Activity上有兩個按鈕，切換到其他兩個Activity。

1、先建立兩個Button，一個Textview

2、給兩個Button新增監聽器，實現如下程式碼

public class MainActivity extends AppCompatActivity {
    Button bt1_2, bt1_3;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bt1_2 = (Button) findViewById(R.id.button_t2);
        bt1_3 = (Button) findViewById(R.id.button_t3);
        //建立監聽器
        bt1_2.setOnClickListener(listener);
        bt1_3.setOnClickListener(listener2);
    }

    //實現監聽器1：按鍵1，跳到第2張
    Button.OnClickListener listener = new Button.OnClickListener() {
        public void onClick(View v) {
            Intent intent = new Intent(MainActivity.this, Main2Activity.class);
            startActivity(intent);
            MainActivity.this.finish();
        }
    };
    //實現監聽器2：按鍵2，跳到第3張
    Button.OnClickListener listener2 = new Button.OnClickListener() {
        public void onClick(View v) {
            Intent intent = new Intent(MainActivity.this, Main3Activity.class);
            startActivity(intent);
            MainActivity.this.finish();
        }
    };
}