开启activity

//常用 
Intent i=new Intent(MainActivity.this,MyActivity.class);
                startActivity(i);

//通过component开启
 Intent i=new Intent();
                ComponentName c=new ComponentName("s.jf3q.myactivity","s.jf3q.myactivity.MyActivity");
                 i.setComponent(c);
                 startActivity(i);

关闭activity

finish();

activity之间传递数据（一个页面跳转另一个页面）

传递

 Intent i=new Intent(MainActivity.this,MyActivity.class);
                Bundle bu=new Bundle();
                bu.putCharSequence("realname",realname);
                //将参数放入bundle，并将bundle放置intent中
                i.putExtras(bu);
                startActivity(i);

接收

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

        //从bundle中获取参数
        Intent i=getIntent();
        Bundle bu=i.getExtras();
        String realname=bu.get("realname").toString();

        TextView tv=findViewById(R.id.sr);
        tv.setText(realname);
 
    }

activity之间传递数据（一个页面上弹出另一个页面）

mian

 

public class MainActivity extends AppCompatActivity {
//获取弹出页面的传过来的参数
    @Override
    protected void onActivityResult(int requestCode, int resultCode,   Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(requestCode==0x11&&resultCode==0x11){
            Bundle bu=data.getExtras();
            int id=bu.getInt("img");
            Toast.makeText(MainActivity.this,id+"",Toast.LENGTH_SHORT).show();
        }
    }


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

        Button uip=findViewById(R.id.upimg);
        uip.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                Intent i=new Intent(MainActivity.this,MyActivity.class);
                //弹出页面
                startActivityForResult(i,0x11);
            }
        });
    }


}

弹出的那个页面

 

public class MyActivity extends AppCompatActivity {
    ImageView im;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);

  

          im=findViewById(R.id.img);
        im.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //获取Intent
                Intent i=getIntent();
                Bundle bu=new Bundle();
                bu.putInt("img",im.getId());

                i.putExtras(bu);
                //把intent返回
                setResult(0x11,i);
                finish();//关闭页面
            }
        });
    }
}