Question

我正在创建一个小应用，您可以通过按钮点击添加或删除表格行。每当我单击“添加行”按钮时，该按钮会向布局添加一个表行并执行它应该执行的操作。但是，“删除行”不会删除新添加的表行，但它会像它应该的那样减少（int count）。我现在已经工作和搜索了大约4到5个小时，我没有运气。这是代码：

int count = 0;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);       
    setContentView(R.layout.activity_main);
    Button buttonAdd = (Button) findViewById(R.id.button1);
    Button buttonDel = (Button) findViewById(R.id.button2);
    buttonAdd.setOnClickListener(this);
    buttonDel.setOnClickListener(this);
}



public void onClick(View v) {
    TableLayout tableLayout1;
    EditText editText1;
    EditText editText2;
    TableRow tempRow;
    EditText tempText1;
    EditText tempText2;
    TableRow tableRow1;

    tableLayout1 = (TableLayout) findViewById(R.id.tableLayout1);
    editText1 = (EditText) findViewById(R.id.editText1);
    editText2 = (EditText) findViewById(R.id.editText2);
    tempRow = new TableRow(MainActivity.this);
    tempText1 = new EditText(MainActivity.this);
    tempText2 = new EditText(MainActivity.this);
    tempText1.setInputType(InputType.TYPE_CLASS_TEXT);
    tempText2.setInputType(InputType.TYPE_NUMBER_FLAG_DECIMAL);
    tableRow1 = (TableRow) findViewById(R.id.tableRow1);

    tempRow.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));
    tempText1.setLayoutParams(editText1.getLayoutParams());
    tempText2.setLayoutParams(editText2.getLayoutParams());
    switch(v.getId()){
    case R.id.button1:
        if(count != 9){
            count++;

            tempRow.addView(tempText1);
            tempRow.addView(tempText2);
            tableLayout1.addView(tempRow);
        } else {
            final AlertDialog alertDialog = new AlertDialog.Builder(MainActivity.this).create(); //Read Update
            alertDialog.setTitle("Error");
            alertDialog.setMessage("You can only have 10 rows!");

            alertDialog.setButton("Ok", new DialogInterface.OnClickListener() {
               public void onClick(DialogInterface dialog, int which) {
                  alertDialog.dismiss();
               }
            });

            alertDialog.show();
        }
        break;
    case R.id.button2:
        if(count != 0){
            count--;
            tempRow.removeView(tempText1);
            tempRow.removeView(tempText2);
            tableLayout1.removeView(tempRow);
            //tableLayout1.invalidate();

        } else {
            final AlertDialog alertDialog = new AlertDialog.Builder(MainActivity.this).create(); //Read Update
            alertDialog.setTitle("Error");
            alertDialog.setMessage("You must have at least one row!");

            alertDialog.setButton("Ok", new DialogInterface.OnClickListener() {
               public void onClick(DialogInterface dialog, int which) {
                  alertDialog.dismiss();
               }
            });

            alertDialog.show();
        }
        break;
        default:
            //Do something;
    }

}

10-30 21:22:23.379: E/AndroidRuntime(3970): FATAL EXCEPTION: main
10-30 21:22:23.379: E/AndroidRuntime(3970): java.lang.NullPointerException
10-30 21:22:23.379: E/AndroidRuntime(3970): at com.android.hopegpacalc.MainActivity.onClick(MainActivity.java:57)
10-30 21:22:23.379: E/AndroidRuntime(3970): at android.view.View.performClick(View.java:3511)
10-30 21:22:23.379: E/AndroidRuntime(3970): at android.view.View$PerformClick.run(View.java:14105)
10-30 21:22:23.379: E/AndroidRuntime(3970): at android.os.Handler.handleCallback(Handler.java:605)
10-30 21:22:23.379: E/AndroidRuntime(3970): at android.os.Handler.dispatchMessage(Handler.java:92)
10-30 21:22:23.379: E/AndroidRuntime(3970): at android.os.Looper.loop(Looper.java:137)
10-30 21:22:23.379: E/AndroidRuntime(3970): at android.app.ActivityThread.main(ActivityThread.java:4424)
10-30 21:22:23.379: E/AndroidRuntime(3970): at java.lang.reflect.Method.invokeNative(Native Method)
10-30 21:22:23.379: E/AndroidRuntime(3970): at java.lang.reflect.Method.invoke(Method.java:511)
10-30 21:22:23.379: E/AndroidRuntime(3970): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
10-30 21:22:23.379: E/AndroidRuntime(3970): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
10-30 21:22:23.379: E/AndroidRuntime(3970): at dalvik.system.NativeStart.main(Native Method)

