MainActivity.java

package p.testwebviewcommunicate;

import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.webkit.JavascriptInterface;
import android.webkit.WebView;
import android.widget.Button;
import android.widget.Toast;


public class MainActivity extends AppCompatActivity {
    WebView webView1, webView2;

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

        webView1 = (WebView) findViewById(R.id.webView1);
        webView1.getSettings().setJavaScriptEnabled(true);
        webView1.addJavascriptInterface(new WebAppInterface1(this), "android");
        webView1.loadUrl("file:///android_asset/page1.html");

        webView2 = (WebView) findViewById(R.id.webView2);
        webView2.getSettings().setJavaScriptEnabled(true);
        webView2.loadUrl("file:///android_asset/page2.html");

        Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                webView2.loadUrl("javascript:f()");
            }
        });
    }


    private class WebAppInterface1 {
        Context context;

        WebAppInterface1(Context c) {
            context = c;
        }

        @JavascriptInterface
        public void buttonPressed() {
            Toast.makeText(context, "buttonPressed", Toast.LENGTH_LONG).show();
            webView2.loadUrl("javascript:f()");
        }
    }
}