我想删除在ArrayList列表中有副本的项目。
例如：
列表= {54,55,55} NewList = {54}
OR
列表= {54,55,55,55} NewList = {54,55}
我的代码：
public void submit(){
checked.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
int j = 0;
int k = 1;
int l =0;
int size = list.size();
String temp = "";
//removing common
while (j < size) {
while(k < size){
if(list.get(j) == list.get(k)){
list.remove(k);
}
k++;
}
j++;
}
int newsize = list.size();
//printing
while (l < newsize){
temp = temp + " " + list.get(l);
l++;
}
MessageTo.message(ViewTasksActivity.this, temp);
}
});
}
我的代码仅适用于此条件，例如：
list = {54,56,57,54}
然后点击提交以清除列表
list = {56,57} 正确
但有了这个条件
list = {54,55,57,58,55}
然后点击提交以清除列表
list = {54,55,57,58,55} INCORRECT 应删除55
或
list = {54,55,55,58,55}
然后点击提交以清除列表
list = {54,55,55,58,55} INCORRECT 应删除55但仍然只有一个55，应为{54,55,58}
------- -------更新
完整代码
public class ViewTasksActivity extends AppCompatActivity {
private GridLayout gridLayout;
private Button b,checked;
private CheckBox cb;
ArrayList<Integer> list;
public int goal_id,actid;
int rowIndex = 1;
int colIndex = 0;
int rowIndex2 = 1;
int colIndex2 = 1;
int rowIndex3 = 1;
int colIndex3 = 2;
int i=0;
MyDBAdapter dbhandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_tasks);
Bundle extras = getIntent().getExtras();
if (extras == null) {
return;
}
//layout variables
gridLayout = (GridLayout) findViewById(R.id.taskListLayout);
checked = (Button) findViewById(R.id.checktasks);
goal_id = Integer.parseInt(extras.getString("goalid"));
actid = Integer.parseInt(extras.getString("activityId"));
list = new ArrayList<Integer>();
dbhandler = new MyDBAdapter(this);
set = new HashSet<>();
displayAllTasks();
submit();
}
public void displayAllTasks(){
//get a list of all tasks
List<Tasks> allTasks = dbhandler.getAllTasksbyActivity(goal_id,actid);
for (final Tasks task : allTasks){
//task name
TextView textView2 = new TextView(ViewTasksActivity.this);
GridLayout.LayoutParams param3 = new GridLayout.LayoutParams();
param3.rowSpec = GridLayout.spec(rowIndex);
param3.columnSpec = GridLayout.spec(colIndex);
textView2.setTextColor(Color.BLACK);
textView2.setLayoutParams(param3);
textView2.setText(task.getTaskName());
//status
TextView textView = new TextView(ViewTasksActivity.this);
GridLayout.LayoutParams param = new GridLayout.LayoutParams();
param.rowSpec = GridLayout.spec(rowIndex2);
param.columnSpec = GridLayout.spec(colIndex2);
textView.setTextColor(Color.BLACK);
textView.setLayoutParams(param);
if(task.getComplete().equalsIgnoreCase("False")){
cb = new CheckBox(ViewTasksActivity.this);
GridLayout.LayoutParams param4 = new GridLayout.LayoutParams();
param4.rowSpec = GridLayout.spec(rowIndex3);
param4.columnSpec = GridLayout.spec(colIndex3);
param4.setMargins(30, 5, 5, 5);
cb.setLayoutParams(param4);
cb.setId(task.getTaskId());
cb.setClickable(Boolean.TRUE);
textView.setText(" Incomplete");
cb.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
list.add(task.getTaskId());
i++;
}
});
}
else
{
cb = new CheckBox(ViewTasksActivity.this);
GridLayout.LayoutParams param5 = new GridLayout.LayoutParams();
param5.rowSpec = GridLayout.spec(rowIndex3);
param5.columnSpec = GridLayout.spec(colIndex3);
param5.setMargins(30, 5, 5, 5);
cb.setLayoutParams(param5);
textView.setText(" Complete");
cb.setId(task.getTaskId());
cb.isChecked();
cb.setClickable(Boolean.FALSE);
}
gridLayout.addView(textView);
gridLayout.addView(textView2);
gridLayout.addView(cb);
rowIndex3++;
