Android Studio：如何解决此执行错误

Question

我是 android studio 的新手，我不明白为什么当我开始使用搜索栏时我的应用程序崩溃了。有人可以帮我吗？

公共类 MainActivity 扩展 AppCompatActivity { SeekBar seeBar; //声明seekbar对象TextView textView, textView2; 列表视图简单列表视图；//为SeekBar声明成员变量 int离散; int开始= 50；int 起始位置 = 50; //进度跟踪器 int temp = 0; //为ViewStub声明对象ViewStub存根; 复选框复选框；列表视图lv; //声明Listview对象Button按钮; 查看视图；

public MainActivity() {

    discrete = 0;

}

@Override

public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);

    //declare viewstub object

    stub = findViewById(R.id.viewStub1);

    @SuppressWarnings("unused")

    View inflated = stub.inflate();

    stub.setVisibility(View.INVISIBLE);

    //ViewStub logic

    checkBox = findViewById(R.id.checkBox1);

    //handle checkbox click event

    checkBox.setOnCheckedChangeListener(new CheckBox.OnCheckedChangeListener(){

        public void onCheckedChanged(CompoundButton arg0, boolean isChecked) {

            if (isChecked) {

                //remove objs from parent view to allow for child view objs

                checkBox.setVisibility(View.GONE);

                seekBar.setVisibility(View.GONE);

                textView.setVisibility(View.GONE);

                stub.setVisibility(View.VISIBLE);

            }

        }

    });

    //seekbar logic

    textView = findViewById(R.id.textview);

    textView = findViewById(R.id.textView2);

    textView.setText(" Celsius at 0 degrees");

    //set default view

    seekBar = findViewById(R.id.seekbar);

    seekBar.setProgress(start_position);

    //create event handler for SeekBar

    seekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener(){

        @Override

        public void onStopTrackingTouch(SeekBar seekBar) {

            if (temp == 0) {

                //for initial view result

                //Toast.makeText(getBaseContext(), "Fahrenheit result: 32 degrees",

                        //Toast.LENGTH_SHORT).show();

                textView2.setText("Fahrenheit result 32 degrees") ;

            }

Answer 1

TextView textView = findViewById(R.id.textview); TextView textView2 = findViewById(R.id.textView2);

Answer 2

textView = findViewById(R.id.textview); textView = findViewById(R.id.textView2);textView2 此处未初始化...将上面的代码改为textView = findViewById(R.id.textview); textView2 = findViewById(R.id.textView2);

Answer 3

初始化textView2 你似乎错过了那部分