Question

（！）onClick方法不存在

未找到相应的方法处理程序'public void navigate（android.view.View）'onClick属性值应该是此View的上下文中方法的名称，以便在单击视图时调用。此名称必须对应于只接受View类型的一个参数的公共方法。必须是字符串值，使用'\;'转义unicode字符的'\ n'或'\ uxxxx'等字符。

* 您好，我是新来的，我只是在Coursera上尝试课程，但似乎它已经过时了，而且有些东西不能正常运行。我一直试图在论坛上搜索找到答案，我尝试了几件事，但似乎我太迟钝了，而且是新手。这可能与我的工具有关：上下文？

继承我的xml：

<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp"
tools:context="MainActivity"
android:background="#ffffff">


<NumberPicker
    android:id="@+id/numberPicker"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="OK"
    android:id="@+id/button"
    android:layout_below="@+id/numberPicker"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:onClick="navigate"/>

<WebView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/webView"
    android:layout_below="@+id/button"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

继承我的java：

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.NumberPicker;
import android.view.View;

public class MainActivity extends AppCompatActivity {

NumberPicker possibilities;
WebView webView;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    possibilities = (NumberPicker) findViewById(R.id.numberPicker);
    webView = (WebView) findViewById(R.id.webView);
    String[] possibilitiesStrings = {
            "Android",
            "Checklist text-input fields",
            "Coursera",
            "Supelec",
    };
    possibilities.setDisplayedValues(possibilitiesStrings);
    possibilities.setMinValue(0);
    possibilities.setMaxValue(possibilitiesStrings.length - 1);

    /**
     * called when the OK button from activity_main.xml is clicked
     * @param v the View which triggered the method call: the OK button
     */
    public void navigate(View v) {
    int choice = possibilities.getValue();
        webView.setWebViewClient(new WebViewClient());
    if (choice == 0)
        webView.loadUrl("file:///android_asset/android.html");
    else if (choice == 1)
    webView.loadUrl("file:///android_asset/checklist.html");
else if (choice == 2)
    webView.loadUrl("http:///www.coursera.org");
else if (choice == 3)
    webView.loadUrl("file:///android_asset/supelec.html");
}

}


}
}

Answer 1

我分析了您的代码，并且我看到您在onCreate() method中声明了导航方法，因此您可以从xml中找到它。

如何在xml中使用声明方法

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.NumberPicker;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    NumberPicker possibilities;
    WebView webView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        possibilities = (NumberPicker) findViewById(R.id.numberPicker);
        webView = (WebView) findViewById(R.id.webView);
        String[] possibilitiesStrings = {
                "Android",
                "Checklist text-input fields",
                "Coursera",
                "Supelec",
        };
        possibilities.setDisplayedValues(possibilitiesStrings);
        possibilities.setMinValue(0);
        possibilities.setMaxValue(possibilitiesStrings.length - 1);

    }

    /**
     * called when the OK button from activity_main.xml is clicked
     * @param v the View which triggered the method call: the OK button
     */
    public void navigate(View v) {
        int choice = possibilities.getValue();
        webView.setWebViewClient(new WebViewClient());
        if (choice == 0)
            webView.loadUrl("file:///android_asset/android.html");
        else if (choice == 1)
            webView.loadUrl("file:///android_asset/checklist.html");
        else if (choice == 2)
            webView.loadUrl("http:///www.coursera.org");
        else if (choice == 3)
            webView.loadUrl("file:///android_asset/supelec.html");
    }
}

onClick方法不存在

1 个答案: