Android之 ImageView中setId()的作用

標籤：android

 通過代碼產生ImageView,並把它添加到布局中來時，可能會遇到setId()方法，那麼它有什麼作用？

作用如下：

通過代碼添加ImageView、TextView等控制項時，有時候會用到RelativeLayout.LayoutParams等布局的addRule()方法，如下代碼：

ImageView imageView = new ImageView(this.getActivity());imageView.setId(View.generateViewId());...params.addRule(RelativeLayout.BELOW, imageView.getId());

此時就能知道setId()的作用了。就是在某控制項的下方、上方等用到具體View的地方，需要getId().

另附上一塊完整的代碼，但是沒setId()，ImageView沒有ID，直接取會造成錯誤。

 

RelativeLayout layout = new RelativeLayout(this.getActivity());    layout.setLayoutParams(new RelativeLayout.LayoutParams(             LayoutParams.FILL_PARENT,             LayoutParams.FILL_PARENT));    layout.setBackgroundColor(Color.parseColor("#CCCDCDCD"));    ImageView imageView = new ImageView(this.getActivity());    RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);    params.addRule(RelativeLayout.CENTER_IN_PARENT);    imageView.setLayoutParams(params);    imageView.setBackgroundResource(R.drawable.create_template);    AnimationDrawable frameAnimation = (AnimationDrawable) imageView.getBackground();    if (frameAnimation != null) {        frameAnimation.start();    }    TextView textView = new TextView(this.getActivity());    params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);    params.addRule(RelativeLayout.BELOW, imageView.getId());    textView.setLayoutParams(params);    textView.setText("Generating information...");    layout.addView(imageView);    layout.addView(textView);    return layout;

Android之 ImageView中setId()的作用