android – 使用单个按钮宽度以编程方式填充父级

public class test_GIFDisplay extends Activity implements View.onClickListener {

    SurfaceView sview;
    GifRun gr = new GifRun();
    Button btnBACk;

    protected void onCreate(Bundle savedInstanceStatE) {
        super.onCreate(savedInstanceStatE);
        sview = new SurfaceView(this);
        sview.setZOrderOnTop@R_616_6334@;

        gr.LoadGiff(sview,this,R.drawable.smiley);

        LinearLayout linearLayout1 = new LinearLayout(this);
        linearLayout1.setOrientation(LinearLayout.VERTICAL);
        linearLayout1.setBACkgroundColor(Color.parseColor("#27ae60"));
        linearLayout1.setLayoutParams(new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,ViewGroup.LayoutParams.WRAP_CONTENT));

        LinearLayout linearLayout2 = new LinearLayout(this);
        linearLayout2.setOrientation(LinearLayout.VERTICAL);
        linearLayout2.setBACkgroundColor(Color.parseColor("#27ae60"));
        linearLayout2.setLayoutParams(new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,ViewGroup.LayoutParams.WRAP_CONTENT));

        LinearLayout.LayoutParams p = new   
        LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT,LinearLayout.LayoutParams.WRAP_CONTENT);
        p.weight = 1.0f;

        btnBACk = new Button (this);
        btnBACk.setText("BACk");
        btnBACk.setBACkgroundColor(Color.parseColor("#f1c40f"));
        btnBACk.setGravity(Gravity.CENTER_HORIZONTAL);
        btnBACk.setLayoutParams(p);
        btnBACk.setOnClickListener(this);

        linearLayout2.addView(btnBACk);
        linearLayout1.addView(linearLayout2);
        linearLayout1.addView(sview);

        setContentView(linearLayout1);
    }

    @Override
    public void onClick(View view) {
        btnBACk = (Button) view;
        btnBACk.setBACkgroundColor(Color.parseColor("#2980b9")); //color change
        new CountDownTimer(100,50) {

            @Override
            public void onTick(long arg0) {
                // TODO Auto-generated method stub
            }

            @Override
            public void onFinish() {
                btnBACk.setBACkgroundColor(Color.parseColor("#f1c40f")); // original color
            }
        }.start();//end color changed

        finish();
    }
}