android - 我可以将 LayoutPrams 与 ViewGroup.addView 重用吗？

Question

ViewGroup.addView 是否将 LayoutParams 数据克隆到内部或链接到它？我可以通过多次调用不同 View 的 addView() 来重用 LayoutParams 的同一个实例吗？

apidoc中没有关于它的任何内容。

哇

答案是否定的(通过实验验证):

public class SymbolPadActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    RelativeLayout.LayoutParams labelParams;

    /*
     * This block to reuse is not working
    labelParams = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
    labelParams.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);
    labelParams.addRule(RelativeLayout.ALIGN_PARENT_TOP, RelativeLayout.TRUE);
    */


    RelativeLayout mover = new RelativeLayout(this);

    TextView textView;
    for(int leftMargin = 0; leftMargin<3000; leftMargin += 100) {
        for(int topMargin=0; topMargin<800; topMargin += 40) {

            // I can't omit these 3 lines 
            labelParams = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
            labelParams.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);
            labelParams.addRule(RelativeLayout.ALIGN_PARENT_TOP, RelativeLayout.TRUE);

            labelParams.leftMargin = leftMargin;
            labelParams.topMargin = topMargin;

            textView = new TextView(this);
            textView.setText("(" + leftMargin + "," + topMargin + ")");
            mover.addView(textView, labelParams);

        }
    }




    RelativeLayout.LayoutParams moverParams = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
    moverParams.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);
    moverParams.addRule(RelativeLayout.ALIGN_PARENT_TOP, RelativeLayout.TRUE);
    moverParams.leftMargin = 0;
    moverParams.topMargin = 0;

    RelativeLayout stator = new RelativeLayout(this);
    stator.addView(mover, 0, moverParams);

    setContentView(stator);


}

Answer 1

There is nothing about it in apidoc.

这意味着无论当前的实现是什么，您都需要做出更保守的选择，因为实现可能会发生变化。

因此，您需要假设使用不同的 Views 重用 LayoutParams 的实例是不安全的。

就其值(value)而言，据我所知，无论如何都是如此 - ViewGroup 不会复制。