标准JDK类库里面没有这个API,第三方的类库当中可能有,具体实现也是for循环一个一个装换的 不过如果对象数组里面全部都是String,如果仅仅是要输出信息的话,可以不转换 import java.util.List;/** * Created by IntelliJ IDEA. * User: admin * Date: 2011-10-12 * Time: 10:55:57 * To change this template use File | Settings | File Templates. */ public class TransferStrAry { public static void main(String[] args) { Object[] os={"a","b","c"}; // List list=o. for(Object o:os){ System.out.println("out:"+o); } } } 如果用利用String做拼接连缀等处理就必须转换了
List list = new ArrayList(); list.add("asdfasdf"); list.add("sfh"); list.add("345"); String[] str = (String[])list.toArray(); System.out.println(str.length);报这个 Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; at com.ruanko.service.certificate.impl.CertificateReviewManagerImpl.main(CertificateReviewManagerImpl.java:35)
即使是一些工具类也是用for来一个一个转的
不过如果对象数组里面全部都是String,如果仅仅是要输出信息的话,可以不转换
import java.util.List;/**
* Created by IntelliJ IDEA.
* User: admin
* Date: 2011-10-12
* Time: 10:55:57
* To change this template use File | Settings | File Templates.
*/
public class TransferStrAry {
public static void main(String[] args) {
Object[] os={"a","b","c"};
// List list=o.
for(Object o:os){
System.out.println("out:"+o);
}
}
}
如果用利用String做拼接连缀等处理就必须转换了
List list = new ArrayList();
list.add("asdfasdf");
list.add("sfh");
list.add("345");
String[] str = (String[])list.toArray();
System.out.println(str.length);报这个
Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object;
at com.ruanko.service.certificate.impl.CertificateReviewManagerImpl.main(CertificateReviewManagerImpl.java:35)
如果类似将list转成String[],即list.toArray(new String[0]);
import java.util.ArrayList;public class TransferStrAry {
public static void main(String[] args) {
List list = new ArrayList();
list.add("asdfasdf");
list.add("sfh");
list.add("345");
String[] str =new String[list.size()];
list.toArray(str);
for(String s:str){
System.out.println(s);
}
}
}
List list = new ArrayList();
list.add("asdfasdf");
list.add("sfh");
list.add("345");
String[] str = (String[]) list.toArray(new String[0]);
System.out.println(str.length);
4F正解!