为啥空指针？

Question

setOnClickListener的代码：btnComfirm.setOnClickListener(new View.OnClickListener() {    @Override    public void onClick(View v) {        cartProvider.addData(goodsBean);        window.dismiss();        Toast.makeText(GoodsInfoActivity.this, "加入购物车", Toast.LENGTH_SHORT).show();    }});btnCancel.setOnClickListener(new View.OnClickListener() {    @Override    public void onClick(View v) {        cartProvider.addData(goodsBean);        window.dismiss();        Toast.makeText(GoodsInfoActivity.this, "取消加入购物车", Toast.LENGTH_SHORT).show();    }});………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………定义变量和通过findViewById找到控件：private Button btnCancel;private Button btnComfirm;btnCancel = (Button)findViewById( R.id.btn_cancel );btnComfirm = (Button)findViewById( R.id.btn_comfirm );tvPopPrice =(TextView)findViewById(R.id.tv_pop_price);btnCancel.setOnClickListener( this );btnComfirm.setOnClickListener( this );………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………报错; Process: com.weather.com.welcomeactivity, PID:   java.lang.RuntimeException: Unable to start activity ComponentInfo{com.weather.com.welcomeactivity/com.weather.com.welcomeactivity.app.GoodsInfoActivity}: java.lang.NullPointerException: Attempt to invoke virtual  method 'void android .widget. Button. setOnClickListener (android.view.View$OnClickListener)' on a null object reference

Answer 1

检查下
1、初始化button之前是否调了setContentView(view);

2、设置的view是否包含了你那2个button的id