Question

我一直在寻找这个问题。几天前我开始编码，我正在尝试创建一个动态列表视图，您可以通过选中复选框并删除选中的选项来添加字符串并将其删除。

此代码有效，但只有在从上到下检查多个项目时才能删除。如果我开始检查底部，然后检查顶部，它只删除顶部的一个。如果我从下到上检查所有方框，它会移除顶部和底部。如果我先检查中间的一个而不先检查其他内容，它会正确删除它。

请提供任何帮助。

public class Main3Activity extends AppCompatActivity {

ArrayList<String> questions = new ArrayList<String>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main3);


    //listview

    //add items
    questions.add("Jag har aldrig");
    questions.add("Jag har aldrig varit");
    questions.add("Jag har aldrig2");

    //Checkboxadapters
    final ListView questionList = (ListView) findViewById(R.id.questionList);
    final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.list_item, questions);
    if(questionList != null) {
        questionList.setAdapter(adapter);
        questionList.setItemsCanFocus(false);
        questionList.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
        /*questionList.setOnItemClickListener(new AdapterView.OnItemClickListener() {  //LISTENER
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                CheckedTextView ctv = (CheckedTextView)view;
                if(ctv.isChecked()){
                    Toast.makeText(Main3Activity.this, "now it is checked", Toast.LENGTH_SHORT).show();
                }else{
                    Toast.makeText(Main3Activity.this, "now it is unchecked", Toast.LENGTH_SHORT).show();
                }
            }
        });*/
    }


    //Erasebutton listener
    final Button eraseButton = (Button) findViewById(R.id.eraseButton);
    assert eraseButton != null;
    eraseButton.setOnClickListener(new View.OnClickListener() { //erasebutton onclick
        public void onClick(View eraseButton) {
            assert questionList != null;
            SparseBooleanArray checked = questionList.getCheckedItemPositions();
            for(int i=0; i < questionList.getCount(); i++)
            {
                if(checked.get(i)) {
                    //What to do with selected listitems
                    String item = (String) questionList.getAdapter().getItem(i);
                    Toast.makeText(Main3Activity.this, String.format("Removed: %s",item), Toast.LENGTH_SHORT).show();
                    adapter.remove(questions.get(i));
                }
            }
            checked.clear();
            adapter.notifyDataSetChanged();
        }
    });



    //Nextbutton listener
    final Button returnButton = (Button) findViewById(R.id.returnButton);
    assert returnButton != null;
    returnButton.setOnClickListener(new View.OnClickListener() { //Nextbutton onclick
        public void onClick(View returnButton) {
            Intent mainMenu = new Intent(Main3Activity.this, Main2Activity.class);
            Main3Activity.this.startActivity(mainMenu);
        }
    });


}

}

Answer 1

当您删除项目时，总计数更改和其他项目已移位，因此您的循环正确删除列表视图中的第一个选中项目。您可以尝试更改循环的方向：

for(int i = questionList.getCount() - 1; i >= 0; i--)
        {
            if(checked.get(i)) {
                //What to do with selected listitems
                String item = (String) questionList.getAdapter().getItem(i);
                Toast.makeText(Main3Activity.this, String.format("Removed: %s",item), Toast.LENGTH_SHORT).show();
                adapter.remove(questions.get(i));
            }
        }

说明你的循环如何运作：

使用复选框删除按钮上的多个listview项

1 个答案: