Question

提前致谢，这是我的问题。我有一个数据库，每当＆＃34; SHOW DATA＆＃34;单击按钮（在相同的活动（布局）上）。因此，当用户再次单击该按钮时，我想删除布局中的视图，以便数据库的内容不会显示两次。我已经使用了removeAllView（）和removeAllViewsInLayout（），但它似乎无法正常工作（我确实没有正确使用此方法）。

这是java代码：

public void onClickShowData(){

    LinearLayout ll = (LinearLayout) findViewById(R.id.cardViewContainer);

    ll.removeAllViews();


    showAll.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Cursor cursor = myDB.getAllData();

                    if (cursor.getCount() == 0) {
                        //Toast.makeText(MainActivity.this, "There is no data", Toast.LENGTH_SHORT).show();
                        showData("Error", "Nothing found");
                        return;
                    }


                    StringBuffer tmp = new StringBuffer();

                    LinearLayout ll = (LinearLayout)findViewById(R.id.cardViewContainer);
                    Context context = getApplicationContext();

                    LinearLayout ll2 = new LinearLayout(context);
                    ll2.setOrientation(LinearLayout.VERTICAL);
                    ll2.setLayoutParams(new ActionBar.LayoutParams(
                            ViewGroup.LayoutParams.MATCH_PARENT,
                            ViewGroup.LayoutParams.MATCH_PARENT));

                    TextView tv = new TextView(context);

                    CardView cv = new CardView(context);

                    cv.setId(R.id.cardView);

                    while (cursor.moveToNext()){
                        tmp.append("name : " + cursor.getString(0) + "\n" +
                                "calory : " + cursor.getString(1) + "\n" +
                                "protein : " + cursor.getString(2) + "\n" +
                                "lipid : " + cursor.getString(3) + "\n" +
                                "clucid: " + cursor.getString(4));
                        ll.addView(cv);
                        cv.addView(ll2);
                        tv.setText(tmp.toString());
                        ll2.addView(tv);
                    }




                }
            }
    );
}

这是布局：

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_database"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="gafood.mobiledeviceproject.arianchitgar.foodmakerwithga.databaseActivity">


    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:id="@+id/scrollViewLL">

            <EditText
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:inputType="textPersonName"
                android:ems="10"
                android:layout_alignParentTop="true"
                android:layout_centerHorizontal="true"
                android:id="@+id/Name"
                android:hint="Food name"/>

            <EditText
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:inputType="numberDecimal"
                android:ems="10"
                android:layout_below="@+id/Name"
                android:layout_centerHorizontal="true"
                android:id="@+id/Calory"
                android:hint="Calory"/>

            <EditText
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:inputType="numberDecimal"
                android:ems="10"
                android:layout_below="@+id/Calory"
                android:layout_alignRight="@+id/Calory"
                android:layout_alignEnd="@+id/Calory"
                android:id="@+id/protein"
                android:hint="Protein" />

            <EditText
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:inputType="numberDecimal"
                android:ems="10"
                android:layout_below="@+id/protein"
                android:layout_centerHorizontal="true"
                android:id="@+id/lipid"
                android:hint="Lipid" />

            <Button
                android:text="Add food"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/lipid"
                android:layout_alignParentLeft="true"
                android:layout_alignParentStart="true"
                android:layout_marginTop="22dp"
                android:id="@+id/addFood" />

            <Button
                android:text="Update"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_alignBottom="@+id/addFood"
                android:layout_centerHorizontal="true"
                android:id="@+id/updateFood" />

            <Button
                android:text="Delete"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_alignTop="@+id/updateFood"
                android:layout_alignParentRight="true"
                android:layout_alignParentEnd="true"
                android:id="@+id/delete" />

            <Button
                android:text="Food DB"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/addFood"
                android:layout_alignParentLeft="true"
                android:layout_alignParentStart="true"
                android:id="@+id/showAll" />

            <Button
                android:text="search"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/updateFood"
                android:layout_alignLeft="@+id/updateFood"
                android:layout_alignStart="@+id/updateFood"
                android:id="@+id/search" />

            <Button
                android:text="Advanced"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/delete"
                android:layout_alignLeft="@+id/delete"
                android:layout_alignStart="@+id/delete"
                android:id="@+id/advancedSearch" />

            <LinearLayout
                android:orientation="vertical"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:id="@+id/cardViewContainer"></LinearLayout>


        </LinearLayout>
    </ScrollView>


</RelativeLayout>


enter code here

When the app starts When i click 3 times on show DB

Answer 1

你必须删除

LinearLayout ll = (LinearLayout) findViewById(R.id.cardViewContainer);

此行来自onClickShowData（）方法，并添加

LinearLayout ll;

到活动课程的顶部。然后在onCreate（Bundle savedInstanceState）方法中添加，

ll = (LinearLayout) findViewById(R.id.cardViewContainer);

在当前代码中，您将向ll添加视图并在另一个对象中调用ll.removeAllViews（）。

最终代码应该是类似的，

public class YourActivityName extends Activity {
LinearLayout ll;
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ll = (LinearLayout) findViewById(R.id.cardViewContainer);
        // .... other code //
}

public void onClickShowData(){
    ll.removeAllViews();
    showAll.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Cursor cursor = myDB.getAllData();

                    if (cursor.getCount() == 0) {
                        //Toast.makeText(MainActivity.this, "There is no data", Toast.LENGTH_SHORT).show();
                        showData("Error", "Nothing found");
                        return;
                    }


                    StringBuffer tmp = new StringBuffer();


                    Context context = getApplicationContext();

                    LinearLayout ll2 = new LinearLayout(context);
                    ll2.setOrientation(LinearLayout.VERTICAL);
                    ll2.setLayoutParams(new ActionBar.LayoutParams(
                            ViewGroup.LayoutParams.MATCH_PARENT,
                            ViewGroup.LayoutParams.MATCH_PARENT));

                    TextView tv = new TextView(context);

                    CardView cv = new CardView(context);

                    cv.setId(R.id.cardView);

                    while (cursor.moveToNext()){
                        tmp.append("name : " + cursor.getString(0) + "\n" +
                                "calory : " + cursor.getString(1) + "\n" +
                                "protein : " + cursor.getString(2) + "\n" +
                                "lipid : " + cursor.getString(3) + "\n" +
                                "clucid: " + cursor.getString(4));
                        ll.addView(cv);
                        cv.addView(ll2);
                        tv.setText(tmp.toString());
                        ll2.addView(tv);
                    }

                }
            }
    );
}
}

Answer 2

您正在使用onClick()设置showAll.setOnClickListener侦听器，但执行的代码不包括ll.removeAllViews()。将单击侦听器更改为以下内容，以便在单击按钮时删除视图。

showAll.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
    LinearLayout ll = (LinearLayout) findViewById(R.id.cardViewContainer);
    ll.removeAllViews();

...etc.

removeAllView（）和removeAllViewsInLayout（）没有删除

2 个答案: