java - 如何从ArrayList中获取所需的格式

Question

import java.net.UnknownHostException;
import java.text.DecimalFormat;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.List;

import org.apache.log4j.Logger;

public class Test {
    final static Logger logger = Logger.getLogger(Test.class);
    private static DecimalFormat decimal_inpoints = new DecimalFormat("0.00");

    public static void main(String args[]) throws UnknownHostException,
            ParseException {

        ArrayList<Integer> array_list = new ArrayList<Integer>();

        array_list.add(1);
        array_list.add(0);

        String joinedString = array_list.toString();

        System.out.println(joinedString);

    }

}

如何将输出设为 1,0

当我使用 array_list.toString() 时；其给出的输入为 [1,0](已添加数组)

你能告诉我如何得到 1,0 而不是 [1,0]

Answer 1

使用Apache Commons Lang :

String join = StringUtils.join(joinList, ",");

使用 Java 8

String joined = String.join(",", list);

使用 Google Guava (Joiner)

Joiner joiner = Joiner.on(",");
String join = joiner.join(joinList);

使用 StringBuilder

StringBuilder builder = new StringBuilder(array_list.size());
boolean isFirst = true;
for (int i : array_list){
  if (isFirst) {
    builder.append(i);
    isFirst = false;
  } else {
    builder.append(", " + i);
  }
}
System.out.println(builder.toString());