Use Case Description（描述使用案例）

請設計一個應用程式，內有三個SeekBar，並分別代表著三原色(紅、綠、藍)，值為0～255，只要 滑動其中一個SeekBar，背景的顏色就會跟著改變，
(結束滑動時，會顯示目前滑動顏色的數值為多 少，)



方法三：

public class MainActivity extends AppCompatActivity {
    private ConstraintLayout constraintLayout;    private SeekBar sbRed, sbGreen, sbBlue;    private int Red, Green, Blue;    private SeekBar.OnSeekBarChangeListener listener1= new SeekBar.OnSeekBarChangeListener() {
        @Override        public void onProgressChanged(SeekBar seekBar, int progress, boolean b) {
            switch (seekBar.getId()){
                case R.id.redBar:
                    Red=progress;                    break;                case R.id.greenBar:
                    Green=progress;                    break;                case R.id.blueBar:
                    Blue=progress;                    break;            }
            constraintLayout.setBackgroundColor(Color.rgb(Red, Green, Blue));        }
        @Override        public void onStartTrackingTouch(SeekBar seekBar) {     }
        @Override        public void onStopTrackingTouch(SeekBar seekBar) {    }
    };
    @Override    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        changeView();    }

    private void changeView(){
        constraintLayout = (ConstraintLayout) findViewById(R.id.constraintLo);        sbRed = (SeekBar) findViewById(R.id.redBar);        sbRed.setOnSeekBarChangeListener(listener1);        sbGreen = (SeekBar) findViewById(R.id.greenBar);        sbGreen.setOnSeekBarChangeListener(listener1);        sbBlue = (SeekBar) findViewById(R.id.blueBar);        sbBlue.setOnSeekBarChangeListener(listener1);    }
}