在Java / Groovy中将数组转换为字符串

Convert Array to string in Java/ groovy

我有一个这样的清单：

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List tripIds = new ArrayList()
def sql = Sql.newInstance("jdbc:mysql://localhost:3306/steer","root",
"","com.mysql.jdbc.Driver")
sql.eachRow("SELECT trip.id from trip JOIN department WHERE organization_id = trip.client_id AND department.id =1") {
println"Gromit likes ${it.id}"
tripIds << it.id
}

现在在打印三叉戟给我带来价值

1	[1,2,3,4,5,6,]

现在我想将此列表转换为简单的字符串，如

1	1,2,3,4,5,6

我该怎么做

使用join，例如

1	tripIds.join(",")

无关，但是如果您只想从另一个列表中创建一个列表，则最好做一个map或collect之类的操作，而不是手动创建一个列表并将其附加到列表上，这是比较惯用的，例如 (未测试)，

1 2	def sql = Sql.newInstance("jdbc:mysql://localhost:3306/steer","root","","com.mysql.jdbc.Driver") def tripIds = sql.map { it.id }

或者，如果您只关心结果字符串，

1	def tripIds = sql.map { it.id }.join(",")

时髦：

1 2	def myList = [1,2,3,4,5] def asString = myList.join(",")

使用Groovy添加到Collection的join方法

1 2	List l = [1,2,3,4,5,6] assert l.join(',') =="1,2,3,4,5,6"

1 2	String str = tripIds.toString(); str = str.substring(1, str.length() - 1);

您可以尝试以下方法将列表转换为字符串

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StringBuffer sb = new StringBuffer();
for (int i=0; i<tripIds.size(); i++)
{
if(i!=0){
sb.append(",").append(tripIds.get(i));
}else{
sb.append(tripIds.get(i));
}
}
String listInString = sb.toString();
System.out.println(listInString);

例

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ArrayList<String> tripIds = new ArrayList<String>();
tripIds.add("a");
tripIds.add("b");
tripIds.add("c");
StringBuffer sb = new StringBuffer();
for (int i=0; i<tripIds.size(); i++)
{
if(i!=0){
sb.append(",").append(tripIds.get(i));
}else{
sb.append(tripIds.get(i));
}
}
String listInString = sb.toString();
System.out.println(listInString);