如何在android中创建线性布局和中心按钮？

Question

In android how can you insert a linear layout using java, and have three buttons in it in a horizontal layout, and have the buttons centered.

So basically I want a horizontal linear layout with three columns and 1 row, each column has the same width, and to insert an image button that's vertically and horizontally centered in each layout cell.

    LinearLayout layout = new LinearLayout(this);
    layout.setOrientation(LinearLayout.HORIZONTAL);
    LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.WRAP_CONTENT);
    layout.setLayoutParams(params);

Does anyone know how to do this?

Thanks.

Answer 1

You can center all child views in a layout by setting the gravity for the layout to center horizontal like:

LayoutParams layout_params = new LinearLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT, Gravity.CENTER_HORIZONTAL);

followed by addView with newly constructed LayoutParams

Answer 2

You can use weightsum = 3 for linearlayout, and layout_weight = 1 for each button. See the detail code. I hope this will help. Good luck :)

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    LinearLayout layout = new LinearLayout(this);
    layout.setOrientation(LinearLayout.HORIZONTAL);
    LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
            LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
    layout.setLayoutParams(params);

    layout.setWeightSum(3);

    for (int i = 0; i < 3; i++) {
        LinearLayout.LayoutParams btnParams = new LinearLayout.LayoutParams(
                LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        btnParams.weight = 1.0f;

        Button btn = new Button(this);
        btn.setText("Btn");
        btn.setLayoutParams(btnParams);

        layout.addView(btn);
    }

    setContentView(layout);
    }
}

Or this code for better but more complicated ^^

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    LinearLayout mainLayout = new LinearLayout(this);
    mainLayout.setOrientation(LinearLayout.HORIZONTAL);
    LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
            LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
    mainLayout.setLayoutParams(params);

    mainLayout.setWeightSum(3);

    for (int i = 0; i < 3; i++) {
        LinearLayout.LayoutParams btnParams = new LinearLayout.LayoutParams(
                LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);

        Button btn = new Button(this);
        btn.setText("Btn");
        btn.setLayoutParams(btnParams);

        LinearLayout childLayout = new LinearLayout(this);
        LinearLayout.LayoutParams childParam = new LinearLayout.LayoutParams(
                LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        childParam.weight = 1.0f;

        childLayout.setLayoutParams(childParam);
        childLayout.setGravity(Gravity.CENTER);
        childLayout.addView(btn);

        mainLayout.addView(childLayout);
    }

    setContentView(mainLayout);
}
}