Android oncreate函数中布局的宽度为0

在oncreate函数中布局的宽度，我需要这个尺寸，但您的valor为0。下面是我的一些代码：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main); 

    LinearLayout layout_principal=(LinearLayout)findViewById(R.id.pru);

    int mywidth=layout_principal.getWidth();
    LinearLayout.LayoutParams txt_sep_principal_Params=new LinearLayout.LayoutParams(
            LinearLayout.LayoutParams.MATCH_PARENT,
            mywidth/2);
         TextView txt_sep_principal=new TextView(this);
         txt_sep_principal.setLayoutParams(txt_sep_principal_Params);
         txt_sep_principal.setText("text of my code");
         TextView txt_sep_principal2=new TextView(this);
         txt_sep_principal2.setLayoutParams(txt_sep_principal_Params);
         txt_sep_principal2.setText("Text of my code");
    layout_principal.addView(txt_sep_principal);
    layout_principal.addView(txt_sep_principal2);


}

在这条线之后

 LinearLayout layout_principal=(LinearLayout)findViewById(R.id.pru);

尝试添加这些代码行

layout_principal.setOrientation(LinearLayout.VERTICAL);
layout_principal.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));

---

布局

可能尚未完全完成绘图。尝试在其上发布一个

runnable

。差不多

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main); 

    LinearLayout layout_principal=(LinearLayout)findViewById(R.id.pru);
    layout_principal.post(new Runnable()
    {       
      public void run()
      {
       int mywidth=layout_principal.getWidth();
       LinearLayout.LayoutParams txt_sep_principal_Params=new LinearLayout.LayoutParams(
       LinearLayout.LayoutParams.MATCH_PARENT,
       mywidth/2);
       TextView txt_sep_principal=new TextView(this);
       ...
    }
 });

编辑

public class YourActivty extends Activity
{
     // These are declarations
     TextView tv;
     Button btn;

     protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // these are initializations
        tv = (TextView) findViewById(R.id.someId);
        btn = (Button) findViewById(R.id.someOtherId);

---

请参阅我的代码中的注释以这种方式声明它们，使它们可用于整个

活动。在调用
setContentView（）
之前不能初始化它们，当然也不能在方法之外。显然，您需要将我使用的示例
视图
替换为您自己的视图。
在oncreate方法中获取版面大小还为时过早

请尝试以下代码：

@Override
 public void onWindowFocusChanged(boolean hasFocus) {
 // TODO Auto-generated method stub
 super.onWindowFocusChanged(hasFocus);
 //Here you can get the size!
   Toast.makeText(this,""+ Layout.getHeight(), Toast.LENGTH_LONG).show();
}

请在此处查看完整代码：

LinearLayout layout_principal;
    int mywidth;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); 

        layout_principal =(LinearLayout)findViewById(R.id.pru);


        LinearLayout.LayoutParams txt_sep_principal_Params=new LinearLayout.LayoutParams(
                LinearLayout.LayoutParams.MATCH_PARENT,
                mywidth/2);
             TextView txt_sep_principal=new TextView(this);
             txt_sep_principal.setLayoutParams(txt_sep_principal_Params);
             txt_sep_principal.setText("text of my code");
             TextView txt_sep_principal2=new TextView(this);
             txt_sep_principal2.setLayoutParams(txt_sep_principal_Params);
             txt_sep_principal2.setText("Text of my code");
        layout_principal.addView(txt_sep_principal);
        layout_principal.addView(txt_sep_principal2);
        }


     @Override
     public void onWindowFocusChanged(boolean hasFocus) {
     // TODO Auto-generated method stub
       super.onWindowFocusChanged(hasFocus);
      //Here you can get the size!
       mywidth=layout_principal.getWidth();
      }

请写出函数的完整标题。你在说什么？我想匿名声明混淆了他的这一行“layout\u principal.post（new Runnable（）”，这就完成了？如果你在itits override方法下面包含了这些行，就把它作为你的类放在onCreate方法之后，我放在“layout\u principal LinearLayout=（LinearLayout）findViewById（R.id.pru）“？在onWindowFocusChanged（）中无法识别我您将把它作为代码中的字段，查看edit answer AlsoSurry，应用程序运行，但宽度无法识别我，我得到0。