我需要在Java中连接两个字符串数组。
void f(String[] first, String[] second) {
String[] both = ???
}
哪种方法最简单?
我需要在Java中连接两个字符串数组。
void f(String[] first, String[] second) {
String[] both = ???
}
哪种方法最简单?
当前回答
/**
* With Java Streams
* @param first First Array
* @param second Second Array
* @return Merged Array
*/
String[] mergeArrayOfStrings(String[] first, String[] second) {
return Stream.concat(Arrays.stream(first), Arrays.stream(second)).toArray(String[]::new);
}
其他回答
这是算盘常用的密码。
String[] a = {"a", "b", "c"};
String[] b = {"1", "2", "3"};
String[] c = N.concat(a, b); // c = ["a", "b", "c", "1", "2", "3"]
// N.concat(...) is null-safety.
a = null;
c = N.concat(a, b); // c = ["1", "2", "3"]
只是想添加,您也可以使用System.arraycopy:
import static java.lang.System.out;
import static java.lang.System.arraycopy;
import java.lang.reflect.Array;
class Playground {
@SuppressWarnings("unchecked")
public static <T>T[] combineArrays(T[] a1, T[] a2) {
T[] result = (T[]) Array.newInstance(a1.getClass().getComponentType(), a1.length+a2.length);
arraycopy(a1,0,result,0,a1.length);
arraycopy(a2,0,result,a1.length,a2.length);
return result;
}
public static void main(String[ ] args) {
String monthsString = "JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC";
String[] months = monthsString.split("(?<=\\G.{3})");
String daysString = "SUNMONTUEWEDTHUFRISAT";
String[] days = daysString.split("(?<=\\G.{3})");
for (String m : months) {
out.println(m);
}
out.println("===");
for (String d : days) {
out.println(d);
}
out.println("===");
String[] results = combineArrays(months, days);
for (String r : results) {
out.println(r);
}
out.println("===");
}
}
我从老的Apache Commons Lang库中找到了一个单行解决方案。ArrayUtils.addAll(T[],T…)
代码:
String[] both = ArrayUtils.addAll(first, second);
这是字符串数组的转换函数:
public String[] mergeArrays(String[] mainArray, String[] addArray) {
String[] finalArray = new String[mainArray.length + addArray.length];
System.arraycopy(mainArray, 0, finalArray, 0, mainArray.length);
System.arraycopy(addArray, 0, finalArray, mainArray.length, addArray.length);
return finalArray;
}
使用流的Java8的另一种方式
public String[] concatString(String[] a, String[] b){
Stream<String> streamA = Arrays.stream(a);
Stream<String> streamB = Arrays.stream(b);
return Stream.concat(streamA, streamB).toArray(String[]::new);
}