Java 如何访问arraylist的元素<;类别>;
您好,我想知道如何在java中访问arraylist的元素? 我有这门课Java 如何访问arraylist的元素<;类别>;,java,class,arraylist,Java,Class,Arraylist,您好,我想知道如何在java中访问arraylist的元素? 我有这门课 class flight { public String start; public String end; public int timethatend ; public int timethatstart; flight ( int ts , int tf , String s , String e ) { this.start = s;
class flight
{
public String start;
public String end;
public int timethatend ;
public int timethatstart;
flight ( int ts , int tf , String s , String e )
{
this.start = s;
this.end =e;
this.timethatend = tf;
this.timethatstart = ts;
}
}
我的主课上有一个arraylist
ArrayList<flight>list = new ArrayList<flight>();
但问题是这个
flight@1f96302
我该怎么办?
另一个问题是如何更改它们,例如,我想更改第一次飞行的起飞时间。这是打印飞行对象的对象引用。您需要向Flight类添加一个toString()方法,并使用它打印航班信息。例如:
public String toString() {
return start + "," + timethatstart + "," + end + "," + timethatend;
}
打印时:
System.out.println(list.get(0).toString());
在类中添加toString方法,如下所示:
class flight
{
public String start;
public String end;
public int timethatend ;
public int timethatstart;
flight ( int ts , int tf , String s , String e )
{
this.start = s;
this.end =e;
this.timethatend = tf;
this.timethatstart = ts;
}
@Override
public String toString() {
return "flight{" +
"start='" + start + '\'' +
", end='" + end + '\'' +
", timethatend=" + timethatend +
", timethatstart=" + timethatstart +
'}';
}
}
要在arraylist中添加新的航班元素,请执行以下操作:
flight f = new flight(1,2,"12","34");
ArrayList<flight> list = new ArrayList<flight>();
list.add(f);
list.get(0).start = "1234";
以及我如何通过这些元素来改变它们。例如,对于航班1,我想更改它起飞的时间。我应该怎么做?您正在使用list.get(index)访问元素。您可以直接更改其变量,例如:
list.get(0).timethatstart=2400
,或者使用setter和getter方法。
list.get(0).start = "1234";