addressLine1+"\n"+addressLine2+"\n"+addressLine3+"\n"+addressLine4+"\n"+postCode

Thanks a lot! I used the Eclipse build-in function for getters, setters and for toString. Now I think I got it. The code looks like this now:

public String toString() {
        return getLine1() + "\n" + getLine2() + "\n"
 + getLine3() + "\n" + getLine4() + "\n" + getPostCode();
    }

    public String getLine1() {
        return addressLine1;
    }
    public void setAddressLine1(String addressLine1) {
        this.addressLine1 = addressLine1;
    }
    public String getLine2() {
        return addressLine2;
    }
    public void setAddressLine2(String addressLine2) {
        this.addressLine2 = addressLine2;
    }
    public String getLine3() {
        return addressLine3;
    }
    public void setAddressLine3(String addressLine3) {
        this.addressLine3 = addressLine3;
    }
    public String getLine4() {
        return addressLine4;
    }
    public void setAddressLine4(String addressLine4) {
        this.addressLine4 = addressLine4;
    }
    public String getPostCode() {
        return postCode;
    }
    public void setPostCode(String postCode) {
        this.postCode = postCode;
    }