android - 以编程方式在线性布局中 ScrollView

Question

我正在尝试以编程方式使我的 linearLayout 可滚动，但它不起作用。我只是 android 的新手，所以请多多关照!..

完整代码

  ScrollView scrollView= new ScrollView(this);
                LinearLayout mainLayout= new LinearLayout(this);
                mainLayout.setOrientation(LinearLayout.VERTICAL);

                for (int i = 1; i <= 20; i++) {
                    LinearLayout linearLayout = new LinearLayout(this);
                    linearLayout.setOrientation(LinearLayout.HORIZONTAL);
                    linearLayout.setTag(i);
                    Button btn1 = new Button(this);
                    btn1.setId(i);
                    final int id_ = btn1.getId();
                    btn1.setText("button " + id_);

                   btn1 = ((Button) findViewById(id_));
                    btn1.setOnClickListener(new View.OnClickListener() {
                        public void onClick(View view) {
                            Toast.makeText(view.getContext(),
                                    "Button 1 clicked index = " + id_, Toast.LENGTH_SHORT)
                                    .show();
                        }
                    }); 
                  linearLayout.addView(btn1);
                   mainLayout.addView(linearLayout);


                }
                 scrollView.addView(mainLayout);
                    setContentView(scrollView);

错误堆栈跟踪

Answer 1

问题是 btn1 = ((Button) findViewById(id_));

这应该看起来像 btn1 = (Button) findViewById(R.id.whatever_your_id_is_in_xml);

因为你不提供 id 它永远找不到你的按钮，所以当你尝试设置监听器时 btn1 为空

(查找 View 正在 xml/ Root View 中查找此 ID，您不需要这样做 - 您已经有了按钮，因为您是通过编程方式创建的)

编辑

您的解决方案是完全删除这一行:btn1 = ((Button) findViewById(id_));