Question

我正在尝试在应用中实现PayPal功能。为了让它正常工作，我正在尝试创建一个只显示PayPal按钮的简单应用程序，按下该按钮后，会将所有必要参数传递给库，以便用户完成登录和付款流程。

当我运行此代码时，收到以下错误消息：

03-11 20：48：05.588 23566-23566 / org.kevinbright.android.paypaldemo E / AndroidRuntime：FATAL EXCEPTION：main 过程：org.kevinbright.android.paypaldemo，PID：23566 java.lang.RuntimeException：无法启动活动ComponentInfo {org.kevinbright.android.paypaldemo / org.kevinbright.android.paypaldemo.MainActivity}：java.lang.NullPointerException：尝试调用虚方法'void android.widget.RelativeLayout。 addView（android.view.View）'在空对象引用
上

错误与本节有关：

((RelativeLayout) findViewById(R.id.RelativeLayout01)).
            addView(launchPayPalButton);

以下是代码：

 package org.kevinbright.android.paypaldemo;

public class MainActivity extends Activity   {

    private CheckoutButton launchPayPalButton;
    final static public int PAYPAL_BUTTON_ID = 10001;
    private static final int REQUEST_PAYPAL_CHECKOUT = 2;
    private double _theSubtotal;
    private double _taxAmount;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        initLibrary();
        showPayPalButton();

    }

    private void showPayPalButton() {
        //LinearLayout linearLayout = new LinearLayout(this);
        //linearLayout.setOrientation(LinearLayout.VERTICAL);

        //ViewGroup.LayoutParams linearLayoutParam = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);

        //setContentView(linearLayout, linearLayoutParam);

        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
        params.bottomMargin = 10;

        // Generate the PayPal checkout button and save it for later use
        PayPal pp = PayPal.getInstance();
        launchPayPalButton = pp.getCheckoutButton(this, PayPal.BUTTON_194x37, CheckoutButton.TEXT_PAY);

        // The OnClick listener for the checkout button
        launchPayPalButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                payPalButtonClick(arg0);
            }
        });

        // Add the listener to the layout
        launchPayPalButton.setLayoutParams(params);
        launchPayPalButton.setId(PAYPAL_BUTTON_ID);
        ((RelativeLayout) findViewById(R.id.RelativeLayout01)).
                addView(launchPayPalButton);

    }

    public void payPalButtonClick(View arg0) {
        PayPalPayment newPayment = new PayPalPayment();
        newPayment.setSubtotal(new BigDecimal(_theSubtotal));
        newPayment.setCurrencyType("USD");
        newPayment.setRecipient("my@email.com");
        newPayment.setMerchantName("My Company");
        Intent checkoutIntent = PayPal.getInstance().checkout(newPayment, this);
        startActivityForResult(checkoutIntent, REQUEST_PAYPAL_CHECKOUT);


    }



    public void initLibrary() {
        PayPal pp = PayPal.getInstance();

        if (pp == null) {  // Test to see if the library is already initialized

            // This main initialization call takes your Context, AppID, and target server
            pp = PayPal.initWithAppID(this, "APP-80W284485P519543T", PayPal.ENV_NONE);

            // Required settings:

            // Set the language for the library
            pp.setLanguage("en_US");

            // Some Optional settings:

            // Sets who pays any transaction fees. Possible values are:
            // FEEPAYER_SENDER, FEEPAYER_PRIMARYRECEIVER, FEEPAYER_EACHRECEIVER, and FEEPAYER_SECONDARYONLY
            pp.setFeesPayer(PayPal.FEEPAYER_EACHRECEIVER);

            // true = transaction requires shipping
            pp.setShippingEnabled(false);
        }

    }

}

我不明白为什么我收到此错误消息，因为launchPayPalButton引用了pp，PayPal Class是在initLibrary中初始化的showPayPalButton的对象调用<?xml version="1.0" encoding="utf-8"?> <RelativeLayout android:id="@+id/RelativeLayout01" android:layout_width="fill_parent" android:layout_height="fill_parent" xmlns:android="http://schemas.android.com/apk/res/android" > </RelativeLayout>之前的方法。

请帮助!!!

编辑：这与引用的问题不重复。我已经查看了该帖子，该帖子是关于引用尚未初始化的对象，因此返回空引用。这个问题解释了为什么这不应该生成空指针异常，因为该对象已初始化。

编辑2：这是名为“customize.xml”的.xml文件，保存在“Res。”下的Layouts文件夹中。

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NullPointerException：尝试在空对象引用上调用虚方法'void android.widget.RelativeLayout.addView（android.view.View）'

0 个答案: