代码实现自定义一个View

1、MainActivity

package com.njupt.shudu;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		
//		setContentView(R.layout.activity_main);
		setContentView(new MyView(this));
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}

2、MyView

package com.njupt.shudu;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;

public class MyView extends View{

	public MyView(Context context) {
		super(context);
		
	}
	
	@Override
	protected void onDraw(Canvas canvas) {
		Paint paint = new Paint();
		paint.setColor(Color.BLUE);
		
		canvas.drawLine(0, 0, 200, 200, paint);
		super.onDraw(canvas);
	}
}

图形编程的基本概念即自定义view的实现方法