Answer 1

这是一个组织问题，试试这个：

public void onClick(View v) {
    // These should be class variables, like count, you don't need to re-find it on every click
    TableLayout tableLayout1 = (TableLayout) findViewById(R.id.tableLayout1);
    EditText editText1 = (EditText) findViewById(R.id.editText1);
    EditText editText2 = (EditText) findViewById(R.id.editText2);

    switch(v.getId()){
    case R.id.button1:
        if(count != 9){
            count++;

            // Create the row only when the add button is clicked
            TableRow tempRow = new TableRow(MainActivity.this);
            EditText tempText1 = new EditText(MainActivity.this);
            EditText tempText2 = new EditText(MainActivity.this);
            tempText1.setInputType(InputType.TYPE_CLASS_TEXT);
            tempText2.setInputType(InputType.TYPE_NUMBER_FLAG_DECIMAL);

            tempRow.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));
            tempText1.setLayoutParams(editText1.getLayoutParams());
            tempText2.setLayoutParams(editText2.getLayoutParams());

            tempRow.addView(tempText1);
            tempRow.addView(tempText2);
            tableLayout1.addView(tempRow);
        } else {
            // Consider using Activity's showDialog() method, to reuse this "error" dialog rather than create a new one every time
            final AlertDialog alertDialog = new AlertDialog.Builder(MainActivity.this).create(); //Read Update
            alertDialog.setTitle("Error");
            alertDialog.setMessage("You can only have 10 rows!");

            alertDialog.setButton("Ok", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    alertDialog.dismiss();
                }
            });

            alertDialog.show();
        }
        break;
    case R.id.button2:
        if(count != 0){
            // Remove the last row at count or use "tableLayout1.getChildCount() - 1"
            tableLayout1.removeView(tableLayout1.getChildAt(count));
            count--;
        } else {
            // Consider reusing the other "error" Dialog and simply changing the message
            final AlertDialog alertDialog = new AlertDialog.Builder(MainActivity.this).create(); //Read Update
            alertDialog.setTitle("Error");
            alertDialog.setMessage("You must have at least one row!");

            alertDialog.setButton("Ok", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    alertDialog.dismiss();
                }
            });

            alertDialog.show();
        }
        break;
    default:
        //Do something;
    }
}

Answer 2

每次执行onClick时，您的代码都会生成一个新的TableRow。您只应在要添加行时执行此操作。如果要删除一个，则必须使用findViewById( id )在现有视图中找到要删除的行，然后在该对象上运行removeView。

case R.id.button2:
    if ( count != 0 ) {
        count--;
        tempRow = (TableRow)findViewById( idoftablerowtodelete );
        tableLayout1.removeView( tempRow );

这意味着您必须在创建每个表格行时使用setId设置ID，并跟踪它。

Answer 3

您的删除代码是“删除”实际上不在表中的临时视图（例如tempText1） - 它们是在onClick方法内动态制作的。在进入onClick时，不要在实例化所有这些对象时，而是在每个switch语句的主体中执行此操作。对于添加按钮，只需复制和粘贴即可。对于删除一个，将对象设置为等于要删除的行。

您似乎没有办法选择要删除的行，但假设您在其他地方执行此操作，则可以使用TableLayout.removeViewAt(int index)来选择哪一行。如果您拥有视图本身而不是索引，那么还有TableLayout.removeView(View view)。

无法从布局中删除视图

3 个答案: