实现思路：通过自定义View在频幕右侧循环写入a~z;复写onTouchEvent
@Overridepublic boolean onTouchEvent(MotionEvent event) {switch (event.getAction()) {case MotionEvent.ACTION_MOVE:break;case MotionEvent.ACTION_DOWN:break;case MotionEvent.ACTION_UP:break;}
点击的时候获取点击的字母传给 listener.onItemSelect(index, array[index]); 使用观察者模式` //观察者模式 public interface OnItemSelect { public void onItemSelect(int index, String indexString); }
private OnItemSelect listener;public void setOnItemSelectListener(OnItemSelect listener) {this.listener = listener;}`
在MainActivity当中
mySlider.setOnItemSelectListener(new MySlider.OnItemSelect(){(int index, String indexString) {textView.setText(indexString);}});
将字母赋给textView
通过自定义View实现，代码及注释如下
自定义View{private String[] array = {“a”, “b”, “c”, “d”, “e”, “f”, “g”, “h”, “i”, “j”, “k”, “l”, “m”, “n”, “o”, “p”, “q”, “r”, “s”, “t”, “u”, “v”, “w”, “x”, “y”, “z”};private int width;private int height;private Paint paint;private Paint paintTouch;private int index = -1;{(int index, String indexString);}private OnItemSelect listener;(OnItemSelect listener) {this.listener = listener;}public MySlider(Context context, AttributeSet attrs) {super(context, attrs);paint = new Paint();paint.setTextAlign(Paint.Align.CENTER);paint.setTextSize(30);paintTouch = new Paint();paintTouch.setColor(Color.GREEN);paintTouch.setTextSize(32);}(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);width = getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec);height = getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec);setMeasuredDimension(width, height);}private float x;private float y;(MotionEvent event) {switch (event.getAction()) {case MotionEvent.ACTION_MOVE:case MotionEvent.ACTION_DOWN:x = event.getX();y = event.getY();if (x > width – paint.measureText(“m”) * 2) {index = (int) y / (height / 26);Log.d(“”, “点击的字母” + array[index]);if (listener != null) {listener.onItemSelect(index, array[index]);}invalidate();return true;}break;case MotionEvent.ACTION_UP:index = -1;invalidate();break;}return super.onTouchEvent(event);}(Canvas canvas) {super.onDraw(canvas);for (int i = 0; i < 26; i++) {if (index == i) {canvas.drawText(“” + array[i], width – paint.measureText(“m”), height / 26 * (i + 1), paintTouch);} else {canvas.drawText(“” + array[i], width – paint.measureText(“m”), height / 26 * (i + 1), paint);}}}}Activity{private MySlider mySlider;private TextView textView;(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_mainmyslider);//mySlider既是一个控件又是类名mySlider= (MySlider) findViewById(R.id.myslider);textView= (TextView) findViewById(R.id.textview);mySlider.setOnItemSelectListener(new MySlider.OnItemSelect(){(int index, String indexString) {textView.setText(indexString);}});}}XML布局==”match_parent”><com.example.administrator.canvas.widget.MySlider=”match_parent”/><TextView==>
，积极的人在每一次忧患中都看到一个机会，
