Android获取当前系统日期和时间

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //创建线性布局管理器
        LinearLayout layout = new LinearLayout(this);
        //显示改layout
        super.setContentView(layout);
        layout.setOrientation(LinearLayout.VERTICAL);
		//创建TextView
        final TextView show = new TextView(this);
		//创建Button
        Button bn = new Button(this);
        bn.setText(R.string.ok);
        bn.setLayoutParams(new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,
                ViewGroup.LayoutParams.MATCH_PARENT));
		//添加TextView
        layout.addView(show);
		//添加Button
        layout.addView(bn);
		//设置一个监听事件
        bn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                show.setText("hello , Android , " + new java.util.Date());
            }
        });
    }
}

	show.setText("hello , Android , " + new java.util.Date());