首頁猿問為啥空指針？

為啥空指針？

Android

qq_Linjj藍(lán)極光輝_04362138 2017-11-24 10:37:18

setOnClickListener的代碼：btnComfirm.setOnClickListener(new View.OnClickListener() { ? ?@Override ? ?public void onClick(View v) { ? ? ? ?cartProvider.addData(goodsBean); ? ? ? ?window.dismiss(); ? ? ? ?Toast.makeText(GoodsInfoActivity.this, "加入購物車", Toast.LENGTH_SHORT).show(); ? ?}});btnCancel.setOnClickListener(new View.OnClickListener() { ? ?@Override ? ?public void onClick(View v) { ? ? ? ?cartProvider.addData(goodsBean); ? ? ? ?window.dismiss(); ? ? ? ?Toast.makeText(GoodsInfoActivity.this, "取消加入購物車", Toast.LENGTH_SHORT).show(); ? ?}});………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………定義變量和通過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 );………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………報錯;?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

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1 回答

ysutm

TA貢獻(xiàn)2條經(jīng)驗獲得超1個贊

檢查下
1、初始化button之前是否調(diào)了setContentView(view);

2、設(shè)置的view是否包含了你那2個button的id

反對回復(fù) 2017-11-25

qq_Linjj藍(lán)極光輝_04362138
這個會不會少了啥 class ViewHolder extends RecyclerView.ViewHolder { public Context mContext; public ViewHolder(View view) { super(view); } **************************************************************************** 在唯一的setcontentView protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_goods_info); setContentView(R.layout.popwindow_add_product); findViews();

回復(fù) 2017-11-28
qq_Linjj藍(lán)極光輝_04362138
我發(fā)現(xiàn)我setContentView兩個布局它只生效一個，另一個為空

回復(fù) 2017-11-28