具有渐变透明背景的Android线性布局

// 导入必要的类
import android.graphics.Color;
import android.graphics.drawable.GradientDrawable;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.LinearLayout;

public class MainActivity extends AppCompatActivity {

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

        // 获取线性布局对象
        LinearLayout linearLayout = findViewById(R.id.linear_layout);

        // 创建渐变透明背景
        GradientDrawable gradientDrawable = new GradientDrawable(
                GradientDrawable.Orientation.TOP_BOTTOM,
                new int[]{Color.TRANSPARENT, Color.parseColor("#FF0000")}
        );

        // 设置线性布局的背景为渐变透明背景
        linearLayout.setBackground(gradientDrawable);
    }
}