我不明白为什么我的变量会重置为默认值。我单击listView，它将变量currentAssessment设置为所检索记录的ID。然后，我单击以删除具有所选ID的记录，并且该记录已被重置。
package com.breathetaichi.classtracker;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
public class CourseActivity extends AppCompatActivity {
private static DBInterface db;
private static ArrayList<Course> allCourses = new ArrayList<>();
private static ArrayList<Assessment> allAssessments = new ArrayList<>();
private static ArrayList<Instructor> allInstructors = new ArrayList<>();
private int courseCalled;
private int currentAssessment = -1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_course);
// currentAssessment = -1;
db = new DBInterface(CourseActivity.this);
db.getWritableDatabase();
allCourses = db.getCourses();
allAssessments = db.getAssessments();
allInstructors = db.getInstructors();
Bundle extras = getIntent().getExtras();
courseCalled = extras.getInt("courseID");
String courseTitle = "";
int courseTermID = -1;
int courseInstructorID = -1;
String courseStartDateStr = "";
String courseEndDateStr = "";
String courseStatusStr = "";
String courseNoteStr = "";
for(Course course : allCourses) {
if(course.getId() == courseCalled) {
courseTitle = course.getTitle();
courseTermID = course.getTermID();
courseInstructorID = course.getInstructorID();
courseStartDateStr = course.getStartDate();
courseEndDateStr = course.getEndDate();
courseStatusStr = course.getStatus();
courseNoteStr = course.getNote();
}
}
EditText courseName = findViewById(R.id.course_title);
courseName.setText(courseTitle);
EditText courseStartDate = findViewById(R.id.course_start_date);
courseStartDate.setText(courseStartDateStr);
EditText courseEndDate = findViewById(R.id.course_end_date);
courseEndDate.setText(courseEndDateStr);
EditText courseStatus = findViewById(R.id.course_status);
courseStatus.setText(courseStatusStr);
EditText termEndDate = findViewById(R.id.course_note);
termEndDate.setText(courseNoteStr);
int instructorID = courseInstructorID;
String instructorNameStr = "";
String instructorPhoneStr = "";
String instructorEmailStr = "";
for (Instructor instructor : allInstructors) {
if(instructor.getId() == instructorID) {
instructorNameStr = instructor.getName();
instructorPhoneStr = instructor.getPhone();
instructorEmailStr = instructor.getEmail();
}
}
EditText instructorName = findViewById(R.id.instructor_name);
instructorName.setText(instructorNameStr);
EditText instructorPhone = findViewById(R.id.instructor_phone);
instructorPhone.setText(instructorPhoneStr);
EditText instructorEmail = findViewById(R.id.instructor_email);
instructorEmail.setText(instructorEmailStr);
List<Assessment> assessmentsInCourse = new ArrayList<>();
for (Assessment assessment : allAssessments) {
if(assessment.getCourseID() == courseCalled) {
assessmentsInCourse.add(assessment);
}
}
String[] titles = new String[assessmentsInCourse.size()];
final int[] assessmentIDs = new int[assessmentsInCourse.size()];
int i = 0;
for(Assessment assessment : assessmentsInCourse) {
titles[i] = assessment.getTitle();
assessmentIDs[i] = assessment.getId();
i++;
}
final android.widget.ListAdapter adapter = new ListAdapter(this, titles);
final ListView lv = findViewById(R.id.assessment_list_view);
lv.setAdapter(adapter);
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
int currentAssessment = assessmentIDs[(int)id];
System.out.println("set to clicked id, currentAssessment = " + currentAssessment);
Assessment assessment = getAssessment(currentAssessment);
String assessmentNameStr = assessment.getTitle();
String assessmentTypeStr = assessment.getType();
String assessmentDueStr = assessment.getDueDate();
EditText assessmentName = findViewById(R.id.assessment_title);
assessmentName.setText(assessmentNameStr);