rowIndex2++;
rowIndex++;
}
}
public void submit(){
checked.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
int j = 0;
int k = 1;
int l =0;
int size = list.size();
String temp = "";
//removing common
while (j < size) {
while(k < size){
if(list.get(j) == list.get(k)){
list.remove(k);
}
k++;
}
j++;
}
int newsize = list.size();
//printing
while (l < newsize){
temp = temp + " " + list.get(l);
l++;
}
MessageTo.message(ViewTasksActivity.this, temp);
}
});
}
public void goBack(){
Intent myIntent = new Intent(ViewTasksActivity.this, ViewActActivity.class);
myIntent.putExtra("goalid", Integer.toString(goal_id));
startActivity(myIntent);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_view_tasks, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_back) {
goBack();
return true;
}
return super.onOptionsItemSelected(item);
}
}
答案 0 :(得分：0)
您没有重置索引＆＃39; k＆＃39;每次循环后。 所以目前它只检查第一个元素而不是其他所有元素...... 你需要添加：
while (j < size) {
// Add k = 0; here
k = 0;
while(k < size)
答案 1 :(得分：0)
如果您要删除相同值的对，以便[1, 1, 2]变为[2]，但[1, 1, 1, 2]变为[1, 2]，则可以使用这样Set：
// list contains [1, 2, 3, 4, 2, 3, 2]
Set<Integer> set = new HashSet<>();
for (Integer i : list) {
if (set.contains(i)) {
set.remove(i);
} else {
set.add(i);
}
}
list.clear();
list.addAll(set);
System.out.println(list); // [1, 2, 4]
如果您想保留订单，请改用LinkedHashSet。
答案 2 :(得分：0)
public ArrayList<int> cleanList(ArrayList<int> list){
ArrayList<int> newList = new ArrayList<int>();
for(int i = 0; i < list.size(); i++){
int item = list.get(i);
if(!newList.contains(item)){
newList.add(item);
}
}
return newList;
}
下面的几个答案建议使用我同意的Set，但如果您出于某种原因需要使用ArrayList，那么干净利落的方式就是明确的。只有一个循环遍历列表并返回一个已清理的新ArrayList。
答案 3 :(得分：0)
您可以通过再次循环 arrayList 来删除项目。但它又增加了时间复杂度。
为什么不使用集合，禁止使用重复的元素。
Set<Integer> set = new HashSet<Integer>();
set.add();
答案 4 :(得分：0)
在下面有一种删除重复值的替代方法。我在我的代码中添加了评论。
public static void main(String[] args) {
ArrayList<Integer> myList = new ArrayList<Integer>();
myList.addAll(Arrays.asList(new Integer[] { 33, 34, 34, 33 }));
System.out.println(removeDuplicateValues(myList));
}
public static ArrayList<Integer> removeDuplicateValues(ArrayList<Integer> list) {
Integer[] myList = new Integer[list.size()];
myList = list.toArray(myList); // we should copy our array at the first because we will modify the original one in the loop.
for (Integer integer : myList) {
list.remove(integer); // first remove the integer
if (!list.contains(integer))
list.add(integer); // add it again if it does not exist afer removing.
}
return list;
}
打印：[33,34]而我们的arraylist有值：[33,34,34,33]
如果要删除所有重复值：
public static void main(String[] args) {
ArrayList<Integer> myList = new ArrayList<Integer>();
myList.addAll(Arrays.asList(new Integer[] { 35, 34, 34, 33 }));
System.out.println(removeAllDublicateValues(myList));
}
public static ArrayList<Integer> removeAllDuplicateValues(ArrayList<Integer> list) {
Integer[] myList = new Integer[list.size()];
myList = list.toArray(myList); // we should copy our array at the first because we will modify the original one in the loop.
List<Integer> duplicateList = new ArrayList<Integer>();
for (Integer integer : myList) {
list.remove(integer); // first remove the integer
if (!list.contains(integer) && !duplicateList.contains(integer))
list.add(integer); // add it again if it does not exist afer removing. And it is not a diplicate value
else
duplicateList.add(integer);
}
return list;
}
打印：[35,33]而我们的arraylist有值：[35,34,34,33]