guide/platform/j8-jack.jd

page.title=Tnh nng ca Ngn ng Java 8
page.keywords="android N", "Java 8", "Jack"
@jd:body

<div id="qv-wrapper">
  <div id="qv">
    <ol>
      <li>
        <a href="#supported-features">Cc tnh nng v API ca Ngn ng Java 8 c h tr</a>
      </li>
      <li>
        <a href="#configuration">Kch hot cc tnh nng ca Java 8 v Jack Toolchain</a>
      </li>
    </ol>
  </div>
</div>

<p>Android N cung cp h tr cho cc tnh nng ca ngn ng Java 8
   m bn c th s dng khi pht trin cc ng dng nhm mc tiu Android N.
  Trang ny m t cc tnh nng ngn ng mi c h tr trong Bn xem trc
  Android N, cch thit lp d n ng  s dng chng v cc vn
   bit m bn c th gp phi.
</p>

<p> bt u s dng cc tnh nng ny, bn cn ti xung v ci t Android
Studio 2.1 (bn xem trc) v SDK ca Bn xem trc Android N gm c Jack toolchain
cn thit v B tr Android c cp nht cho Gradle. Nu bn cha
ci t SDK Bn xem trc Android N, hy xem <a href="{@docRoot}preview/setup-sdk.html">Thit lp  Pht trin dnh cho Android N</a>.</p>


<p class="note">
  <strong>Lu :</strong> S dng cc tnh nng mi ca ngn ng Java 8 khng phi l mt
  yu cu  pht trin cc ng dng nhm mc tiu nn tng Android N. Nu bn
   khng mun vit m vi cc tnh nng ca ngn ng Java 8 th bn c t cc gi tr
  m ngun v tng thch mc tiu thnh Java 7. Tuy nhin, bn vn
  phi bin dch vi JDK 8  dng cho nn tng Android N.
</p>

<h2 id="supported-features">
  Cc tnh nng v API ca Ngn ng Java 8 c h tr
</h2>

<p>
  Hin thi, Android khng h tr tt c cc tnh nng ca ngn ng Java 8. Tuy nhin,
  cc tnh nng sau s s dng c khi pht trin ng dng nhm mc tiu
  Bn xem trc Android N:
</p>

<ul>
  <li>
    <a class="external-link" href="https://docs.oracle.com/javase/tutorial/java/IandI/defaultmethods.html">Cc
   phng thc giao din mc nh v tnh</a>
  </li>

  <li>
    <a class="external-link" href="https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html">
    Biu thc Lambda</a>
  </li>

  <li>
    <a class="external-link" href="https://docs.oracle.com/javase/tutorial/java/annotations/repeating.html">Ch gii
    lp li</a>
  </li>
</ul>


<p>
  Ngoi ra, cc API tnh nng ca ngn ng Java 8 cng c h tr:
</p>

<ul>
  <li>Cc API phn chiu v lin quan n ngn ng:
  </li>

  <li style="list-style: none; display: inline">
    <ul>
      <li>{@code java.lang.FunctionalInterface}
      </li>

      <li>{@code java.lang.annotation.Repeatable}
      </li>

      <li>{@code java.lang.reflect.Method.isDefault()}
      </li>

      <li>v cc API Phn chiu lin quan ti cc ch gii lp li, nh
{@code AnnotatedElement.getAnnotationsByType(Class)}
      </li>
    </ul>
  </li>
  <li>Cc API tin ch:
  </li>

  <li style="list-style: none; display: inline">
    <ul>
      <li>{@code java.util.function}
      </li>
    </ul>
  </li>
</ul>

<p class="note">
  <strong>Lu :</strong> Android N k tha vic trin khai cc
   biu thc lambda trn cc lp n danh. Phng php ny cho php chng
  tng thch ngc v c th chy trn cc phin bn Android c hn.  kim th
  cc biu thc lambda trn cc phin bn c hn, hy nh vo tp {@code
  build.gradle} v t {@code compileSdkVersion} v {@code
  targetSdkVersion} thnh 23 hoc thp hn.
</p>

<h2 id="configuration">
  Kch hot cc tnh nng ca Java 8 v Jack Toolchain
</h2>

<p>
   s dng cc tnh nng mi ca ngn ng Java 8 bn cng cn s dng
  <a class="external-link" href="https://source.android.com/source/jack.html">Jack toolchain</a> mi. Toolchain Android
  mi s bin dch m ngun ca ngn ng Java sang m bytecode
   dex c c ca Android, c nh dng th vin {@code .jack}  ring ca n v cung cp hu ht cc tnh nng
   toolchain di dng mt phn ca cng c ring l: ng gi li, thu gn, lm ri m v
  multidex.
</p>

<p>Sau y l phn so snh hai toolchain c s dng  dng cc tp DEX Android:</p>
<ul>
  <li>Javac toolchain c:<br>
  <b>javac</b> ({@code .java} --&gt; {@code .class}) --&gt; <b>dx</b> ({@code
  .class} --&gt; {@code .dex})
  </li>

  <li>Jack toolchain mi:<br>
  <b>Jack</b> ({@code .java} --&gt; {@code .jack} --&gt; {@code .dex})
  </li>
</ul>

<h3>
  Cu hnh Gradle
</h3>

<p>
   kch hot cc tnh nng ngn ng Java 8 v Jack cho d n ca bn, hy nhp
   ni dung sau vo tp {@code build.gradle} theo m-un:
</p>

<pre>
android {
  ...
  defaultConfig {
    ...
    jackOptions {
      enabled true
    }
  }
  compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
  }
}
</pre>

<h3>
  Vn   bit
</h3>

<p>
  Instant Run, c gii thiu trong Android Studio 2.0 (Beta), hin khng hot ng
  vi Jack v s b v hiu ha khi s dng toolchain mi.
</p>

<p>Bi v Jack khng to ra cc tp lp trung gian khi bin dch mt
ng dng, cc cng c ph thuc vo nhng tp ny hin thi khng hot ng vi Jack. Mt s
v d v cc cng c ny l:</p>

<ul>
  <li>B d Lint hot ng trn cc tp lp
  </li>

  <li>Cc cng c v th vin i hi cc tp lp ca ng dng (nh JaCoCo
  v Mockito)</li>
</ul>

<p><a href="http://tools.android.com/filing-bugs">Vui lng thng bo li</a> nu bn pht hin cc vn  khc khi s dng Jack.</p>