EditText assessmentType = findViewById(R.id.assessment_type);
assessmentType.setText(assessmentTypeStr);
EditText assessmentDue = findViewById(R.id.assessment_due);
assessmentDue.setText(assessmentDueStr);
System.out.println("end of onclickListener, currentAssessment = " + currentAssessment);
}
});
System.out.println("After listener, currentAssessment = " + currentAssessment);
}
public void deleteCourseButton(View v) {
if(courseCalled == -1) {
Toast.makeText(CourseActivity.this,
"No saved term to delete,\nplease use back button.",
Toast.LENGTH_SHORT).show();
} else {
for(Course course : allCourses) {
if(course.getId() == courseCalled) {
db.deleteCourse(courseCalled);
TermActivity.numberOfCourses--;
}
}
this.recreate();
}
}
public void saveCourseButton(View v) {
Course saveCourse = new Course();
for(Course course : allCourses) {
if(courseCalled == course.getId()) {
saveCourse = course;
}
}
String courseTitle;
int courseTermID = saveCourse.getTermID();
int courseInstructorID = saveCourse.getInstructorID();
String courseStartDateStr;
String courseEndDateStr;
String courseStatusStr;
String courseNoteStr;
EditText courseName = findViewById(R.id.course_title);
courseTitle = courseName.getText().toString();
EditText courseStartDate = findViewById(R.id.course_start_date);
courseStartDateStr = courseStartDate.getText().toString();
EditText courseEndDate = findViewById(R.id.course_end_date);
courseEndDateStr = courseEndDate.getText().toString();
EditText courseStatus = findViewById(R.id.course_status);
courseStatusStr = courseStatus.getText().toString();
EditText courseNote = findViewById(R.id.course_note);
courseNoteStr = courseNote.getText().toString();
String instructorNameStr;
String instructorPhoneStr;
String instructorEmailStr;
EditText instructorName = findViewById(R.id.instructor_name);
instructorNameStr = instructorName.getText().toString();
EditText instructorPhone = findViewById(R.id.instructor_phone);
instructorPhoneStr = instructorPhone.getText().toString();
EditText instructorEmail = findViewById(R.id.instructor_email);
instructorEmailStr = instructorEmail.getText().toString();
if(courseTitle.isEmpty()
|| courseStartDateStr.isEmpty()
|| courseEndDateStr.isEmpty()
|| courseStatusStr.isEmpty()
|| courseNoteStr.isEmpty()) {
Toast.makeText(CourseActivity.this, "Please fill course fields.",
Toast.LENGTH_SHORT).show();
} else if(instructorNameStr.isEmpty()
|| instructorPhoneStr.isEmpty()
|| instructorEmailStr.isEmpty()) {
Toast.makeText(CourseActivity.this, "Please fill instructor fields.",
Toast.LENGTH_SHORT).show();
} else {
// Check if new course courseCalled is -1 or if not update with id in courseCalled
if(courseCalled == -1) {
courseTermID = TermActivity.activeTerm.getId();
// Insert new instructor and get their ID back
courseInstructorID = (int) db.insertInstructor(instructorNameStr,
instructorPhoneStr, instructorEmailStr);
courseCalled = (int) db.insertCourse(courseTermID,
courseInstructorID, courseTitle, courseStartDateStr,
courseEndDateStr, courseStatusStr, courseNoteStr);
allCourses = db.getCourses();
Toast.makeText(CourseActivity.this, "New course saved.",
Toast.LENGTH_SHORT).show();
this.recreate();
} else {
// Insert new instructor and get their ID back
courseInstructorID = (int) db.insertInstructor(instructorNameStr,
instructorPhoneStr, instructorEmailStr);
db.updateCourse(courseCalled, courseTermID, courseInstructorID, courseTitle,
courseStartDateStr, courseEndDateStr, courseStatusStr, courseNoteStr);
allCourses = db.getCourses();
Toast.makeText(CourseActivity.this, "Course updated.",
Toast.LENGTH_SHORT).show();
this.recreate();
}
}
}
public void saveAssessmentButton(View v) {
String assessmentNameStr;
String assessmentTypeStr;
String assessmentDueStr;
