/**
   * 使用增強(qiáng)的for循環(huán)
   * 在循環(huán)過程中從List中刪除元素以后，繼續(xù)循環(huán)List時(shí)會(huì)報(bào)ConcurrentModificationException
   */
  public void listRemove() {
    List<Student> students = this.getStudents();
    for (Student stu : students) {
      if (stu.getId() == 2) 
        students.remove(stu);
    }
  }

/**
   * 像這種使用增強(qiáng)的for循環(huán)對(duì)List進(jìn)行遍歷刪除，但刪除之后馬上就跳出的也不會(huì)出現(xiàn)異常
   */
  public void listRemoveBreak() {
    List<Student> students = this.getStudents();
    for (Student stu : students) {
      if (stu.getId() == 2) {
        students.remove(stu);
        break;
      }
    }
  }

/**
   * 這種遍歷有可能會(huì)遺漏某個(gè)元素,因?yàn)閯h除元素后List的size在
   * 變化，元素的索引也在變化，比如你循環(huán)到第2個(gè)元素的時(shí)候你把它刪了，
   * 接下來你去訪問第3個(gè)元素，實(shí)際上訪問到的是原先的第4個(gè)元素。當(dāng)訪問的元素
   * 索引超過了當(dāng)前的List的size后還會(huì)出現(xiàn)數(shù)組越界的異常，當(dāng)然這里不會(huì)出現(xiàn)這種異常，
   * 因?yàn)檫@里每遍歷一次都重新拿了一次當(dāng)前List的size。
   */
  public void listRemove2() {
    List<Student> students = this.getStudents();
    for (int i=0; i<students.size(); i++) {
      if (students.get(i).getId()%3 == 0) {
        Student student = students.get(i);
        students.remove(student);
      }
    }
  }

/**
   * 使用Iterator的方式也可以順利刪除和遍歷
   */
  public void iteratorRemove() {
    List<Student> students = this.getStudents();
    System.out.println(students);
    Iterator<Student> stuIter = students.iterator();
    while (stuIter.hasNext()) {
      Student student = stuIter.next();
      if (student.getId() % 2 == 0)
//這里要使用Iterator的remove方法移除當(dāng)前對(duì)象，如果使用List的remove方法，則同樣會(huì)出現(xiàn)ConcurrentModificationException
        stuIter.remove();
    }
    System.out.println(students);
  }

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class ListRemove {

  public static void main(String args[]) {
    ListRemove lr = new ListRemove();
    lr.listRemove();
    lr.listRemoveBreak();
//    lr.listRemove2();
//    lr.iteratorRemove();
  }

  /**
   * 使用增強(qiáng)的for循環(huán)
   * 在循環(huán)過程中從List中刪除元素以后，繼續(xù)循環(huán)List時(shí)會(huì)報(bào)ConcurrentModificationException
   */
  public void listRemove() {
    List<Student> students = this.getStudents();
    for (Student stu : students) {
      if (stu.getId() == 2) 
        students.remove(stu);
    }
  }
  
  /**
   * 像這種使用增強(qiáng)的for循環(huán)對(duì)List進(jìn)行遍歷刪除，但刪除之后馬上就跳出的也不會(huì)出現(xiàn)異常
   */
  public void listRemoveBreak() {
    List<Student> students = this.getStudents();
    for (Student stu : students) {
      if (stu.getId() == 2) {
        students.remove(stu);
        break;
      }
    }
  }
  
  /**
   * 這種不使用增強(qiáng)的for循環(huán)，每次重新獲取list的size遍歷的情況運(yùn)行時(shí)不會(huì)報(bào)錯(cuò)，但是可能刪除的結(jié)果是錯(cuò)的。
   */
  public void listRemove2() {
    List<Student> students = this.getStudents();
    for (int i=0; i<students.size(); i++) {
      if (students.get(i).getId()%2 == 0)
        students.remove(i);
    }
  }
  
  /**
   * 使用Iterator的方式也可以順利刪除和遍歷
   */
  public void iteratorRemove() {
    List<Student> students = this.getStudents();
    System.out.println(students);
    Iterator<Student> stuIter = students.iterator();
    while (stuIter.hasNext()) {
      Student student = stuIter.next();
      if (student.getId() % 2 == 0)
        stuIter.remove();
    }
    System.out.println(students);
  }
  
  private List<Student> getStudents() {
    List<Student> students = new ArrayList<Student>() {
      {
        int i = 0;
        while (i++ < 10) {
          Student student = new Student(i, "201200" + i, "name_" + i);
          this.add(student);
        }
      }
    };
    return students;
  }
}

public class Student {

  private int id;
  private String stuNo;
  private String name;
  
  public Student() {
    
  }
  
  public Student(int id, String stuNo, String name) {
    this.id = id;
    this.stuNo = stuNo;
    this.name = name;
  }

  public int getId() {
    return id;
  }

  public void setId(int id) {
    this.id = id;
  }

  public String getStuNo() {
    return stuNo;
  }

  public void setStuNo(String stuNo) {
    this.stuNo = stuNo;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  @Override
  public String toString() {
    return "Student [id=" + id + ", name=" + name + ", stuNo=" + stuNo
        + "]";
  }
  
}