死循環了什么問題啊

import?java.lang.reflect.Array;
import?java.util.ArrayList;
import?java.util.Arrays;
import?java.util.List;

/**
?*?備選課程類
?*/
public?class?ListTest?{

????public?List?coursesToSelect;

????public?ListTest()?{
????????this.coursesToSelect?=?new?ArrayList();

????}

????/**
??????*/
????public?void?testAdd(){
??????Courses?cr1?=?new?Courses("1","數據結構")?;
??????coursesToSelect.add(cr1);
??????Courses?temp?=?(Courses)?coursesToSelect.get(0);
??????System.out.println("添加了課程："?+temp.id?+":"+?temp.name??);

??????Courses?cr2?=?new?Courses("王澤宇","健身只打卡");
??????coursesToSelect.add(0,cr2);
??????Courses?temp2?=?(Courses)?coursesToSelect.get(0);
??????System.out.println("添加了課程："?+temp2.id?+":"+?temp2.name??);


????????Courses[]course?=?{new?Courses("3","java"?),new?Courses("4","匯編語言")};
????????coursesToSelect.addAll(Arrays.asList(course));
????????Courses?temp3?=?(Courses)coursesToSelect.get(2);
????????Courses?temp4?=?(Courses)coursesToSelect.get(3);

????????System.out.println("添加了兩門課程："?+?temp3.id+?":"+temp3.name?+";"?+?temp4.id+":"+temp4.name);
????????ListTest?lt?=?new?ListTest();
????????lt.testAdd();





????}

????public?static?void?main(String[]?args)?{
????????ListTest?lt?=?new?ListTest();
????????lt.testAdd();
????}
}