1 /* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 package com.example.hellojni; 17 18 import android.app.Activity; 19 import android.widget.TextView; 20 import android.os.Bundle; 21 22 23 public class HelloJni extends Activity 24 { 25 /** Called when the activity is first created. */ 26 @Override onCreate(Bundle savedInstanceState)27 public void onCreate(Bundle savedInstanceState) 28 { 29 super.onCreate(savedInstanceState); 30 31 /* Create a TextView and set its content. 32 * the text is retrieved by calling a native 33 * function. 34 */ 35 TextView tv = new TextView(this); 36 tv.setText( stringFromJNI() ); 37 setContentView(tv); 38 } 39 40 /* A native method that is implemented by the 41 * 'hello-jni' native library, which is packaged 42 * with this application. 43 */ stringFromJNI()44 public native String stringFromJNI(); 45 46 /* This is another native method declaration that is *not* 47 * implemented by 'hello-jni'. This is simply to show that 48 * you can declare as many native methods in your Java code 49 * as you want, their implementation is searched in the 50 * currently loaded native libraries only the first time 51 * you call them. 52 * 53 * Trying to call this function will result in a 54 * java.lang.UnsatisfiedLinkError exception ! 55 */ unimplementedStringFromJNI()56 public native String unimplementedStringFromJNI(); 57 58 /* this is used to load the 'hello-jni' library on application 59 * startup. The library has already been unpacked into 60 * /data/data/com.example.hellojni/lib/libhello-jni.so at 61 * installation time by the package manager. 62 */ 63 static { 64 System.loadLibrary("hello-jni"); 65 } 66 } 67