java - 如何使用 TextView 方法输出整数？

Question

我想在Activity中输出一个总是偶数的随机数!这是我的代码，问题出在哪里？

 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_fourth);
    OnClickButtonListener();
    textBox.setText("" + randomInt);


}
double randNumber = Math.random();
int d = (int) (randNumber * 100 );


int randomInt = (int)d * 2;

TextView textBox = (TextView) findViewById(R.id.textView8);

Answer 1

您需要在 onCreate() 方法中初始化 TextView。你的代码看起来像这样

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_fourth);
    TextView textBox = (TextView) findViewById(R.id.textView8);
    double randNumber = Math.random();
    int d = (int) (randNumber * 100 );      
    int randomInt = (int)d * 2;
    textBox.setText("" + randomInt);

}