ConstraintLayout 'setBackgroundColor()' 不起作用

问题描述

    StringBuilder ret= new StringBuilder("");
    try {
        InputStream inputStream = 
        getApplicationContext().openFileInput("chocolategumballmaker.txt");

        if ( inputStream != null ) {
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String receiveString = "";
            StringBuilder stringBuilder = new StringBuilder();

            while ( (receiveString = bufferedReader.readLine()) != null ) {
                stringBuilder.append("\n").append(receiveString);
            }

            inputStream.close();
            ret.append(stringBuilder.toString());
        }
    }
    catch (FileNotFoundException e) {
        Toast.makeText(getApplicationContext(),"File not found: " + e.toString(),Toast.LENGTH_LONG).show();
    } catch (IOException e) {
        Toast.makeText(getApplicationContext(),"Can not read file: " +            e.toString(),Toast.LENGTH_LONG).show();
    }

    while ( ret.toString().startsWith(" ") || ret.toString().startsWith("\n")){
        ret.insert(0,"\b");
    }
    if(ret.toString().trim().equals("red")){
        cl.setBackgroundColor(android.R.color.holo_red_dark);
    }
    if(ret.toString().trim().equals("pink")){
        cl.setBackgroundColor(android.R.color.holo_red_light);
    }
    if(ret.toString().trim().equals("blue")){
        cl.setBackgroundColor(android.R.color.holo_blue_dark);
    }

如果我运行此代码，背景保持白色。我尝试了更多，如下所示：

i) cl.setBackgroundColor(0xFFFFFF);

ii) cl.setBackgroundColor(Color.parseColor("RED"));

iii) cl.setBackgroundColor(Color.parseColor("#E7EECC"));

解决方法

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setbackground setbackground