activity的跳转

1.activity1

public class MainActivity extends Activity {

 /**
  * Activity第1次创建时调用
  */
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  System.out.println("FirstActivity->onCreate");
 }
 
 
 public void enter2(View view){
  Intent intent=new Intent();
  intent.setClass(MainActivity.this, SecondActivity.class);
  startActivity(intent);
 }

 /**
  * 1.在代码中明确调用了finish方法
  * 2.Android系统资源不够用时，会优先销毁第1个不可见的Activity
  */
 @Override
 protected void onDestroy() {
  super.onDestroy();
  System.out.println("FirstActivity->onDestroy");
 }

    /**
     * 当启动另外一个Activity时，就会调用第1个Activity的onPause方法
     */
 @Override
 protected void onPause() {
  super.onPause();
  System.out.println("FirstActivity->onPause");
 }

 

 @Override
 protected void onRestart() {
  super.onRestart();
  System.out.println("FirstActivity->onRestart");
 }

 

 /**
  * Activity获得用户焦点时，即与用户交互时
  */
 @Override
 protected void onResume() {
  super.onResume();
  System.out.println("FirstActivity->onResume");
 }

 

 /**
  * Activity能被看到时
  */
 @Override
 protected void onStart() {
  super.onStart();
  System.out.println("FirstActivity->onStart");
 }

    /**
     * 完全被新的Activity遮挡住时调用
     */
 @Override
 protected void onStop() {
  super.onStop();
  System.out.println("FirstActivity->onStop");
 }

 

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.main, menu);
  return true;
 }

}

 

2.secondActivity

public class SecondActivity extends Activity {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_second);
  System.out.println("SecondActivity->onCreate");

 }
 
 public void enter1(View view){
  Intent intent=new Intent();
  intent.setClass(SecondActivity.this, MainActivity.class);
  startActivity(intent);
 }

 @Override
 protected void onDestroy() {
  super.onDestroy();
  System.out.println("SecondActivity->onDestroy");
 }

 @Override
 protected void onPause() {
  super.onPause();
  System.out.println("SecondActivity->onPause");
 }

 @Override
 protected void onRestart() {
  super.onRestart();
  System.out.println("SecondActivity->onRestart");
 }

 @Override
 protected void onResume() {
  super.onResume();
  System.out.println("SecondActivity->onResume");
 }

 @Override
 protected void onStart() {
  super.onStart();
  System.out.println("SecondActivity->onStart");
 }

 @Override
 protected void onStop() {
  super.onStop();
  System.out.println("SecondActivity->onStop");
 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.second, menu);
  return true;
 }

}

 

3.activity_main.xml

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="120dp"
        android:onClick="enter2"
        android:text="进入Activity2" />

4.activity_second.xml

<Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="159dp"
        android:onClick="enter1"
        android:text="进入Activity1" />