EditText assessmentName = findViewById(R.id.assessment_title);
assessmentNameStr = assessmentName.getText().toString();
EditText assessmentType = findViewById(R.id.assessment_type);
assessmentTypeStr = assessmentType.getText().toString();
EditText assessmentDue = findViewById(R.id.assessment_due);
assessmentDueStr = assessmentDue.getText().toString();
if(assessmentDueStr.isEmpty() || assessmentNameStr.isEmpty() || assessmentTypeStr.isEmpty()) {
Toast.makeText(CourseActivity.this, "Please fill all fields.",
Toast.LENGTH_SHORT).show();
} else {
if (currentAssessment == -1) {
currentAssessment = (int) db.insertAssessment(courseCalled, assessmentNameStr,
assessmentTypeStr, assessmentDueStr);
allAssessments = db.getAssessments();
Toast.makeText(CourseActivity.this, "Assessment added.",
Toast.LENGTH_SHORT).show();
this.recreate();
} else {
db.updateAssessment(currentAssessment, courseCalled, assessmentNameStr,
assessmentTypeStr, assessmentDueStr);
allAssessments = db.getAssessments();
Toast.makeText(CourseActivity.this, "Assessment updated.",
Toast.LENGTH_SHORT).show();
this.recreate();
}
}
}
public void newAssessmentButton(View v) {
EditText assessmentName = findViewById(R.id.assessment_title);
assessmentName.setText("");
EditText assessmentType = findViewById(R.id.assessment_type);
assessmentType.setText("");
EditText assessmentDue = findViewById(R.id.assessment_due);
assessmentDue.setText("");
currentAssessment = -1;
}
public void deleteAssessmentButton(View v) {
System.out.println("start of deleteAssessmentButton, currentAssessment = " + currentAssessment);
if(currentAssessment == -1) {
System.out.println("currentAssessment = " + currentAssessment);
EditText assessmentName = findViewById(R.id.assessment_title);
assessmentName.setText("");
EditText assessmentType = findViewById(R.id.assessment_type);
assessmentType.setText("");
EditText assessmentDue = findViewById(R.id.assessment_due);
assessmentDue.setText("");
Toast.makeText(CourseActivity.this, "No assessment chosen.",
Toast.LENGTH_SHORT).show();
} else {
System.out.println("sending to delete assessment id: " + currentAssessment);
long result = db.deleteAssessment(currentAssessment);
if(result == -1) {
Toast.makeText(CourseActivity.this, "Assessment NOT deleted.",
Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(CourseActivity.this, "Assessment deleted. result = " + result,
Toast.LENGTH_SHORT).show();
allAssessments = db.getAssessments();
this.recreate();
}
}
}
public Assessment getAssessment(int id) {
Assessment assessment = new Assessment();
for(Assessment asmt : allAssessments) {
if(asmt.getId() == id) {
assessment = asmt;
}
}
return assessment;
}
}
我已经检查并重新检查了代码，在单击listView和单击Delete按钮（应重置活动）之间找不到任何位置。这是在listView onClick之后自动发生的吗？还有另一种方式来跟踪ID吗？
答案 0 :(得分：3)
您似乎有两个currentAssessment变量。一个是该类专用的，另一个是局限于onItemClick范围内的。一旦onItemClick退出，您就失去了该分配，在您引用currentAssessment的其他任何地方，它都是属于该类的那个，仍为-1。
解决方法是为currentAssessment使用类onItemClick。
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
currentAssessment = assessmentIDs[(int)id];
System.out.println("set to clicked id, currentAssessment = " + currentAssessment);
Assessment assessment = getAssessment(currentAssessment);
String assessmentNameStr = assessment.getTitle();
String assessmentTypeStr = assessment.getType();
String assessmentDueStr = assessment.getDueDate();
EditText assessmentName = findViewById(R.id.assessment_title);
assessmentName.setText(assessmentNameStr);
EditText assessmentType = findViewById(R.id.assessment_type);
assessmentType.setText(assessmentTypeStr);
EditText assessmentDue = findViewById(R.id.assessment_due);
assessmentDue.setText(assessmentDueStr);
System.out.println("end of onclickListener, currentAssessment = " + currentAssessment);
}
});