使用 android studio 4.2.1 一个 java 代码不起作用。 表明 C:\Users\NahidOnim\AndroidStudioProjects\JustJava\app\src\main\java\com\example\android\justjava\MainActivity.java:4: 错误:找不到符号 导入 android.support.v7.app.ActionBarActivity; ^ 符号:类 ActionBarActivity 位置:包 android.support.v7.app
代码如下
package com.example.android.justjava;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.TextView;
/**
* This app displays an order form to order coffee.
*/
public class MainActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
/**
* This method is called when the order button is clicked.
*/
public void submitOrder(View view) {
display(1);
}
/**
* This method displays the given quantity value on the screen.
*/
private void display(int number) {
TextView quantityTextView = (TextView) findViewById(
R.id.quantity_text_view);
quantityTextView.setText("" + number);
}
}
谁能告诉我为什么会这样??