我的作业

我的作业

我的跳转作业

fragment需要两个来进行跳转
第一个：

第二个：

下面是主界面java代码 这些都是看同学的修改的。。 public class MainActivity extends AppCompatActivity implements View.OnClickListener{ private Fragment firstFragment; private Fragment secondFragment; private boolean skip = true; private boolean exit = false;

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

blankFragment = new firstFragment();
FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.add(R.id.main, blankFragment);
transaction.commit();
}

public void onClick(View view) {
switch (view.getId()) {
case R.id.btn_main:
jump();
break;
}
}

private void jump() {
boolean exit = true;

if (skip) {
FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
if (secondFragment == null) {
secondFragment = new SecondFragment();
transaction.replace(R.id.main, secondFragment);
transaction.commit();
skip = false;
} else {
transaction.replace(R.id.main, secondFragment);
transaction.commit();
skip = false;
}
} else {
Toast.makeText(this, "This is second fragment!", Toast.LENGTH_LONG).show();
}
}

public boolean onKeyDown(int keyCode, KeyEvent event) {

if (event.getKeyCode() == KeyEvent.KEYCODE_BACK && exit) {

FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
skip = true;
exit = false;
transaction.replace(R.id.main, blankFragment);
transaction.commit();
return false;
} else {
finish();
}
return super.onKeyDown(keyCode, event);

}
}