction = engine.get("objfile");
            inv.invokeMethod(fileObjectFunction, "hello", "Yashwanth !!" );
        } catch (ScriptException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static Object convert(final Object obj) {
        System.out.println("\tJAVASCRIPT OBJECT: {}"+ obj.getClass());
        if (obj instanceof Bindings) {
            try {
                final Class<?> cls = Class.forName("jdk.nashorn.api.scripting.ScriptObjectMirror");
                System.out.println("\tNashorn detected");
                if (cls.isAssignableFrom(obj.getClass())) {
                    final Method isArray = cls.getMethod("isArray");
                    final Object result = isArray.invoke(obj);
                    if (result != null && result.equals(true)) {
                        final Method values = cls.getMethod("values");
                        final Object vals = values.invoke(obj);
                        System.err.println( vals );
                        if (vals instanceof Collection<?>) {
                            final Collection<?> coll = (Collection<?>) vals;
                            Object[] array = coll.toArray(new Object[0]);
                            return array;
                        }
                    }
                }
            } catch (ClassNotFoundException | NoSuchMethodException | SecurityException
                    | IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
            }
        }
        if (obj instanceof List<?>) {
            final List<?> list = (List<?>) obj;
            Object[] array = list.toArray(new Object[0]);
            return array;
        }
        return obj;
    }
}

JavaScript文件«StringSplit.js

// var str = 'angular.1.5.6.js', separator = ".";
function splitasJavaArray( str ) {
  var result = str.replace(/\.([^.]+)$/, ':$1').split(':');
  print('Regex Split : ', result);
  var JavaArray = Java.to(result, "java.lang.String[]");
  return JavaArray;
  // return result;
}
function splitasJavaScriptArray( str, separator) {
    var arr = str.split( separator ); // Split the string using dot as separator
    var lastVal = arr.pop(); // remove from the end
    var firstVal = arr.shift(); // remove from the front
    var middleVal = arr.join( separator ); // Re-join the remaining substrings

    var mainArr = new Array();
    mainArr.push( firstVal ); // add to the end
    mainArr.push( middleVal );
    mainArr.push( lastVal );

    return mainArr;
}

var objfile = new Object();
objfile.hello = function(name) { print('File : Hello, ' + name); }

JavaScript Array constructor or array literal。

Answer 7

使用Guava：

final Splitter splitter = Splitter.on("-").trimResults();
assertEquals("Günnewig Uebachs", Iterables.getLast(splitter.split(one)));
assertEquals("Madison", Iterables.getLast(splitter.split(two)));

Splitter，Iterables

Answer 8

因为他要求使用拆分在同一行中完成所有操作，所以我建议：

lastone = one.split("-")[(one.split("-")).length -1]

我总是尽量避免定义新的变量，我发现这是一个非常好的做法

Answer 9

你的意思是你在编译时不知道数组的大小？在运行时，可以通过lastone.length和lastwo.length的值找到它们。

Answer 10

在java 8中

String lastItem = Stream.of(str.split("-")).reduce((first,last)->last).get();

Answer 11

我想你想在i行做这个。这有可能（虽然有点杂乱= ^）

new StringBuilder(new StringBuilder("Düsseldorf - Zentrum - Günnewig Uebachs").reverse().toString().split(" - ")[0]).reverse()

tadaa，一行 - ＆gt;你想要的结果（如果你拆分“ - ”（空间减去空间）而不是只有“ - ”（减号）你将在分区之前松开恼人的空间= ^）所以“GünnewigUebachs”而不是“GünnewigUebachs” （以空格作为第一个字符）

好的额外 - ＆gt; lib文件夹中不需要额外的JAR文件，因此您可以保持应用程序的轻量化。

Answer 12

您也可以使用java.util.ArrayDeque

String last = new ArrayDeque<>(Arrays.asList("1-2".split("-"))).getLast();

Java：拆分后获取最后一个元素

12 个答案: